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Evolution of the Northern Nicaragua Rise during the Oligocene–Miocene: Drowning by environmental factors
Abstract
Possible causes to explain platform drowning have been hotly debated by carbonate sedimentologists for more than a decade now. In this paper, we present multiple evidence to explain the drowning of a carbonate megabank that covered most of the modern Northern Nicaragua Rise (NNR) during an interval spanning from late Oligocene to early Miocene by the interaction of several environmental factors. The recovery during ODP Leg 165 of late Oligocene to middle Miocene sedimentary sequences in the sub-seafloor of the modern channels and basin, Pedro Channel and Walton Basin, respectively, that dissect the NNR (Site 1000) and south of the rise in the Colombian Basin (Site 999), combined with information from dredged rock samples, allows us to explore in more detail the timing and possible mechanisms responsible for the drowning of the megabank and its relationship to Miocene climate change. The modern system of isolated banks and shelves dissected by a series of intervening seaways and basins on the NNR has evolved from a continuous, shallow-water carbonate “megabank” that extended from the Honduras/Nicaraguan mainland to the modern island of Jamaica. Available information suggests that this megabank broke apart and partially drowned in the late part of the late Oligocene at around 27 Ma and finally foundered during the late early Miocene around 20 Ma, resulting in limited neritic coral growth in the areas where the modern isolated carbonate banks and shelves are occurring today. Available information also suggests that the southern and central parts of Pedro Channel were already a deep-water area before the major episode of platform drowning, and its formation predates the initiation of the Caribbean Current. However, after the partial drowning of the megabank, the channel has become a major pathway for the Caribbean Current. Stratigraphic units identified in deep-water carbonates sampled at ODP Sites 999 and 1000 help to constrain the environmental setting leading to the drowning of the banks. Changes in lithology and mass accumulation rates of both the carbonate and non-carbonate fraction parallel stable isotope shifts and likely indicate regional changes in climate and circulation during the late Oligocene–middle Miocene interval. Carbonate mass accumulation rates (MARs) at Site 999 suggest increased regional productivity during the early Miocene. Terrigenous MARs at both Sites 999 and 1000 show a general increase from the Burdigalian through the Serravallian. The temporal association among episodes of neritic platform deposition, followed by increased productivity as identified by higher carbonate MARs and positive excursion in carbon isotopes, suggests that oceanographic changes such as local upwelling and nutrification have led to the partial drowning of the NNR “megabank”.
... To the south, an open carbonate platform developed in shallow marine to inner neritic conditions with localized patch reef formation favored by the distal location of the deltaic wedge ( Figures 15E, 16E). Mutti et al. (2005) determined that mass carbonate production started to decrease circa 27 Ma in the Nicaragua Rise as a precursor of the global event known as the middlelate Miocene carbonate crash (Mutti et al., 2005). By the late Oligocene, the shoreline orientation remains in a constant north-south orientation and is consistent with the accompanying eastward translation (without rotation) of the Caribbean plate by this time ( Figure 15E). ...
... To the south, an open carbonate platform developed in shallow marine to inner neritic conditions with localized patch reef formation favored by the distal location of the deltaic wedge ( Figures 15E, 16E). Mutti et al. (2005) determined that mass carbonate production started to decrease circa 27 Ma in the Nicaragua Rise as a precursor of the global event known as the middlelate Miocene carbonate crash (Mutti et al., 2005). By the late Oligocene, the shoreline orientation remains in a constant north-south orientation and is consistent with the accompanying eastward translation (without rotation) of the Caribbean plate by this time ( Figure 15E). ...
... During the early Miocene, the continuous shallowwater carbonate shelf of the Nicaragua Rise extended from the Honduras-Nicaraguan mainland to the modern island of Jamaica and disintegrated into isolated banks and shelves dissected by a series of intervening seaways in the northeastern Nicaragua Rise like the Rosalind Channel, Diriangen Channel, and Bawihka Channel (Iturralde-Vinent and MacPhee, 1999; Mutti et al., 2005) (Figure 2). As shown by stage 4 in Figure 7, a major pulse of increased subsidence affects the platform with retreat of the deltaic wedge at the mouth of the proto-Coco river and the initiation of the TST2 ( Figure 14F). ...
Late Cretaceous–to–present-day mixed carbonate–clastic deposition along the Nicaraguan platform, western Caribbean Sea, has evolved from a tectonically controlled, rifted upper Eocene shallow–to–deep-marine carbonate–siliciclastic shelf to an upper
Miocene–to–present-day tectonically stable shallow-marine carbonate platform and passive margin. By integrating subsurface data of 287 two-dimensional seismic lines and 27 wells, we interpret the Cenozoic stratigraphic sequence as 3 cycles of transgression and regression beginning with an upper Eocene rhodolitic–algal carbonate shelf that interfingered with marginal siliciclastic sediments derived from exposed areas of Central
America bordering the margin to the west. During the middle Eocene, a carbonate platform was established with both rimmed reefs and isolated patch reefs. A late Eocene forced regression produced widespread erosion and subaerial exposure across much of the platform and was recorded by a regional unconformity. The Oligocene–upper Miocene sedimentary record includes a southeastward prograding delta of the proto-Coco river, which drained the emergent area of what is now northern Nicaragua.
The late Miocene–to–present-day period marks a period of strong subsidence with the development of small pinnacle reefs. We describe favorable petroleum system elements of the Nicaraguan platform that include (1) Eocene fossiliferous limestone source rocks documented as thermally mature in vintage exploration wells and seen as active gas chimneys emanating from inferred carbonate reservoirs; (2) upper–to–middle Eocene reservoirs in patch and pinnacle reefs, middle Eocene calcareous slumps, and Oligocene fluvial-deltaic facies documented in wells; and (3) regional seal intervals that consist
of both regional unconformities and Eocene–Oligocene intraformational shale.
... It is situated in the western portion of the Caribbean Sea and to the west of the Greater Antilles arc. The island of Jamaica forms the northern extent of the Nicaraguan Rise (Fig. 1), a major NE-SW trending bathymetric and structural feature extending as far as Honduras and Nicaragua to the southwest (Hine et al., 1992;Mutti et al., 2005). The Nicaraguan Rise is the north-eastern submarine continuation of the Chortis Block (James, 2007;Carvajal-Arenas et al., 2015;Sanchez et al., 2016;Bunge et al., 2016) and comprises upper and lower parts, divided by the Pedro Bank Fault Zone (Mutti et al., 2005;James, 2007;Ott et al., 2013). ...
... The island of Jamaica forms the northern extent of the Nicaraguan Rise (Fig. 1), a major NE-SW trending bathymetric and structural feature extending as far as Honduras and Nicaragua to the southwest (Hine et al., 1992;Mutti et al., 2005). The Nicaraguan Rise is the north-eastern submarine continuation of the Chortis Block (James, 2007;Carvajal-Arenas et al., 2015;Sanchez et al., 2016;Bunge et al., 2016) and comprises upper and lower parts, divided by the Pedro Bank Fault Zone (Mutti et al., 2005;James, 2007;Ott et al., 2013). Sanchez et al. (2016) infer that the upper part of the Nicaraguan Rise, which includes western and central Jamaica, is underlain by igneous rocks of island-arc affinity, whereas the lower part has an oceanic plateau (Caribbean Large Igneous Province) origin. ...
... The Nicaraguan Rise is bound to the northwest by the Cayman Trough and to the southeast by the remarkably straight Hess escarpment ( Fig. 1), which separates it from the Colombian Basin (Hine et al., 1992;Mutti et al., 2005;James, 2007;James-Williamson et al., 2014;Carvajal-Arenas et al., 2015;Bunge et al., 2016). The Cayman Ridge runs parallel to the northern margin of the Nicaraguan Rise to the north of the Cayman Trough (James, 2007). ...
The island of Jamaica forms the northern extent of the Nicaraguan Rise, an elongate linear tectonic feature stretching as far as Honduras and Nicaragua to the south. Uplift and subaerial exposure of Jamaica during the Neogene has made the island rare within the Caribbean region, as it is the only area where rocks of the Nicaraguan Rise are exposed on land. Biostratigraphic dating and palaeoenvironmental interpretations using larger benthic foraminifera, supplemented by planktonic foraminifera, nannopalaeontology and palynology of outcrop, well and corehole samples has enabled the creation of a regional relative sea-level curve through identification of several depositional sequences. This study recognises ten unconformity-bounded transgressive-regressive sequences which record a complete cycle of relative sea level rise and fall. Sequences are recognised in the Early to ‘Middle’ Cretaceous (EKTR1), Coniacian-Santonian (STR1), Campanian (CTR1), Maastrichtian (MTR1-2), Paleocene-Early Eocene (PETR1), Eocene (YTR1-3) and Late Eocene-Oligocene (WTR1). These transgressive-regressive cycles represent second to fourth order sequences, although most tie with globally recognised third order sequences. Comparisons of the Jamaican relative sea-level curve with other published global mean sea-level curves show that local tectonics exerts a strong control on the deposition of sedimentary sequences in Jamaica. Large unconformities (duration >1 Ma) are related to significant regional tectonic events, with minor overprint of a global eustatic signal, while smaller unconformities (duration <1 Ma) are produced by global eustatic trends. The relatively low rates of relative sea-level rise calculated from the regional relative sea-level curve indicate that carbonate production rates were able to keep pace with the rate of relative sea-level rise accounting for the thick successions of Maastrichtian carbonates and those of the Yellow and White Limestone Groups. Carbonate platform drowning within the White Limestone Group during the Oligocene to Miocene is attributed to environmental deterioration given the low rates of relative sea-level rise.
... It is situated in the western portion of the Caribbean Sea and to the west of the Greater Antilles arc. The island of Jamaica forms the northern extent of the Nicaraguan Rise (Fig. 1), a major NE-SW trending bathymetric and structural feature extending as far as Honduras and Nicaragua to the southwest (Hine et al., 1992;Mutti et al., 2005). The Nicaraguan Rise is the north-eastern submarine continuation of the Chortis Block (James, 2007;Carvajal-Arenas et al., 2015;Sanchez et al., 2016;Bunge et al., 2016) and comprises upper and lower parts, divided by the Pedro Bank Fault Zone (Mutti et al., 2005;James, 2007;Ott et al., 2013). ...
... The island of Jamaica forms the northern extent of the Nicaraguan Rise (Fig. 1), a major NE-SW trending bathymetric and structural feature extending as far as Honduras and Nicaragua to the southwest (Hine et al., 1992;Mutti et al., 2005). The Nicaraguan Rise is the north-eastern submarine continuation of the Chortis Block (James, 2007;Carvajal-Arenas et al., 2015;Sanchez et al., 2016;Bunge et al., 2016) and comprises upper and lower parts, divided by the Pedro Bank Fault Zone (Mutti et al., 2005;James, 2007;Ott et al., 2013). Sanchez et al. (2016) infer that the upper part of the Nicaraguan Rise, which includes western and central Jamaica, is underlain by igneous rocks of island-arc affinity, whereas the lower part has an oceanic plateau (Caribbean Large Igneous Province) origin. ...
... The Nicaraguan Rise is bound to the northwest by the Cayman Trough and to the southeast by the remarkably straight Hess escarpment ( Fig. 1), which separates it from the Colombian Basin (Hine et al., 1992;Mutti et al., 2005;James, 2007;James-Williamson et al., 2014;Carvajal-Arenas et al., 2015;Bunge et al., 2016). The Cayman Ridge runs parallel to the northern margin of the Nicaraguan Rise to the north of the Cayman Trough (James, 2007). ...
The island of Jamaica forms the northern extent of the Nicaraguan Rise, an elongate linear tectonic feature stretching as far as Honduras and Nicaragua to the south. Uplift and subaerial exposure of Jamaica during the Neogene has made the island rare within the Caribbean region, as it is the only area where rocks of the Nicaraguan Rise are exposed on land. Biostratigraphic dating and palaeoenvironmental interpretations using larger benthic foraminifera, supplemented by planktonic foraminifera, nannopalaeontology and palynology of outcrop, well and corehole samples has enabled the creation of a regional relative sea-level curve through identification of several depositional sequences. This study recognises ten unconformity-bounded transgressive-regressive sequences which record a complete cycle of relative sea level rise and fall. Sequences are recognised in the Early to ‘Middle’ Cretaceous (EKTR1), Coniacian-Santonian (STR1), Campanian (CTR1), Maastrichtian (MTR1-2), Paleocene-Early Eocene (PETR1), Eocene (YTR1-3) and Late Eocene-Oligocene (WTR1). These transgressive-regressive cycles represent second to fourth order sequences, although most tie with globally recognised third order sequences. Comparisons of the Jamaican relative sea-level curve with other published global mean sea-level curves show that local tectonics exerts a strong control on the deposition of sedimentary sequences in Jamaica. Large unconformities (duration >1 Ma) are related to significant regional tectonic events, with minor overprint of a global eustatic signal, while smaller unconformities (duration <1 Ma) are produced by global eustatic trends. The relatively low rates of relative sea-level rise calculated from the regional relative sea-level curve indicate that carbonate production rates were able to keep pace with the rate of relative sea-level rise accounting for the thick successions of Maastrichtian carbonates and those of the Yellow and White Limestone Groups. Carbonate platform drowning within the White Limestone Group during the Oligocene to Miocene is attributed to environmental deterioration given the low rates of relative sea-level rise.
... The concept of drowning unconformities is well established and there are many examples of carbonate platform drowning strata documented in the rock record worldwide (e.g., Schlager 1981Schlager , 1989Hallock and Schlager 1986;Longman et al. 1987;Simone and Carannante 1988;Erlich et al. 1990Erlich et al. , 1993Föllmi et al. 1994;Drzewiecki and Simo 1997;Weissert et al. 1998;Blomeier and Reijmer 1999;Wortmann and Weissert 2000;Wissler et al. 2003;Ruiz-Ortiz et al. 2004;Mutti et al. 2005;Föllmi and Gainon 2008;Sattler et al. 2009;Najarro et al. 2011;Marino and Santantonio 2010;Brandano et al. 2016;Sulli and Interbartolo 2016). Carbonate platforms are defined as flat-topped accumulations of carbonate sediments developed at or very near sea level (Hallock and Schlager 1986). ...
... The cause of platform drowning in the Bird's Head is attributed to a reduction in the rates of carbonate accumulation due to the presence of excess nutrients in the depositional systems that are sensitive to a number of environmental factors that may contribute to drowning. Environmental stresses that may lead to carbonate platform demise and the formation of drowning unconformities include oceanic anoxic events, tectonism and flexural loading, hyper-and hypo-salinity, change in carbon dioxide content of the oceans or atmosphere, change in nutrient supply, death of zooxanthellae, temperature, hydrodynamics, turbidity, light penetration, and evolutionary modification (Schlager 1991;Thorne 1992;Hallock and Schlager 1986;Erlich et al. 1990Erlich et al. , 1993Mutti et al. 2005). In all cases, however, platform drowning occurs because the rate of platform top production and accumulation is exceeded by the rate of relative sea-level rise, either because the rate of relative sea-level rise has increased, or because the rate of carbonate production has decreased. ...
... In all cases, however, platform drowning occurs because the rate of platform top production and accumulation is exceeded by the rate of relative sea-level rise, either because the rate of relative sea-level rise has increased, or because the rate of carbonate production has decreased. The process of carbonate platform drowning presents somewhat of a paradox as rates of carbonate production and accumulation normally exceed rates of long-term sea-level rise and subsidence; glacioeustatic sea-level rises, on the other hand, can exceed carbonate production (Schlager 1981;Hallock and Schlager 1986;Föllmi et al. 1994;Wissler et al. 2003;Ruiz-Ortiz et al. 2004;Mutti et al. 2005;Brandano et al. 2016). Kim et al. (2012) demonstrated that even if the rate of relative-sea level rise is lower than maximum carbonate potential platform drowning can still occur if accumulation rates at the initiation of drowning are lower than the rate of relative sea-level rise. ...
Drowning unconformities and their related strata are important records of key tectonic and environmental
events throughout Earth’s history. In the eastern Bird’s Head region of West Papua, Indonesia, Middle Miocene
strata record a drowning unconformity present over much of western New Guinea, including several offshore
basins. This study records platform carbonate strata overlain by mixed shallow- and deep-water units containing benthic and planktonic foraminiferal assemblages in several outcrop locations across the eastern Bird’s Head region. These heterolithic beds are interpreted as drowning successions that are terminated by a drowning unconformity. We define a succession exposed along the Anggrisi River in the eastern Bird’s Head as a stratotype for carbonate platform drowning in the Bird’s Head, analogous to similar faunal turnovers identified in its offshore basins. Detailed facies analyses, biostratigraphic dating, and paleoenvironmental interpretations using larger benthic and planktonic foraminifera collected from the Anggrisi River succession help to constrain the drowning event recorded onshore as beginning in the Burdigalian and ending in the Serravallian. The cause of platform drowning in the Bird’s Head is attributed to a reduction in the rates of carbonate accumulation
due to the presence of excess nutrients in the depositional environment. Already foundering carbonate platforms due to environmental deterioration were left vulnerable to submergence and eventually succumbed to drowning. Low rates of carbonate production were outpaced by the rate of relative sea-level rise caused by high-amplitude oscillations in global glacio-eustatic sea-level change and/or regional tectonic subsidence. The duration of the drowning event across the entire Bird’s Head region is interpreted to have lasted a duration of approximately 9.5 My, between 18.0 and 8.58 Ma. This has implications when interpreting timings of sedimentary basin fill across western New Guinea and in other basins where carbonate platform drowning is recorded.
... Microbially mediated precipitation dominated carbonate production for more than 3 billion years, forming extensive shallow water carbonate platforms throughout the Archean (Walter 1972;Corfu & Wallace 1986;Allwood et al. 2006;Planavsky et al. 2014;Riding et al. 2014;Satkoski et al. 2015;Nutman et al. 2016;McIntyre & Fralick 2017) and Proterozoic. With the appearance of calcareous metazoans, during the late Ediacarian to early Cambrian (Wood 2018;Wood et al. 2019), carbonate systems became significantly more complex with a wide range of metazoan invertebrate taxa, along with calcareous algae and microbes, contributing to carbonate production and carbonate platform development. ...
... Low light levels, associated with a volcanism-induced reduction in the depth of the photic zone, are documented to have produced an array of adverse effects on a range of benthic organisms. These effects will be discussed in detail later but, briefly, include morphological growth responses (Steneck 1986;Edinger et al. 2000;Mutti et al. 2005;Lokier et al. 2009), switch in feeding mode (Álvaro & Clausen 2007), inhibition of substrate recolonisation (Álvaro & Clausen 2007) and full-scale community transitions (Finger & Lipps 1981). ...
Carbonate sediments have been produced and deposited in areas of active volcanism since, at least, the Paleoarchean. Despite early recognition of a significant relationship between volcanism and marine carbonate systems, research in this field has been largely neglected. With increasing recognition of the accelerating effects and significance of anthropogenically-driven climate change on the ocean-atmosphere system, the time is ripe for studying volcanism-influenced carbonates as a natural analogue for future environmental scenarios. We undertake a detailed assessment of the state-of-the-science in our understanding of these systems. We identify significant bilateral division in approaches, with the geological and biological communities rarely interacting. The study of ancient volcanic-carbonate systems, in particular, appears to have ‘fallen-between-two-stools’ with both the volcanic and sedimentological communities shying away from studying these cross-disciplinary systems. Observations of recent volcanic-carbonate interactions are challenging, long periods of volcanic quiescence are punctuated by brief episodes of activity. Recent developments in robust remotely deployable instrumentation offer an opportunity to safely undertake sustained monitoring of these systems before, during and after eruptions. Informed assessment of the likely responses of carbonate ecosystems to future climatic challenges requires the initiation of an integrated, collaborative, cross-disciplinary approach to studying the complex interactions within these challenging mixed depositional systems.
... Nevertheless, our posterior (estimated) divergence times for Caribbean Amazona are in agreement with the previously proposed hypotheses concerning their diversification and its timing [16,20]. Moreover, the dates are consistent with the geological record of the formation of these islands (discussed above): all the inferred parrot speciation events postdate estimated emergence times for the islands and other key geological events in the region, the appearance of potential migration routes, and ecological opportunities following the closure of the Isthmus of Panama, and submergence of the Nicaraguan rise [91][92][93][95][96][97]. ...
... This time only slightly postdates the low sea level minimum of 4.2 MYA [106,107] which would expose the Nicaraguan rise to the greatest extent [99,100]. It was suggested that the original lineages migrated directly to Jamaica (Supplementary Figure S1B,C) [15,16,20], using the then-emergent remains of the drowning Nicaraguan rise as a stepping-stone path [91,92,97] and only then did founders migrate to Cuba and other islands (Supplementary Figure S1C). ...
Amazon parrots (Amazona spp.) colonized the islands of the Greater Antilles from the Central American mainland, but there has not been a consensus as to how and when this happened. Today, most of the five remaining island species are listed as endangered, threatened, or vulnerable as a consequence of human activity. We sequenced and annotated full mitochondrial genomes of all the extant Amazon parrot species from the Greater Antillean (A. leucocephala (Cuba), A. agilis, A. collaria (both from Jamaica), A. ventralis (Hispaniola), and A. vittata (Puerto Rico)), A. albifrons from mainland Central America, and A. rhodocorytha from the Atlantic Forest in Brazil. The assembled and annotated mitogenome maps provide information on sequence organization, variation, population diversity, and evolutionary history for the Caribbean species including the critically endangered A. vittata. Despite the larger number of available samples from the Puerto Rican Parrot Recovery Program, the sequence diversity of the A. vittata population in Puerto Rico was the lowest among all parrot species analyzed. Our data support the stepping-stone dispersal and speciation hypothesis that has started approximately 3.47 MYA when the ancestral population arrived from mainland Central America and led to diversification across the Greater Antilles, ultimately reaching the island of Puerto Rico 0.67 MYA. The results are presented and discussed in light of the geological history of the Caribbean and in the context of recent parrot evolution, island biogeography, and conservation. This analysis contributes to understating evolutionary history and empowers subsequent assessments of sequence variation and helps design future conservation efforts in the Caribbean.
... The early Miocene was a major epoch in the faunal transition in Caribbean coral species and their capacity for reef-building (Budd et al., 1994;Edinger and Risk, 1994;Budd, 2000;Johnson et al., 2009), in which a loss of coral species diversity of 40% is estimated (Johnson et al., 2008). The transition from prominent and diverse Oligocene reefs to depauperate and poorly developed middle Miocene reefs has been loosely tied to a combination of tectonic events (Hoorn et al., 1995;Iturralde-Vinent and McPhee, 1999;Iturralde-Vinent, 2006), changes in ocean circulation due to the closing or narrowing of gateways (e.g., the emergence of the Isthmus of Panama and Drake passage) (von der Heydt andDijkstra, 2005, 2006;Newkirk and Martin, 2009), variations in sea level (Iturralde-Vinent, 2006) and temperature (Mutti et al., 2005), increased regional productivity (Hoorn et al., 1995;Mutti et al., 2005;von der Heydt andDijkstra, 2005, 2006), and enhanced upwelling events (Edinger and Risk, 1994). Understanding the relative importance of these factors requires a better understanding of coral species distribution through time and across the Caribbean region. ...
... The early Miocene was a major epoch in the faunal transition in Caribbean coral species and their capacity for reef-building (Budd et al., 1994;Edinger and Risk, 1994;Budd, 2000;Johnson et al., 2009), in which a loss of coral species diversity of 40% is estimated (Johnson et al., 2008). The transition from prominent and diverse Oligocene reefs to depauperate and poorly developed middle Miocene reefs has been loosely tied to a combination of tectonic events (Hoorn et al., 1995;Iturralde-Vinent and McPhee, 1999;Iturralde-Vinent, 2006), changes in ocean circulation due to the closing or narrowing of gateways (e.g., the emergence of the Isthmus of Panama and Drake passage) (von der Heydt andDijkstra, 2005, 2006;Newkirk and Martin, 2009), variations in sea level (Iturralde-Vinent, 2006) and temperature (Mutti et al., 2005), increased regional productivity (Hoorn et al., 1995;Mutti et al., 2005;von der Heydt andDijkstra, 2005, 2006), and enhanced upwelling events (Edinger and Risk, 1994). Understanding the relative importance of these factors requires a better understanding of coral species distribution through time and across the Caribbean region. ...
In this contribution we describe and illustrate 14 coral morphospecies collected from the early Miocene Siamaná (Aquitanian–Burdigalian) and Jimol (late Burdigalian) formations of the Cocinetas Basin in La Guajira Peninsula, northern Colombia. Eleven were identified as already established species including seven genera belonging to the families Mussidae, Pocilloporidae, Poritidae, Siderastreidae, and Milleporidae; the other three remain in open nomenclature. Nine of the 11 species identified (81%) are extinct. The remaining two living species, Siderastrea siderea and Millepora alcicornis , are common on modern Caribbean reefs. Their presence in the Siamaná Formation extends their temporal range in the Caribbean region to the early Miocene. Most of the taxa described here were hermatypic and zooxanthellate corals of the order Scleractinia, with the exception of the fire coral Millepora alcicornis , of the order Anthothecata, family Milleporidae. The coral fauna recorded in the Siamaná and Jimol formations is typical of shallow and calm waters of the Oligocene–Miocene transition.
... But these changes occur 114 within drifts which all date back to the Middle Miocene, and it seems that the closure of the 115 Central American Seaway likely only briefly invigorated an already strong current (Paulat et al.,116 2019). 117 Other Caribbean gateway changes occur or are thought to occur in the Middle Miocene, 118 including the opening of ocean gateways in the Antilles, although these were always open to 119 surface flow (e.g., Pindell and Kennan, 2009), and the foundering of the Northern Nicaraguan Rise 120 carbonate "megabank" (e.g., Droxler, 1998;Roth et al., 2000;Mutti et al., 2005). The latter event 121 is proposed by Roth et al. (2000) to be the precipitating event in the inception of the Loop 122 Current, which according to this model was completely blocked by the presence of this large 123 shallow carbonate bank south of the Yucatán Strait. ...
The Loop Current is a key component of the northward transport of warm, salty water and an important influence on Gulf of Mexico hydrography. Understanding how the Loop Current will respond to ongoing anthropogenic warming is critically important, but the history of the Loop Current is poorly known. Here, we present the results of a high resolution multichannel seismic survey of sediment drifts on the eastern Campeche Bank associated with the Loop Current. We identify three seismic megasequences: Megasequence A is an Early Cretaceous carbonate platform, Megasequence B comprises Cretaceous to early Cenozoic pelagic carbonates with weak/no contourite current flow, and Megasequence C comprises a series of large contourite drifts representing the inception and history of the Loop Current. The base of the contourites is marked by a regionally mappable unconformity eroding underling strata, sometimes incising hundreds of meters. The drifts contain a succession of sequence sets separated from each other by regional unconformities and comprising massive elongated mounded sediment drifts, then plastered drifts, and then back the massive elongated drifts which characterize modern deposition, with active moats forming on the seafloor. A lack of sediment cores in the study area precludes age determination of these drift deposits, with the exception of the youngest (Late Pleistocene). Comparison to legacy seismic lines across Deep Sea Drilling Project Site 95, just outside our study area, implies that the base of Megasequence C is Oligocene, and that the Loop Current developed during the global reorganization of ocean circulation at the Eocene-Oligocene Transition.
... We argue that assuming continuous carbonate production is not valid in a multi-component carbonate system subjected to environmental changes, where coexisting carbonate producers are affected disparately by parameters like salinity, turbidity, oxygenation and temperature (Mutti and Hallock, 2003;Hallock, 2007, 2008). Environmental disturbance can hamper carbonate production, prevent the factory of keeping up with sea-level, and ultimately lead to platform drowning (Hallock and Schlager, 1986;Mutti et al., 2005). Such events typically mark the stratigraphic record with drowning sequences (Erlich et al., 1990), which can seal underlying reservoirs after burial (Kusumastuti et al., 2002;Wilson and Hall, 2010). ...
Forward stratigraphic modelling is a fast-developing modelling approach, used to test conceptual models, and predict stratigraphic architecture and depositional facies from basin to reservoir scales. Published subsurface applications demonstrate its added value by integrating multidisciplinary data as well as geological concepts into its constraints. When applied to carbonate depositional systems, composed of multiple sediment factories, the co-operating and interdependent production mechanisms remain poorly studied. By applying the technique to a well-studied section of the Maldives carbonate platform, a specific model design—adapted to the geological age and setting, and constrained by available data—sheds light on the interaction of its carbonate producers. The results yield a naturalistic depositional facies distribution and offer insight in the changing relationship between biotic communities during the platform evolution. After calibration, the reference model unequivocally links the formerly proposed genetic model to the seismostratigraphic architecture. Furthermore, the results show how environmental changes (seemingly of secondary impact compared to changes in physical accommodation in the stratigraphic record) can induce substantial fluctuations in carbonate production rates of biotic communities, affect the ecological accommodation, and thus impact the platform architecture. Therefore, it is crucial to treat carbonate production rates during periods of environmental change as variables with associated uncertainties in a forward stratigraphic model setup.
... The potential of a tropical shallow-water carbonate factory to infill accommodation has been seen as a function of the interrelation of an increase in the rate of accommodation and carbonate production. The latter traditionally has been linked to controlling factors such as temperature, salinity, nutrients, turbidity and siliciclastic input, all of which were assumed to affect the benthic carbonate or reef growth potential (Kendall & Schlager, 1981;Hallock & Schlager, 1986;Schlager, 1991;Jenkyns & Wilson, 1999;Mutti et al., 2005). ...
Mesophotic reefs, hardgrounds and current‐controlled pelagic to hemipelagic carbonates are facies marking carbonate platform drowning successions, irrespective of the factors controlling this evolution. A modern analogue of a carbonate platform in a state of drowning, where these facies occur has not been properly reported on to date. In the present study, the sedimentary environments of the Saya de Malha Bank are characterized using a multidisciplinary approach including sedimentology, hydroacoustics, seismics and oceanography. The Saya de Malha Bank edifice with a surface of 40,808 km2 is located in the tropical Indian Ocean and lies in a water depth of 8 to 300 m extending from the surrounding more than 2000 m deep ocean floor, with no reef reaching the sea surface. Mesophotic coral and red algal facies co‐exist with hemipelagic and bioclastic sands, together with a hardground. Ocean currents and internal waves are identified as major sedimentological controlling factors in absence of elevated nutrient influx. Many features distributed along the present‐day Saya de Malha Bank were described from studies presenting fossil examples of carbonate platform drowning. The results herein can therefore be applied to other drowning examples, in cases allowing for more accurate interpretation of the stratigraphic record.
... The two mechanisms that may induce carbonate platform drowning are the intensification of ocean currents (Isern et al. 2005) and nutrient injection which diminishes the importance of carbonate-secreting organisms as platform constructors (Hallock and Schlager, 1986). Seismic imaging of drowned carbonate platforms shows characteristic features such as backstepping of platform-margin facies and late-stage buildups, terminating with strong reflectors along hardgrounds of the drowning unconformity (Mutti et al. 2005;Shahzad et al. 2018). Two features suggest a process of gradual drowning of the MICP over about 3 Ma: ...
The < 900-m-thick Paleogene carbonates of the Maltese Islands and offshore wells comprise 16 facies grouped into 7 carbon-ate facies associations (TA, TB, TC, TD1, TD2, TE1 and TE2). Previous works misclassified facies as belonging to a carbon-ate ramp, which derailed hydrocarbon exploration. This study confirms that the 200-km-wide, flat-topped, Malta isolated carbonate platform consists of coarse-grained, platform margin sediments surrounding the muddy, shallow marine interior that was tectonically segmented by half graben during foreland extension. Dating by correlation to benthic foraminiferal zones reveals two > 15Ma-long depositional hiatuses that bound the Eocene carbonates. Cyclic sediments are capped by Eocene gypsum beds and Oligocene palaeosolsand were controlled by third-order sea level cycles. About 700m of inner platform sediments accumulated from the Eocene (TA and TB) to the early Chattian (TC) until an abrupt and ubiquitous change to platform margin facies dominated by coralline red algae and subordinate corals (TD1). The succeeding transgres-sive rhodalgal biostrome (TD2) aggraded > 40m and prograded into underfilled half graben, later capped by mobile dunes of large benthic foraminifera (TE1). Deeper water oligophotic to aphotic biota (TE2) draped over the platform by the late Chattian. Increased foreland subsidence and the spread of coarse-grained platform margin sediments signals the beginning of the drowning succession reflecting environmental stress, the decline of coral reef builders, reduced sedimentation rate and increased dispersal rates, culminating in hardgrounds along the drowning surface that terminated carbonate platform sedimentation by the end of the Chattian.
... We argue that assuming continuous carbonate production is not valid in a multi-component carbonate system subjected to environmental changes, where coexisting carbonate producers are affected disparately by parameters like salinity, turbidity, oxygenation and temperature (Mutti and Hallock, 2003;Hallock, 2007, 2008). Environmental disturbance can hamper carbonate production, prevent the factory of keeping up with sea-level, and ultimately lead to platform drowning (Hallock and Schlager, 1986;Mutti et al., 2005). Such events typically mark the stratigraphic record with drowning sequences (Erlich et al., 1990), which can seal underlying reservoirs after burial (Kusumastuti et al., 2002;Wilson and Hall, 2010). ...
... The detachment and eastward migration of Chortís would trigger isostatic adjustment processes translated into regional-scale subsidence of the northern part of the Chortís Block, which lower crust was left behind next to nucleus Mexico (Xolapa Complex). This hypothetical subsidence event may be related to the drowning of the northern part of the Nicaragua Rise at around 27 Ma and finally foundered during the late early Miocene around 20 Ma, according to the recovery of drilled cores during the Ocean Drilling Program (ODP) Leg 165 at sites 999 and 1000 (Fig. 1) and information from dredged rock samples analyzed by Mutti et al. (2005). These authors interpret that the Upper Oligocene drowning of the Nicaragua Rise may be related to regional changes in climate. ...
Three successive strain regimes spanning up to ~16 million years were identified from the field, structural and geochronological analyses in Upper Eocene-Oligocene migmatites of the Xolapa Complex around the Puerto Escondido longitude (~97°W), in southern Mexico. A west-facing asymmetric folding affecting diatexites at ca. 38–31 Ma defines Regime A. Regimes B and C affected younger metatexites. Regime B recorded an outward extension at ca. 31–25 Ma, whereas Regime C occurred at ca. 25–22 Ma as NE-directed thrusting. By coupling the Upper Cretaceous-Oligocene tectonic framework of southern Mexico with the dynamics and timing of the identified strain regimes, we interpret that Regimes A to C recorded distinct stages of the separation and eastward migration of the Chortís Block, viewed as a continuous geodynamic episode. According to our proposal, the upper and lower crust of Chortís adjacent to nuclear Mexico were vertically decoupled before its separation by the presence of pre-Eocene crustal anisotropies. Regime A occurred when the Chortís Block rode over the Xolapa Complex during its initial eastward escape. Since this episode, the Chortís Block (upper crust) was captured by the Caribbean plate, whereas the Xolapa Complex (lower crust) remained as the southernmost North America plate. Chortís eastward migration and the consequent unloading of its decoupled lower crust triggered anatexis, isostatic adjustments, and diachronous uplift of the Xolapa Complex (Regime B). The progressive substitution of Chortís by its thinner lower crust in the tectonic configuration next to nuclear Mexico gradually enhanced the local convergence rate between the Farallon/Cocos plate and just-severed North America. The Farallon/Cocos plate was accreted to North America (Regime C) after a critical lengthening of the uprising lower crust along the southern Mexican margin. The local increase of the convergence rate promoted the landward consumption of the Xolapa Complex by subduction erosion since 22 Ma.
... Seasonal fluctuations in both temperature and precipitation also influence the marine currents, clastic nutrient input, and freshwater discharges into the marine basins (Lockwood, 1974). Although the warm ocean temperature in tropical areas is the main mechanism promoting carbonate production, additional factors such as chemical saturation, salinity, turbidity, nutrient availability, and tectonic activity not only control such production on short time scales but also influence the type of carbonate factories (Budd, 2000;Frost, 1977;Johnson et al., 2008Johnson et al., , 2009Klaus et al., 2011;Mutti et al., 2005;Renema et al., 2016;Wilson, 2002Wilson, , 2008Wilson, , 2012Wilson, , 2015. ...
In this chapter, we report existing and new lithostratigraphic information and Sr-isotope chemostratigraphic ages of several Cenozoic marine carbonate successions deposited within numerous Colombian basins. This information is used to link main changes in the shallow marine carbonate factory to regional environ-mental/tectonic events in the tropical SE Circum-Caribbean. Our results and the available literature show that during the Eocene-early Oligocene transition, car-bonate successions developed along the Alta
... However, an interesting possibility for the demise of carbonate buildups that cannot be overlooked is that a sudden abnormal surge in nutrient levels and increased productivity resulting in higher carbonate mass accumulation rates can lead to the drowning of megabanks as observed in the Northern Nicaragua Rise (e.g. 53 ). While it is recognized that several factors including, but not limited to, intensity of chemical weathering, changes in large-scale thermohaline circulation patterns, closure of important seaways and increased continentalization can combinedly contribute to carbonate deterioration, our work provides convincing evidences for confirming, i) the evolutionary mechanism of carbonates under differential tectonics in the southern South China Sea; ii) the adaptability of biogenic ecosystems to resiliently establish themselves on unfavourable substratum under adverse eustatic fluctuations, high turbidity and constant clastic influx in this region; and iii) one of the crucial, if not the most crucial, factors governing the demise of carbonate platforms in southern South China Sea through the indispensable domination of monsoonal wind-driven oceanic currents that is regulated by planetary climatic circulation. ...
During the Miocene, extensive carbonate deposition thrived over wide latitudinal ranges in Southeast Asia despite perturbations of the global climate and thermohaline circulation that affected the Asian continent. Nevertheless, the mechanisms of its emergence, adaptability in siliciclastic-dominated margins and demise, especially in southern South China Sea (SCS), are largely speculative and remains enigmatic along with a scarcity of constraints on paleoclimatic and palaeoceanographic conditions. Here we show, through newly acquired high-resolution geophysical data and accurate stratigraphic records based on strontium isotopic dating, the evolution of these platforms from ~15.5–9.5 Ma is initially tied to tectonics and eustasy, and ultimately, after ~9.5 Ma, to changes in the global climate patterns and consequent palaeoceanographic conditions. Our results demonstrate at least two paleodeltas that provided favourable substratum of elevated sand bars, which conditioning the emergence of the buildups that inadvertently mirrored the underlying strata. We show unprecedented evidences for ocean current fluctuations linked to the intensification of the Asian summer monsoon winds resulting in the formation of drifts and moats, which extirpated the platforms through sediment removal and starvation. This work highlights the imperative role of palaeoceanography in creating favourable niches for reefal development that can be applicable to carbonate platforms elsewhere.
... The convergence of the Caribbean and Florida Strait ε Nd records between 9.5 and 8 Ma documents the full hydrographic reconnection of the two intermediate-depth Sites (Fig. 2). ODP Site 1000 is located in the Pedro Channel, which crosses the Northern Nicaraguan Rise 40 . According to tectonic reconstructions 41 , the Nicaraguan Rise was fully accessible for northward flow only after 9 Ma, which likely explains the convergence of all seawater ε Nd records between 9.5 and 8 Ma. ...
Export of warm and salty waters from the Caribbean to the North Atlantic is an essential component of the Atlantic Meridional Overturning Circulation (AMOC). However, there was also an active AMOC during the Miocene, despite evidence for an open Central American Seaway (CAS) that would have allowed low-salinity Pacific waters to enter the Caribbean. To address this apparent contradiction and to constrain the timing of CAS closure we present the first continuous Nd isotope record of intermediate waters in the Florida Strait over the past 12.5 million years. Our results indicate that there was no direct intermediate water mass export from the Caribbean to the Florida Strait between 11.5 and 9.5 Ma, at the same time as a strengthened AMOC. After 9 Ma a strong AMOC was maintained due to a major step in CAS closure and the consequent cessation of low-salinity Pacific waters entering the Caribbean.
... For example, the Caribbean Current is a warm surface current that flows across the Nicaraguan Rise, into the Yucatan Basin and from there into the Yucatan Channel and across part of the Yucatan Shelf into the Gulf of Mexico where it becomes the Loop Current that swings into the Straits of Florida, becoming the Florida Current and finally is part of the Gulf Stream. In its path, the current's underside is a bottom current across the Northern Nicaraguan Rise, the Campeche Bank, part of the Florida Shelf and the Pourtal es Terrace producing current-related Duan et al. (1993) erosion, non-deposition and drift sedimentation (Mullins et al., 1988;Mutti et al., 2005;H€ ubscher et al., 2010;Hebbeln et al., 2016). In the narrow seaway of the Straits of Florida the current flows across terraces on top of drowned portions of the Florida Platform and delivers sediment to the adjacent drifts (Gomberg, 1976;Bergman, 2005;Mullins et al., 1980). ...
Carbonate environments inhabit the realm of the surface, intermediate and deep currents of the ocean circulation where they produce and continuously deliver material which is potentially deposited into contourite drifts. In the tropical realm, fine‐grained particles produced in shallow water and transported off‐bank by tidal, wind‐driven, and cascading density currents are a major source for transport and deposition by currents. Sediment production is especially high during interglacial times when sea level is high and is greatly reduced during glacial times of sea‐level lowstands. Reduced sedimentation on carbonate contourite drifts leads to early marine cementation and hardened surfaces, which are often reworked when current strength increases. As a result, reworked lithoclasts are a common component in carbonate drifts. In areas of temperate and cool water carbonates, currents are able to flow across carbonate producing areas and incorporate sediment directly to the current. The entrained skeletal carbonate particles have variable bulk density and shapes that lower the prediction of transport rates in energy‐based transport models, which makes a prediction of current velocity based on grain size difficult in carbonates. All types of contourite drifts known in clastic environments are found in carbonate environments but three additional drift types occur in carbonates because of local sources and current flow diversion in the complicated topography inherent to carbonate systems. The periplatform drift is a carbonate‐specific plastered drift that is nearly exclusively made of periplatform ooze. Its geometry is built by the interaction of along‐slope currents and downslope currents, which deliver sediment from the adjacent shallow‐water carbonate realm to the contour current via a line source. Because the periplatform drift is plastered on the slopes of the platforms it is also subject to mass gravity flow and large slope failures. At platform edges, a special type of patch drift develops. These hemiconal platform‐edge drifts also contain exclusively periplatform ooze but their geometry is controlled by the current around the corner of the platform. At the north‐western end of Little and Great Bahama Bank are platform‐edge drifts that are over 100 km long and up to 600 m thick. A special type of channel‐related drift forms when passages between carbonate buildups or channels within a platform open into deeper water. A current flowing in these channels will entrain material shed from the sediment producing areas. At the channel mouth, the sediment‐charged current deposits its sediment load as into the deeper basin. With continuous flow, a submarine delta is built that progrades into the deep water. The strongly focused current forming the drift delta, is able to rework coarse skeletal grains and clasts, making this type of carbonate drift the coarsest drift type. This article is protected by copyright. All rights reserved.
... The onset of drift sedimentation at ca 12Á3 Ma, deduced from the first appearance of a moat channel at the northern conjunction to the Florida Straits and sheeted drifts in the central SC (Fig. 8A), that corresponds with the initiation and/or intensification of the Loop Current flow about 12 to 15 Ma (Mullins et al., 1988) was probably forced by multiple triggers including: (i) the late Middle Miocene climate transition; (ii) the opening of ocean gateways in the Antilles (Pindell & Kennan, 2009); (iii) the foundering of the Northern Nicaragua Rise megabank (Mutti et al., 2005); and (iv) the beginning closure of the Central American Seaway (CAS) (Fig. 10; Coates & Stallard, 2013). Another important factor that influenced the Loop Current flow was the stabilization of the East Antarctic Ice Sheet (Verducci et al., 2007), which facilitated the modern Antarctic Circumpolar Current (ACC; Livermore et al., 2007) and a modern Atlantic Ocean current system. ...
The Santaren Drift between the Great Bahama Bank and Cay Sal Bank (Bahamas) is closely linked to the development of the Gulf Stream and its shape and geometry record the local to global oceanographic, climatic and tectonic events since the Miocene. High‐resolution multichannel seismic data from the Santaren Channel allows detailed insight into the growth phases of the contourite drift and by using the stratigraphic information from Ocean Drilling Program Site 1006 to infer its sedimentation rates. The results bring new understanding to this region and to interpretation of carbonate drifts. The data document that the signatures of a bottom current flow in the Santaren Channel initiated about 12.3 Ma, as indicated by the first occurrence of sheeted drifts and moat development at the northern part of the Santaren Channel. Narrowing and steepening of moat flanks as well as the pronounced upslope migration of the moat reflects a sustained current acceleration of the bottom currents until 5.5 Ma, associated to a transformation into mounded elongated drifts. Between 5.5 Ma and 3.1 Ma, bottom current intensity reached its maximum probably caused by the final closure of the Central American Seaway. The last 3.1 Myr were characterized by a marked increase in volume through flow reaching a maximum during the past 900 ka. Drift growth was driven by the combined sources of export from the shallow‐water carbonate factory and by pelagic rain. The Middle Miocene channel‐related sheeted drift of the inner Santaren Channel is characterized by low accumulation rates, but a rapid increase of accumulation rates occurred during the Early Pliocene. The contourite drift buildup was disturbed by minor erosional phases with narrow moats in the Late Pliocene due to increasing bottom‐current velocities forced by strengthened Atlantic Ocean ventilation. The Early Pleistocene was dominated by increased periplatform sedimentation and margin progradation facilitated by a reduction in along‐slope current flow speed and a concurrent widening and flattening of the moats. This article is protected by copyright. All rights reserved.
... A switch from Burdigalian carbonate dominated system to siliciclastic dominated succession in the Late Burdigalian-Serravallian surrounding the Mediterranean region ( John et al., 2003 referred to the maps in Esteban, 1996). In addition, the carbonate platform in the North Nicaraguan Rise as part of the Tethys Ocean recorded a general increase in the siliciclastic influx from the Burdigalian through the Serravallian ( Mutti et al., 2005). ...
Four measured sections (each 25-75 m thick) of the Miocene Ar-Rajmah Group carbonate rocks in Cyrenaica, northeast Libya, were sampled every 0.5 m for whole rock stable isotope (δ 18 O, δ 13 C) chemostratigraphy. The Ar-Rajmah Group chemostratigraphic data indicates this unit preserves a record of almost the entire Miocene. The Early Miocene stable isotope record is generally enriched in both δ 18 O and δ 13 C, the Middle Miocene is enriched in δ 13 C but depleted in δ 18 O, and the Late Miocene is depleted in both δ 18 O and δ 13 C. The δ 18 O data ranges from-9.2 to 3.7 ‰ VPDB, and the δ 13 C data ranges from-6.7 to 3.0 ‰ VPDB. The shallowing upward Cyrenaican Miocene carbonate rocks are made up of two shallowing upward 2 nd-order supersequences (SS1-SS2) that contain six 3 rd-order sequences (S1-S6). Four important chemostratigraphic events are recorded in the 3 rd-order sequences in the Cyrenaican Miocene. The Cyrenaican Middle Miocene 3 rd-order sequence 3, Langhian-Serravallian, has the highest enrichment of both oxygen and carbon isotopes, which coincides with the Monterey carbon maximum event, a high gamma ray zone of the maximum flooding zone, and siliciclastic influx. The increased δ 13 C upward enrichment in 3 rd-order sequence 3 was produced by increased carbonate productivity and river runoff. The Tortonian 3 rd order sequence 4 has the 2 The whole world deserve to see this excellent work. This is my full paper manuscript, I have no time, no money, and no nerves to publish it. It has been kept "frozen" in the office drawers for three years for "editing". This work is complete just needs the expert and honest eye to do text editing and formatting, If you have time and money and you are non-racist and non-discriminatory respectful Journal, contact me to get the permission to publish it. most depleted δ 13 C and δ 18 O records and both are depleted progressively up section due to the emergence of the progressively shallowing restricted shallow-water carbonate platform.
... (2) Pinnacle reefs are present on this line and are localized on rift-related structural highs that by the early-middle Miocene failed to keep up with sea-level rise (Mutti et al., 2005) and were subject to regional drowning (Cunningham, 1998) (Figure 9). (3) The upper Miocene regional unconformities are identified along the upper and lower Nicaraguan Rise ( Figure 9). ...
The San Andres rift (SAR), located on the lower Nicaraguan Rise, is a previously poorly studied, active, 015°-trending, bathymetric, and structural rift basin that is 11–27 km (7–17 mi) wide and extends for 346 km (215 mi) across the western flank of the Caribbean plate. In this study, we integrate bathymetric maps, potential field data, and high-resolution, two-dimensional (2-D) seismic lines to understand the crustal structure, tectonic history, and tectonic origin of the SAR, which is one of the active areas within the otherwise stable Caribbean plate. We compiled regional gravity and magnetic data that revealed a negative gravity anomaly and positive magnetic anomaly that we interpret as a result of crustal thinning and an elevated Moho along the main rift axis of the SAR. Forward models of gravity data show four possible interpretations for the origin of the crust underlying and surrounding the SAR. Interpretations of 2-D seismic reflection data show structural features within the upper crust and sedimentary sections typical of other active rift systems including a SAR-parallel, north–south alignment of earthquakes with the larger events showing normal and strike-slip focal mechanisms. Sequential kinematic restorations based on 2-D seismic profiles reveal three major phases of SAR opening: (1) the initial early Eocene rifting stage; (2) middle Eocene extension; and (3) a rapid middle Miocene to early Pliocene extension accompanied by emergence of the San Andres Island as a rift shoulder. We propose slab rollback and intraplate extension as main tectonic mechanisms to explain all rift phases and Neogene volcanism found in the western Caribbean region.
... Several recently published papers have demonstrated that shallowwater carbonates can preserve the original carbon isotope signature (John et al., 2003;Mutti et al., 2005;Franceschi et al., 2014;Brandano et al., 2015;Frijia et al., 2015), and show higher amplitude carbon isotope shifts in comparison to the coeval pelagic successions (Brandano et al., 2017b). Within the shallow-water skeletal associations, the heterozoan carbonates have greater potential to preserve the original marine isotopic ratios compared to the photozoan skeletal assemblages (Mutti et al., 2006) due to their mineralogical composition that is low-Mg calcite-dominated, which makes them more resistant to diagenetic alteration. ...
The Eocene-Oligocene transition marks a fundamental step in the evolution of the modern climate. This climate change and the consequent major oceanic reorganisation affected the global carbon cycle, whose dynamics across this crucial interval are far from being clearly understood. In this work, the upper Eocene to lower Oligocene δ13CCarb and δ13CTOC records of a shallow-water and a hemipelagic carbonate settings within the Central Mediterranean area have been studied and discussed. The shallow-water carbon isotope signal has been analysed in the northern portion of the Apula Platform, cropping out in the Majella Mountain, Central Apennines (Santo Spirito Formation). A coeval Umbria-Marche basinal succession has been investigated in the Massignano section (Conero area, Central Italy). The purposes of this work are: to discriminate between the global and the local (Mediterranean) signature of C-isotope record during the Oi-1 event, to correlate the regional C-isotope signal with the global record, and to evaluate the carbon cycle dynamics across the greenhouse-icehouse transition through the integration of complementary records (shallow-water vs pelagic settings, δ13CCarb vs δ13CTOC). The upper Eocene carbon isotope record of the analysed successions matches with the global signal. The overall trend shows a decrease of the δ13CCarb and a contemporary increase of the δ13CTOC. The decoupling of the two curves is consistent with a reduced fractionation effect by primary producers that characterised the interval between the Middle Eocene Climatic Optimum and the onset of the Oi-1 event. However, regional factors superimposed the global signal. In fact, the upper Eocene basinal δ13CTOC record is marked by short-term negative spikes, which possibly represent times of higher productivity triggered by the westward subtropical Eocene Neotethys current entering from the Arabian-Eurasian gateway. On the contrary, the shallow-water record does not display these short-term productivity pulses. A change in the carbonate factory is only recorded at the Eocene-Oligocene transition, marked by a reduction of the larger benthic foraminifera and the spread of seagrass and corals. Moreover, in the shallow-water record of the Santo Spirito Formation, no major carbon isotope shift related to the Oi-1 event is recorded due to the presence of extensive slumps that disrupt the bedding. These slumps are the main evidence of the sea-level drop that occurred concomitantly with the onset of the Antarctica ice-sheet, which caused the deepening of the storm wave base and increased the instability over the entire ramp.
... The island of Jamaica and the region of the northern Nicaragua Rise are described to have been part of a continuous carbonate 'megabank' during the Paleogene (Droxler et al., 1991;Droxler et al., 1993;Sigurdsson et al., 1997;Mutti et al., 2005). Due to the absence of Paleogene reef-building organisms along the 'megabank' depositional settings are described using carbonate ramp terminology, defined by Burchette and Wright (1992). ...
Jamaica and its offshore basins are sparsely explored: only two wells have been drilled offshore and nine wells onshore, along with several shallow boreholes, and oil or gas shows have been seen in 10 of the 11 wells. Jamaica has a broad stratigraphic framework consisting of Cretaceous shales representing potential source rocks, and rudist limestones with reservoir potential. The Cretaceous succession is overlain by Palaeogene carbonate and siliciclastic units which have both source and reservoir potential. The Middle Eocene Litchfield Formation is recognised as the main Cenozoic source rock, with potential reservoirs in the overlying Chapelton Formation and younger rocks. This data-rich study comprises new analyses of over 800 outcrop and well/borehole samples. New biostratigraphic and sedimentological data have enabled revision and updating of the sequence stratigraphic framework of Jamaica and the tie of depositional cycles to third-order sequences. Biostratigraphic analysis reveals several major unconformities. These are related to major tectonic (predominantly collisional) events that occurred during the assembly of the various terranes of the Nicaragua Rise. The environmental preferences of organisms identified during the biostratigraphic analyses permit the construction of a relative sea-level curve for the island of Jamaica. This curve reveals several newly identified transgressive-regressive (T-R) depositional cycles in the stratigraphy. Maximum transgressive and regressive inflections in the relative sea-level curve are associated with third-order sequences. Single T-R cycles are identified within the Early Cretaceous, Coniacian-Santonian and Campanian, two T-R cycles are identified in the Maastrichtian, a further single T-R cycle within the Paleocene to Early Eocene, three T-R cycles within the Middle Eocene age Yellow Limestone Group and a single transgressive sequence within the Late Eocene to Miocene age White Limestone Group. Transgressions and regressions that are recorded within the Yellow Limestone Group represent changes in relative sea-level of only several tens of metres. Application of this new relative sea-level curve has enhanced the identification of potential source, reservoir and seal units within the petroleum systems of Jamaica.
... In this scenario, the locally increased continental derived input from the Alps may have affected the 87 Sr/ 86 Sr isotope signature of seawater. Evidence of increased runoff related to the Mi-1 events lies in enhanced nutrient availability as recorded by basinal successions (Brandano et al., 2015;Föllmi et al., 2008;Mutti et al., 2005). At the time, Mediterranean carbonate platforms experienced a shift from photic to photo-independent skeletal assemblages Brandano et al., 2015;Föllmi et al., 2008;Foresi et al., 2007). ...
The Miocene is a key interval in the geodynamic and oceanographic evolution of the Mediterranean marking the transition from a wide open basin to the modern closed basin. We used the Sr and Nd isotope records of two Miocene carbonate successions in the Adriatic to document that the evolution of the Mediterranean Basin controlled its seawater chemistry. During the late Aquitanian (~21 Ma), a time of glaciation and sea level lowstand, increased runoff affected the Sr isotope ratios of Mediterranean waters, whereas during the Burdigalian (20.44–15.97 Ma) volcanism in the circum-Mediterranean area mainly influenced the Sr isotopic signature. During the Langhian (15.97–13.82 Ma), a time of sea level highstand associated with the Middle Miocene Climatic Optimum, the Nd isotope values indicate that waters exchanged between the Paratethys and the Central Mediterranean. The Central Mediterranean was well connected with the Atlantic Ocean between the Langhian and the early Tortonian (15.97–11.5 Ma), but exchange of water with the Paratethys declined. In the Messinian (6.3 Ma), connections between some marginal Mediterranean basins, for example, the proto-Adriatic basin, and the Central Mediterranean, became restricted. In this basin, the Sr isotope values fell below the global reference line, while Nd isotope ratios show a strong affinity with the Atlantic Ocean and also indicate freshwater input. We conclude that the Mediterranean Nd isotope signature differs from that in the open oceans and reflects the basin physiography, reflecting a mix of signals derived from the adjacent oceans and local signals.
... The processes and products of carbonate drowning have been analysed from various points of view: from geometry in seismic profiles and/or outcrops (Schlager, 1981(Schlager, , 1989Erlich et al., 1990;Longo and Hyare, 1993;Drzewiecki and Simo, 1997;Ruiz-Ortiz et al., 2004;Mutti et al., 2005;Sulli and Interbartolo, 2016), from paleo-ecology and shifts in carbonate production (Hallock and Schlager, 1986;Simone and Carannante, 1988;F€ ollmi and Gainon, 2008;Sattler et al., 2009) and geochemical data (F€ ollmi et al., 1994;Weissert et al., 1998;Wortmann and Weissert, 2000;Wissler et al., 2003;Najarro et al., 2011), whereas only a few examples concern the frequency distribution of types of grains before and after the drowning event (Blomeier and Reijmer, 1999). Quantitative analysis of allochems can reliably interpret carbonate environments, since the modal composition of carbonate rock reflects the complexity of environmental controls affecting such platforms (Reijmer, 1998;Flügel, 2004;Preto, 2012). ...
This work illustrates the evolution the Lower Jurassic shallow-water carbonates known as the Calcare Massiccio Formation in the Central Apennines (Italy). The Calcare Massiccio is characterized by lateral and vertical variability in the facies associations, related to an articulated physiography of the Triassic to Lower Jurassic carbonate platform and to its tectonic evolution. This work documents the depositional environment changes during the platform evolution. Quantitative analysis on samples collected from three stratigraphic sections were performed through the Calcare Massiccio succession allowed up to the overlying Pliensbachian pelagites. Two type of carbonate sedimentation have been recognized: in the peritidal and shallow subtidal environments (Calcare Massiccio A) the carbonate production is dominated by microbial activity, while the carbonate sedimentation in a deeper environment of middle to outer ramp (Calcare Massiccio B), is dominated by a bioclastic sedimentation.
The evolution from the Calcare Massiccio A to the B can be interpreted as the product of increase of accommodation that in turn produced a backstepping of carbonate facies belt, the photic microbial dominated peritidal facies developed on the persistent Latium-Abruzzi Platform while the bioclastic carbonate production factory settled on the structural highs resulting from the dismembering of the platform by syn-sedimentary tectonic.
The bioclastic carbonate factory was not efficient in filling the available accommodation space produced by Sinemurian extensional tectonic. This inefficiency was amplified by the restricted area available for this factory in the small structural highs. These conditions were sufficient to predispose the platform to the drowning without invoke change in the trophic resource or change in the palaeoceanography
... The result is an asymmetric platform geometry where the upcurrent side is relatively sediment starved and the most sediment is deposited on the downcurrent slope (Fig. 7). This current-controlled offbank transport is also observed on ''incipiently drowned'' platforms, such as the Nicaraguan Rise, where currents sweep across the platform and export sediment to the adjacent slopes (Glaser and Droxler, 1991;Mutti et al, 2005). In contrast, the shallow (0-7 m water depth) tropical carbonate platforms like the modern Great Bahama Bank tend to have very steep slopes (Grammer et al., 1993). ...
... (2) Pinnacle reefs are present on this line and are localized on rift-related structural highs that by the early-middle Miocene failed to keep up with sea-level rise (Mutti et al., 2005) and were subject to regional drowning (Cunningham, 1998) (Figure 9). (3) The upper Miocene regional unconformities are identified along the upper and lower Nicaraguan Rise ( Figure 9). ...
... Relative sea-level rise (eustatic and/or subsidence induced) and the related inability of the reef builders to keep pace are the common drowning mechanisms, especially over glacial-interglacial timescales (Campbell, 1984;Samankassou, 1999;Webster et al., 2004aWebster et al., ,b, 2006Webster et al., , 2009Cabioch et al., 2008). Over longer timescales, other factors such as anoxia, clastic and nutrient input, long-term climatic changes, platform-margin collapse, variations in salinity, and changes in carbonate producers might also play an important role in the drowning process (Hallock and Schlager, 1986;Blomeier and Reijmer, 1999;Mutti et al., 2005;Gawlick and Schlagintweit, 2006;Föllmi and Gainon, 2008). ...
... It is widely documented that, during the Oligocene-Miocene transition, the Mediterranean carbonate platforms were affected by a crisis of carbonate production (Mutti et al., 2005;Foresi et al, 2007;Föllmi et al., 2008;Brandano et al., 2015). This crisis was induced by regional and global factors. ...
The stratigraphic architecture of the Bolognano Formation documents the evolution of the Majella carbonate platform in response to global and local changes that affected the Mediterranean area during the Oligocene–Miocene interval. The Bolognano Formation consists of a homoclinal rampthat developed in a warm, subtropical environment. Five different lithofacies associations have been identified: Lepidocyclina calcarenites, cherty marly limestones,
bryozon calcarenites, hemipelagic marls and marly limestones, and Lithothamnion limestones. Each association corresponds to a single lithostratigraphic unit except for the Lepidocyclina calcarenites that form two distinct lithostratigraphic units (Lepidocyclina calcarenites 1 and 2). These six units reflect alternation of shallow-water carbonate production and drowning. Specifically, two of the three stages of shallow-water carbonate production regard the development of wide dune fieldswithin the middle ramp, one stage dominated by red algae and a seagrass
carbonate factory, whereas the two drowning phases are represented by marly cherty limestones and calcareous marls. A new biostratigraphic framework for Bolognano Formation is presented, based on high resolution analysis of calcareous nannofossil assemblages, which proved to be very useful for biostratigraphic constraints also in shallow-water settings. Using this approach, we have linked the first drowning phase, late
Chattian–Aquitanian p.p. in age, towestern Mediterranean volcanismand the Mi-1 event, and the second drowning phase, late Burdigalian–Serravallian in age, to the closure of the Indo-Pacific passage and the occurrence of the global Monterey event. These results permit a new deciphering, in terms of sequence stratigraphy, of the Bolognano Formation that is interpreted as a 2nd-order super-sequence that can be subdivided into 3 transgressive–regressive sequences.
... The Nicaraguan Rise (NR) is a major crustal feature that is the eastern submarine extension of the Chortis Block and the western extension of the Jamaican Greater Antilles, with a maximum crustal thickness from seismic refraction studies of about 22-28 km (Ewing et al. 1960;Arden 1969;Holcombe et al. 1990) (Fig. 1). Well data and onshore mapping shows that the NR basement consists of Jurassic -Lower Cretaceous lava flows and mafic intrusions, followed by upper Cretaceous clastic and carbonate sedimentation alternating with tuffs and volcaniclastic rocks, and predominantly marine clastic and carbonate deposition during the Cenozoic (Arden 1969;Mutti et al. 2005). Seismic, field, geochemical and petrological studies indicate an island arc affinity in crystalline basement rocks of the NE NR (Arden 1975;Lewis et al. 2011) and an oceanic plateau origin in the SE NR (Mauffret & Leroy 1997;Sinton et al. 2000). ...
Northern Honduras and its offshore area include an active transtensional margin separating the Caribbean and North American plates. We use deep-penetration seismic-reflection lines combined with gravity and magnetic data to describe two distinct structural domains in the Honduran offshore area: (1) an approximately 120 km-wide Honduran Borderlands (HB) adjacent to the Cayman Trough characterized by narrow rift basins controlled by basement-involving normal faults subparallel to the margin; and (2) the Nicaraguan Rise (NR), characterized by small-displacement normal faulting and sag-type basins influenced by Paleocene–Eocene shelf sedimentation beneath an Oligocene–Recent, approximately 1–2 km-thick carbonate platform. Thinning of continental crust from 25–30 km beneath the NR to 6–8 km beneath the oceanic Cayman Trough is attributed to an Oligocene–Recent phase of transtension. Five tectonostratigraphic phases established in the HB and NR include: (1) a Late Cretaceous uplift in the north and south-dipping thrusting related to the collision in the south, between the Chortis continental block and arc and oceanic plateau rocks of the Caribbean; (2) Eocene sag basins in the NR and minor extension in the HB; two phases (3) and (4) of accelerated extension (transtension) across the subsidence mainly of the HB; and (5) Pliocene–Recent minor fault activity in the HB and a stable carbonate platform in the NR.
... The proposed Oligocene glaciation would have been significantly warmer than that of today. Mutti et al. (2005) . 2). ...
... Relative sea-level rise (eustatic and/or subsidence induced) and the related inability of the reef builders to keep pace are the common drowning mechanisms, especially over glacial-interglacial timescales (Campbell, 1984;Samankassou, 1999;Webster et al., 2004aWebster et al., ,b, 2006Webster et al., , 2009Cabioch et al., 2008). Over longer timescales, other factors such as anoxia, clastic and nutrient input, long-term climatic changes, platform-margin collapse, variations in salinity, and changes in carbonate producers might also play an important role in the drowning process (Hallock and Schlager, 1986;Blomeier and Reijmer, 1999;Mutti et al., 2005;Gawlick and Schlagintweit, 2006;Föllmi and Gainon, 2008). ...
... Several recently published papers have demonstrated that shallowwater carbonates can preserve the original carbon isotope signature (John et al., 2003;Mutti et al., 2005;Franceschi et al., 2014;Brandano et al., 2015;Frijia et al., 2015), and show higher amplitude carbon isotope shifts in comparison to the coeval pelagic successions (Brandano et al., 2017b). Within the shallow-water skeletal associations, the heterozoan carbonates have greater potential to preserve the original marine isotopic ratios compared to the photozoan skeletal assemblages (Mutti et al., 2006) due to their mineralogical composition that is low-Mg calcite-dominated, which makes them more resistant to diagenetic alteration. ...
This work focuses on the Bartonian to lower Rupelian interval of the Santo Spirito Formation (Danian-Rupelian) outcropping in the northern sector of the Majella Mountain (Central Apennines).
In this sector the investigated deposits represent the sedimentation in middle to outer ramp environments. The outer ramp consists of marly, highly bioturbated wackestone to packstone with planktonic foraminifers deposited within the aphotic zone and below the storm-weather wave base. The transition between middle and outer ramp is represented by cross-bedded bioclastic packstones that formed three-dimensional submarine dunes migrating basinward. The main components are echinoid fragments, encrusting foraminifers such as Gypsina, usually hooked, acervuliniids, Planorbulina, Lobatula lobatula, both articulated and encrusting red algae fragments and rotaliids. Minor components are bryozoan fragments, deep water small benthic foraminifers such as buliminaceans and frequent planktonic foraminifers. These skeletal assemblages suggest the presence of a carbonate factory associated with a vegetated environment. The middle ramp was characterized by a third lithofacies consisting in a larger benthic foraminifera floatstone. The main components are Nummulites, Discocyclina, Assilina, Asterocyclina, alveolinids tests, together with abundant Gypsina, rotaliids and coral fragments. This facies is interpreted to represent the sediment filling rip channels, placed perpendicular to coastline, and formed during storm events.
The stratigraphic architecture of the S. Spirito Fm in the investigated area has been interpreted as a depositional sequence of high rank that can, in turn, be subdivided into 7 low rank depositional sequences, each of which shows preserved deposits attributed to TST and HST.
... It is widely documented that, during the Oligocene-Miocene transition, the Mediterranean carbonate platforms were affected by a crisis of carbonate production (Mutti et al., 2005;Foresi et al, 2007;Föllmi et al., 2008;Brandano et al., 2015). This crisis was induced by regional and global factors. ...
... The two mechanisms that may induce carbonate platform drowning are the intensification of ocean currents (Isern et al. 2005) and nutrient injection which diminishes the importance of carbonatesecreting organisms as platform constructors (Hallock and Schlager 1986). Seismic imaging of drowned carbonate platforms shows characteristic features such as backstepping of platform-margin facies and late-stage buildups, terminating with strong reflectors along hardgrounds of the drowning unconformity (Mutti et al. 2005;Shahzad et al. 2018). Two features suggest a process of gradual drowning of the MICP over about 3 Ma: ...
The break-up of Pangaea and the Late Mesozoic global sea-level rise drowned many Tethyan carbonate platforms although the resilient Malta Platform aggraded >4 km of carbonates along the North African passive margin where it was isolated from continental siliciclastics. Carbonate sedimentation was terminated by extensive Late Cretaceous to Early Paleogene depositional hiatuses, but renewed during the OChattian reflects Antarctic deglaciation that increased both precipitation over North Africa and nutrient flux in the Tethys, favouring heterozoan ecosystems.
The mid-Chattian transgressive heterozoan carbonates draped over structured bathymetry of an antecedent extensional regime that produced rotated fault-blocks. Highstand shedding of coralline red algae resulted in large clinoforms prograding into partly filled NNE trending half-graben (<10 km-wide) in the Maltese Islands whereas block rotation involving deep, en echelon listric faults formed escarpments along the platform margin. The escarpments were initially onlapped by syntectonic early Palaeogene sediments and later downlapped by prograding complexes. The central platform zone developed as a >50 km-wide basin by lithospheric sagging over a failed Mesozoic rift.
The late Chattian climatic optimum was reflected by a further decrease in the oxygen isotope ratio and aridity over North Africa and favoured a return to the photozoan association during the last phase of the Oligocene sedimentary triplet. Lepidocyclinids flourished in inner to mid-platform environments forming banks although the rate of accumulation of these hydrodynamic foraminifera did not keep up with sea-level rise. The shift to increased trophic resources by the end Oligocene terminated shallow marine carbonate sedimentation which resulted in the drowning of the Malta Platform.igocene, when basinward carbonate progradation began to drape over the >350 km long, cusp-shaped escarpment along the eastern margin of the isolated platform.
This study sub-divides the Oligocene sediments of Malta into eight facies associations. The facies consist of carbonate grains of coral, coralline red algae and large benthic foraminifera which dominated sediments of the Late Rupelian to early Chattian, mid-Chattian and late Chattian, respectively. These successive carbonate factories produced the photozoan-heterozoan-photozoan triplet of carbonate grain associations which, when dated by benthic foraminiferal biozonation, correlates to the succession of carbonate grain associations in other Mediterranean carbonate platforms.
The sedimentary triplet reflects abrupt changes in carbonate ecosystems that coincide with the last three of six surfaces that extend >80 km around Malta. The surfaces show evidence of the influence of meteoric water and pedogenic processes recognised by diagenetic features and isotopic excursions. These sequence boundaries sub-divide the succession into seven depositional sequences that reflect global third-order cyclic sea-level falls produced by glaciations with a periodicity of 1.2 Ma triggered by low-amplitude obliquity variations of the Earth’s axis combined with orbital eccentricity cycles.
The periodic growth of the Antarctic ice-sheet during the Oligocene also affected Tethyan climate by shifting low latitude climate belts northwards. It is suggested that increased aridity over North Africa had reduced nutrient flux to the Tethys and favoured photozoan carbonate biota over the Malta Platform and other Tethyan carbonate platforms. The stepwise decrease in oxygen isotope ratio by the mid-
... Jamaica is the uplifted, northernmost extent of the northern Nicaragua Rise (Fig. 1A). The Nicaragua Rise is a Cretaceous submarine volcanic plateau overlain with 5–7 km of Tertiary carbonates (Arden, 1975; Duncan et al., 1999; Mutti et al., 2005). The Nicaragua Rise extends for over 700 km NE-SW from Nicaragua to Jamaica (Lewis and Draper, 1990; Robinson, 1994). ...
Jamaica is located on a restraining bend on the E-trending, left-lateral plate boundary between the Gonave microplate and Caribbean plate. Deformation in southern Jamaica occurs on two reactivated and simultaneously active fault sets: NNW-striking reverse faults and E-striking strike-slip faults. Movement on NNW-striking reverse faults forms fault-propagation folds that are expressed topographically as the Don Figuerero, Santa Cruz, and Brisco Mountains. The NNW-trending ranges (and faults) of southern Jamaica terminate against the E-W-oriented strike-slip faults. The two dominant E-striking, left-lateral strike-slip faults are the South Coast fault zone in the south and the central Jamaica fault system (Cavaliers fault, Rio Minho-Crawle River fault, and the Siloah fault system) in the central part of the island. We propose that the restraining bend is the result of reactivated, interacting fault arrays in southern Jamaica. The two fault systems inherited from Cretaceous and Paleogene deformation are reactivated to accommodate current deformation. The NNW-striking reverse faults accommodate E-W shortening, and the E-striking strike-slip faults accommodate both the plate motion and the differential motion of the fault blocks bounded by the NNW-striking reverse faults. This geometry results in topographic highs and lows along strike of the strike-slip faults, as a result of vertical displacement on the NNW-striking reverse faults.
... The geometry and facies of drowned carbonate platforms mime a rise of the sealevel even during periods of sea-level stability. In the specific case of carbonate platform drowning, the special behavior of carbonate systems has been often related to a change in the ecology or biology of carbonate producers, in turn commonly linked to climate and/or environmental changes (Schlager, 1981(Schlager, , 2003Hallock and Schlager, 1986;Jenkyns, 1991;Mutti et al., 1997Mutti et al., , 2005Weissert et al., 1998;Wilson et al., 1998;Mutti and Hallock, 2003;Pomar et al., 2004;Föllmi and Godet, 2013;Godet et al., 2013;among others). In the Triassic of the Dolomites (northeastern Italy, Fig. 1A), sedimentary sequences are dominated by carbonates. ...
Sedimentary facies analysis aided by quantitative 3D georeferenced field data are applied to constrain the sequence stratigraphy of a complex stratigraphic interval in the Late Triassic of the Dolomites. This multidisciplinary approach was the key to disentangle the timing of climatic change vs. sea-level fluctuation and their effects on shallow water carbonate depositional systems. The “Carnian Pluvial Event”, a global episode of climate change worldwide documented at low latitudes, involved increased rainfall and possibly global warming. This climatic event begins before a drop of sea-level and caused the demise of microbial-dominated high-relief carbonate platforms that dominated the Dolomites region, and was followed by a period of coexistence of small microbial carbonate mounds and arenaceous skeletal-oolitic grainstones. A subsequent sealevel fall brought to the definitive disappearance of microbialites and shallow water carbonates switched to ramps dominated by oolitic-bioclastic grainstones. The crisis of early Carnian shallow water carbonate systems of the Dolomites generated a geological surface similar to a drowning unconformity, although no transgression occurred. As the high-relief microbial carbonate systems characterized by steep slopes switched to gently inclined oolitic-skeletal-siliciclastic ramps, basins were rapidly filled. The change of carbonate depositional systems was associated with an increase in siliciclastic input, in turn triggered by the onset of a humid climatic event and only later to a sealevel drop. This evolution of carbonate systems cannot be interpreted in the light of sea-level changes only: climate change, and consequent ecological changes in the main carbonate producing biotas, induced significant modifications in depositional geometries. This case study may serve as a conceptual model for the sedimentary evolution of carbonate systems subject to ecological crisis that do not evolve in platform drowning because, despite a drop in shallow water carbonate production, a combination of low subsidence and/or sea level drop maintains the platform top at shallow depth.
... The geometry and facies of drowned carbonate platforms mime a rise of the sealevel even during periods of sea-level stability. In the specific case of carbonate platform drowning, the special behavior of carbonate systems has been often related to a change in the ecology or biology of carbonate producers, in turn commonly linked to climate and/or environmental changes (Schlager, 1981(Schlager, , 2003Hallock and Schlager, 1986;Jenkyns, 1991;Mutti et al., 1997Mutti et al., , 2005Weissert et al., 1998;Wilson et al., 1998;Mutti and Hallock, 2003;Pomar et al., 2004;Föllmi and Godet, 2013;Godet et al., 2013;among others). In the Triassic of the Dolomites (northeastern Italy, Fig. 1A), sedimentary sequences are dominated by carbonates. ...
Sedimentary facies analysis aided by quantitative 3D georeferenced field data are applied to constrain the sequence stratigraphy of a complex stratigraphic interval in the Late Triassic of the Dolomites. This multidisciplinary approach was the key to disentangle the timing of climatic change vs. sea-level fluctuation and their effects on shallow water carbonate depositional systems. The “Carnian Pluvial Event”, a global episode of climate change worldwide documented at low latitudes, involved increased rainfall and possibly global warming. This climatic event begins before a drop of sea-level and caused the demise of microbial-dominated high-relief carbonate platforms that dominated the Dolomites region, and was followed by a period of coexistence of small microbial carbonate mounds and arenaceous skeletal-oolitic grainstones. A subsequent sea-level fall brought to the definitive disappearance of microbialites and shallow water carbonates switched to ramps dominated by oolitic-bioclastic grainstones. The crisis of early Carnian shallow water carbonate systems of the Dolomites generated a geological surface similar to a drowning unconformity, although no transgression occurred. As the high-relief microbial carbonate systems characterized by steep slopes switched to gently inclined oolitic-skeletal-siliciclastic ramps, basins were rapidly filled. The change of carbonate depositional systems was associated with an increase in siliciclastic input, in turn triggered by the onset of a humid climatic event and only later to a sea-level drop. This evolution of carbonate systems cannot be interpreted in the light of sea-level changes only: climate change, and consequent ecological changes in the main carbonate producing biotas, induced significant modifications in depositional geometries. This case study may serve as a conceptual model for the sedimentary evolution of carbonate systems subject to ecological crisis that do not evolve in platform drowning because, despite a drop in shallow water carbonate production, a combination of low subsidence and/or sea level drop maintains the platform top at shallow depth.
... However, publications on climatic controls on Oligocene sedimentation are few, albeit this was a time characterized by marked increase in global continental erosion (Clift 2010) and the development of a sizeable polar ice-sheet (DeConto et al. 2008). Climate change especially affected carbonate ecosystems in the restricted western Tethys, although Mediterranean carbonates remain less known than those of the Caribbean (Mutti et al. 2005) and the Indo-Pacific region (Wilson 2008). This study relies exclusively on carbonate platform sedimentation in order to infer climatic control on the western Tethys. ...
Cenozoic carbonate platforms in the central Mediterranean
region show distinct vertical changes in carbonate skeletal assemblages and
porosity characteristics that reflect shifts in environmental conditions affecting
the western Tethys. The Photozoan Association produced by carbonate ecosystems
adapted to low nutrient environments and the Heterozoan Association
favoured by mesotrophic conditions alternate through time over the Malta Platform
and nearby carbonate platforms, although not in phase with trans-Mediterranean
Oligocene carbonates. This anomaly reflects the transitional nature of
Cenozoic climate as well as continental convergence of the Tethyan margins.
Restricted conditions amplified the effect of nutrient flux from North African
fluvial systems, which was controlled by meridional shifts in the inter-tropical
convergence zone (ITCZ) precipitation belt. We model the climate–carbonate
interaction by comparing the global oxygen isotope proxy to ice volume and
meridional position of the ITCZ to changes in trophic level of carbonate ecosystems.
The results show that the development of Palaeogene Mediterranean
photozoan assemblages coincides with periods when the ITCZ had shifted away
from North Africa (as is the case presently), whereas the heterozoan assemblages
thrived during increased nutrient flux when the precipitation belt was
located over the Sahara. The climatic controls resulted in facies characteristics
that exert a fundamental influence on porosity in carbonate reservoirs.
In biogeography, vicariance and long-distance dispersal are often characterised as competing scenarios. However, they are related concepts, both relying on collective geological, ecological, and phylogenetic evidence. This is illustrated by freshwater fishes, which may immigrate to islands either when freshwater connections are temporarily present and later severed (vicariance), or by unusual means when ocean gaps are crossed (long-distance dispersal). Marine barriers have a strong filtering effect on freshwater fishes, limiting immigrants to those most capable of oceanic dispersal. The roles of vicariance and dispersal are debated for freshwater fishes of the Greater Antilles. We review three active hypotheses [Cretaceous vicariance, Greater Antilles-Aves Ridge (GAARlandia), long-distance dispersal] and propose long-distance dispersal to be an appropriate model due to limited support for freshwater fish use of landspans. Greater Antillean freshwater fishes have six potential source bioregions (defined from faunal similarity): Northern Gulf of México, Western Gulf of México, Maya Terrane, Chortís Block, Eastern Panam a, and Northern South America. Faunas of the Greater Antilles are composed of taxa immigrating from many of these bioregions, but there is strong compositional disharmony between island and mainland fish faunas (>90% of Antillean species are cyprinodontiforms, compared to <10% in Northern Gulf of México and Northern South America, and ≤50% elsewhere), consistent with a hypothesis of long-distance dispersal. Ancestral-area reconstruction analysis indicates there were 16 or 17 immigration events over the last 51 million years, 14 or 15 of these by cyprinodontiforms. Published divergence estimates and evidence available for each immigration event suggests they occurred at different times and by different pathways, possibly with rafts of vegetation discharged from rivers or washed to sea during storms. If so, ocean currents likely provide critical pathways for immigration when flowing from one landmass to another. On the other hand, currents create dispersal barriers when flowing perpendicularly between landmasses. In addition to high salinity tolerance, cyprinodontiforms collectively display a variety of adaptations that could enhance their ability to live with rafts (small body size, viviparity, low metabolism, amphibiousness, diapause, self-fertilisation). These adaptations likely also helped immigrants establish island populations after arrival and to persist long term thereafter. Cichlids may have used a pseudo bridge (Nicaragua Rise) to reach the Greater Antil-les. Gars (Lepisosteidae) may have crossed the Straits of Florida to Cuba, a relatively short crossing that is not a barrier to gene flow for several cyprinodontiform immigrants. Indeed, widespread distributions of Quaternary migrants (Cyprinodon, Gambusia, Kryptolebias), within the Greater Antilles and among neighbouring bioregions, imply that long-distance dispersal is not necessarily inhibitory for well-adapted species, even though it appears to be virtually impossible for all other freshwater fishes.
The interaction between bottom currents, platform-derived particles, and the bathymetric framework of isolated carbonate platforms can result in complex current-controlled depositional patterns, which are not entirely understood. The continuous supply and usually local deposition of carbonate particles around platforms, combined with the natural variations in the hydrodynamic regime at various depths, contribute significantly to the heterogeneity of carbonate contourite drifts. This thesis sheds light on the interplay between bottom currents and isolated carbonate platforms in two representative study areas. Moreover, this study presents a classification of carbonate contourite (sediment) drifts related to the architecture and sediment distribution of carbonate platforms based on seismic datasets, as well as the identification of the main driving mechanisms and depositional architecture. Two realms of isolated carbonate platforms were studied, which are located in the Bahamian and Maldivian archipelagos. Both are influenced by major ocean current systems, which were investigated to understand their effects on the depositional patterns. The study areas were targeted by geophysical methods during two scientific cruises, which produced dense grids of high-resolution seismic datasets, allowing new insights to be gained into the sedimentary dynamics of both archipelagos. To achieve the main objectives seismic and hydroacoustic datasets around isolated carbonate platforms were compiled and analyzed, combined with lithostratigraphic and chronological borehole data from multiple sites of the IODP expedition 359 and the ODP Site 1006. (Re-)Interpretation of multichannel seismic cross sections, subordinated echosounder sub-bottom profiling and bathymetric data as well as former inventory data revealed the history of oceanographic processes resulting in various geomorphologies of contourite drifts. The seismic data emphasize the diversity of the sedimentation pattern developed under the influence of long-term bottom current activity.
Here we describe and illustrate 31 Miocene corals species from the Siamaná and Jimol Formations that were collected over two expeditions in the Guajira basin, Colombia during 2011 and 2014. Corals include 25 species, derived from 15 different genera and 12 families. Six of them remain with open nomenclature. From the 25 species found in the study area, 88% are extinct and the remaining under endanger status. Most of the species are hermatypic components of the Scleractinian order, with the exception of a member of the Milleporidae family. The corals described are composed of typical taxa from the Oligocene-Miocene transition, during which they were important components in building fringing and patch reefs in the circum-Caribbean/Gulf of Mexico region. The presence of typical Oligocene coral taxa such as Agathiphyllia spp., Antiguastrea sp., and Diploastrea spp. from La Guajira extend the distribution of these genera into the Miocene, adding a more recent geological presence in the Southern Caribbean. Coral assemblages suggest a development in clear, calm and shallow waters, under oligotrophic conditions and only moderate physical disturbance. Our descriptions represent the first effort to characterize the taxonomy of fossilized corals in Colombia.
Here we describe and illustrate 31 Miocene corals species from the Siamaná and Jimol Formations that were collected over two expeditions in the Guajira basin, Colombia during 2011 and 2014. Corals include 25 species, derived from 15 different genera and 12 families. Six of them remain with open nomenclature. From the 25 species found in the study area, 88% are extinct and the remaining under endanger status. Most of the species are hermatypic components of the Scleractinian order, with the exception of a member of the Milleporidae family. The corals described are composed of typical taxa from the Oligocene-Miocene transition, during which they were important components in building fringing and patch reefs in the circum-Caribbean/Gulf of Mexico region. The presence of typical Oligocene coral taxa such as Agathiphyllia spp., Antiguastrea sp., and Diploastrea spp. from La Guajira extend the distribution of these genera into the Miocene, adding a more recent geological presence in the Southern Caribbean. Coral assemblages suggest a development in clear, calm and shallow waters, under oligotrophic conditions and only moderate physical disturbance. Our descriptions represent the first effort to characterize the taxonomy of fossilized corals in Colombia.
A long-standing question has been whether the Lower Nicaraguan Rise in the western Caribbean Sea represents thinned continental crust or is part of the Caribbean Large Igneous Province (CLIP). During the R/V Meteor cruise M81/2, the northeastern part of the Lower Nicaraguan Rise including the Hess Escarpment was extensively sampled. Only volcanic and carbonate rocks were recovered and no metamorphic rocks or rocks with continental crustal affinities, indicating that at least the uppermost basement is volcanic and belongs to a volcanic province, probably the CLIP. We provide a comprehensive geochemical dataset, including major and trace elements and Sr-Nd-Hf-Pb double spike isotope ratios, for the volcanic rocks. The basalts are geochemically subdivided into two groups: 1) depleted and 2) enriched. The majority belong to the depleted group with 6–9 wt% MgO and highly depleted incompatible element (e.g. (La/Yb)N = 0.15–0.76, (La/Sm)N = 0.21–0.65) compositions and depleted radiogenic isotope (e.g. εNdi = 8.9–11.0, εHfi = 13.6–16.5, ²⁰⁶Pb/²⁰⁴Pbi = 18.28–18.98) ratios. The subordinate enriched group basalts have 5–8 wt% MgO and were solely recovered from the lower part of the central Hess Escarpment. These rocks possess enriched incompatible element ((La/Sm)N = 1.15–1.60, (La/Yb)N = 1.40–2.57) and isotopic (εNdi = 7.52–8.34, εHfi = 12.6–12.9, ²⁰⁶Pb/²⁰⁴Pbi = 18.87–19.07) ratios resembling E-MORB. The depleted group is distinct from Pacific and Atlantic MORB based on combined ²⁰⁶Pb/²⁰⁴Pb, ¹⁴³Nd/¹⁴⁴Nd and ¹⁷⁶Hf/¹⁷⁷Hf data. It is similar, but not identical to the highly depleted Gorgona komatiites, thought to be generated during the CLIP event, and depleted Galápagos hotspot track lavas accreted to the Pacific margin of Central America. Ages of ~81 Ma from rocks drilled on the Hess Escarpment postdate the main CLIP phase (95-83 Ma), and indicate that at least the northeastern part of the Nicaraguan Rise formed during a later volcanic event. Lithospheric thinning after the main CLIP phase is suggested to have triggered upwelling of still anomalously hot, partially-melted or unmelted CLIP mantle material to form the younger depleted group of lavas. Our investigations imply that second-stage melting to generate depleted compositions during formation of oceanic large igneous provinces, as has been recently proposed for the Manihiki Plateau, is a more common process than originally thought.
The effect of rapid erosion on kinematic partitioning along transpressional plate margins is not well understood, particularly in highly erosive climates. The Blue Mountains restraining bend (BMRB) of eastern Jamaica, bound to the south by the left-lateral Enriquillo-Plantain Garden fault (EPGF), offers an opportunity to test the effects of highly erosive climatic conditions on a 30-km-wide restraining bend system. No previous thermochronometric data exists in Jamaica to describe the spatial or temporal pattern of rock uplift and how oblique (> 20°) plate motion is partitioned into vertical strain. To define the exhumation history, we measured apatite (n = 10) and zircon (n = 6) (U-Th)/He ages, ⁴⁰Ar/³⁹Ar (n = 2; amphibole and K-spar) ages, and U/Pb zircon (n = 2) crystallization ages. Late Cretaceous U/Pb and ⁴⁰Ar/³⁹Ar ages (74–68 Ma) indicate rapid cooling following shallow emplacement of plutons during north-south subduction along the Great Caribbean Arc. Early to middle Miocene zircon helium ages (19–14 Ma) along a vertical transect suggest exhumation and island emergence at ~ 0.2 mm/yr. Older zircon ages 10–15 km to the north (44–35 Ma) imply less rock uplift. Apatite helium ages are young (6–1 Ma) across the entire orogen, suggesting rapid exhumation of the BMRB since the late Miocene. These constraints are consistent with previous reports of restraining bend formation and early emergence of eastern Jamaica. An age-elevation relationship from a vertical transect implies an exhumation rate of 0.8 mm/yr, while calculated closure depths and thermal modeling suggests exhumation as rapid as 2 mm/yr. The rapid rock uplift rates in Jamaica are comparable to the most intense transpressive zones worldwide, despite the relatively slow (5–7 mm/yr) strike-slip rate. We hypothesize highly erosive conditions in Jamaica enable a higher fraction of plate motion to be accommodated by vertical deformation. Thus, strike-slip restraining bends may evolve differently depending on erosivity and local climate.
The evolution of the Cenozoic Circum-Caribbean shallow marine carbonate factories and ecosystems has been for long attributed to major global climatic and environmental changes. Although temporal variations in the Cenozoic shallow marine carbonate factories in this region seem to follow global trends, the potential effects of regional processes, such tectonic activity and local environmental change, on the evolution of the shallow marine carbonate factories are not well established. Here we present detailed sedimentologic and stratigraphic information from Middle Oligocene - Middle Miocene (Chattian-Burdigalian) shallow marine carbonate successions of the Siamana Formation in the Cocinetas sub-basin, Alta Guajira Basin, Guajira Peninsula, northern Colombia. We document the potential effects of regional tectonics and local environmental deterioration on the evolution of the Oligocene-Miocene tropical shallow marine carbonate factories along the SE Circum-Caribbean. Our results show that mixed heterozoan-photozoan biotic associations dominated the shallow marine carbonate factories during the Chattian, while purely photozoan biotic associations constituted the primary carbonate factory during the Aquitanian-Burdigalian transition. The Chattian mixed heterozoan/photozoan biotic association is associated with the development of mixed carbonate/siliciclastic shelves along which detached patchy reef areas occur. The onset of the Aquitanian-Burdigalian purely photozoan biotic associations parallels the increase in coral diversity as well as the occurence of rimmed/detached carbonate platforms in the northern part of the basin. The development of the rimmed/detached platforms coincides with a time of increased basin subsidence and increased silicilcastic input along the southernmost part of the basin. A significant change in the carbonate factory occurs in the Late Burdigalian, when purely heterozoan (rodalgal) biotic associations constituted the main shallow marine carbonate factory. This shift in the carbonate factory was favored by a major extensional component that resulted in subsidence and relative sea level rise along the Caribbean - South American margin. This extensional component is evidenced by the occurrence of normal faults that controlled the thickness and lateral extension of shallow marine rodalgal biostromes. The onset of the rodalgal biostromes, which elsewhere is associated with excellent carbonate reservoirs, also parallels the initiation of the Urumaco Trough and a further increase in silicilastic input toward the Cocinetas sub-basin. It also parallels a major tectonic reactivation along the Caribbean - South American plate boundary which resulted from the initial closure of the Panama Seaway.
The middle Miocene is an important time to understand modern global climate evolution and its consequences on marine systems. The Mid-Miocene Climatic Optimum (between 17.0 Ma and13.5 Ma), was the warmest time interval of the past 35 million years during which atmospheric CO2 concentrations were lower than today. In the Mid-Miocene Climatic Optimum a significant carbon cycle perturbation occurred, expressed as a last long-term positive carbon isotope shift, known in literature as the Monterey Carbon Isotope Excursion and recorded in open-ocean settings. In this work, the lower to middle Miocene carbon isotope records from three different domains of the Central Mediterranean are analyzed with the aim of identifying the local carbonate platform response to the major global carbon cycle perturbation of the Monterey event. Carbon and oxygen isotope ratios have been measured on samples belonging to three different stratigraphic sections, two of them representative of shallow water settings (Latium-Abruzzi and Apula Platforms), and the latter of a hemipelagic setting (Umbria–Marche Basin). A well-defined Monterey Carbon Isotope Excursion is recorded also in these shallow-water sections. Despite their expected problematic stratigraphic constraints, a reliable age model is provided by calcareous nannofossil biostratigraphy and strontium isotope stratigraphy. In both carbonate platform successions examined, the Monterey Carbon Isotope Excursion coincides with a spread of bryozoans over other carbonate-producing biota. The high productivity of the bryozoan dominated factory in the aphotic zone had an important control on the platform depositional profile. The high rates of sediment production in the deeper aphotic and oligophotic zones produced a depositional profile of a low-angle ramp. This article is protected by copyright. All rights reserved.
The Yangtze Platform drowned and was buried by pelagic facies and siliciclastic turbidites in western Guizhou Province during the Late Triassic, Carnian. The uppermost platform facies of the Ladinian Yangliujing Fm. consists of peritidal cyclic carbonate. Ladinian margin facies of the Longtou Fm. consist of grainstone and lenses of coral-Tubiphytes algal boundstone indicating highenergy shoals and patch reefs. The drowning horizon is laterally variable; it is either a sharp surface or a gradational shift to dark, nodular-bedded lime mudstone and wackestone of the Zhuganpo Fm. The contact lacks phosphatized or glauconitized hardgrounds that would indicate drowning by excess nutrient flux. Uppermost platform carbonates have a tropical photozoan biota and lack siliciclastic content indicating neither climate cooling nor siliciclastic flux played a role in drowning. The Zhuganpo Fm. contains a dominantly pelagic biota of ammonoids, planktonic bivalves, pseudoplanktonic crinoids, conodonts, and the marine reptile Keichousaurus. Rare bioturbation and benthic biota in the lower part indicate dysoxic conditions with an upward shift to anoxic conditions. The overlying Wayao Fm. is a pyritic, laminated, black argillaceous lime mudstone that grades to black shale with an exclusively pelagic fauna and marine reptile lagerstättes indicating anoxic deep-marine sedimentation. Syndepositional faults played a significant role in the evolution of the western sector of the Yangtze Platform and controlled three local, backstepped accommodation cycles in the Zhenfeng area. Faults that developed during the last accommodation cycle tip out at the drowning horizon and include a flower structure upon which a pinnacle reef developed while the rest of the platform drowned. Lateral variability in the drowning horizon and thickness of the post-drowning pelagic facies suggest that differential tectonic subsidence caused the platform to sink into deep water along faults. Magnetic susceptibility and paleomagnetic-reversal correlations demonstrate that the western sector of the platform drowned while shallow-marine, mixed carbonate siliciclastic sedimentation continued in the eastern sector which later terminated in shallow water by increasing siliciclastic flux. Starved black shale horizons in the basin indicate recurrent bottom-water anoxia. Elevated tracemetal concentrations in the pelagic facies of the Zhuganpo and Wayao formations indicate dysoxic to anoxic conditions and enhanced preservation of organic matter. Tectonic subsidence likely submerged the western sector into deep, toxic waters of the basin, killing benthic carbonate production. Previous studies have implicated the Carnian pluvial event as a cause of drowning of the Yangtze Platform and the shift to siliciclastic turbidites of the Laishike Fm., but the Yangtze Platform drowned earlier than western Tethys platforms and siliciclastics were already rapidly infilling the basin in the Anisian and Ladinian, indicating that the events are probably unrelated. Siliciclastics of the Laishike Fm. that overlapped and buried the platform only after the basin was filled are better interpreted as a response to tectonics than to a shift in climate.
Las islas de Providencia y Santa Catalina hacen parte del Departamento Archipiélago de San Andrés, Providencia y Santa Catalina, localizado en la cuenca Los Cayos en el Mar Caribe, al Noroeste de Colombia. Geológicamente las islas se ubican en el Rise de Nicaragua Inferior entre la Fractura de Pedro y el Escarpe de Hess (Rogers et al, 2007). Estas islas están conformadas principalmente por rocas volcánicas de carácter alcalino y calco-alcalino de edad mioceno medio y plioceno respectivamente. Se propone que la evolución geotectónica de la región parte de dos conos volcánicos erosionados cuya historia geológica está íntimamente relacionada con la evolución del Rise de Nicaragua y parte de la Placa Caribe (Rogers et al, 2007; Pindell y Kennan, 2001; Geister y Díaz, 2002). A la isla se le asocian unidades geomorfológicas de costas elevadas y bajas y en ella ocurren procesos morfodinámicos como caída de bloques, deslizamientos y erosión costera que podrían poner en riesgo la población. Económicamente se presenta explotación informal de canteras para agregados y existe la posibilidad de almacenamiento de hidrocarburos en la cuenca Los Cayos.
We used paleomagnetic results from Sites 998, 999, 1000, and 1001 to estimate the paleolatitude of the Caribbean region over the past 80 m.y. The data include remanence measurements of split-core sections (typically 1.5 m long) and discrete samples (6-12 cm3 in volume) from volcanic and sedimentary rocks. From these, we computed 15 new paleolatitude estimates for Sites 999 and 1001 on the Caribbean plate and three new paleolatitude estimates for Site 998 on the Cayman Rise, currently on the southern North American plate. One estimate from Site 1001 is based on 230 measurements made along split-core sections of basalt after demagnetization of 20-25 mT. The other 17 estimates are based on principal component analysis of demagnetization data from 438 discrete paleomagnetic samples from sedimentary units. Where necessary, the 18 new paleolatitude estimates are corrected for a polarity ambiguity bias that occurs when averaging paleomagnetic data from drill cores that have shallow inclinations and are not azimuthally oriented. We also investigated the contribution of additional biases that may arise from a compaction-related inclination error, which could affect the sedimentary units, though not the basalt units. Several lines of evidence, including the lack of a correlation between porosity (or water content) and inclination, indicate that the inclination error is small, if present at all. The results from Sites 999 and 1001 indicate that the Caribbean plate was 5°-15°south of its current position at ~80 Ma, possibly placing it directly over the equator in the Late Cretaceous. Although the data do not preclude changes in the rate of northward motion over the past 80 m.y., they are consistent with a constant northward progression at a rate of 18 km/m.y. Given the uncertainties in the data, rates of northward motion could be as low as 8 km/m.y. or as high as 22 km/m.y. These results are compatible with several existing models for the evolution of the Caribbean plate, including those that have the Caribbean plate originating in the Pacific Ocean west of subduction zones active in the Central American region during the Cretaceous, and those that have the Caribbean plate originating within the Central American region, though more than 1000 km west of its current position relative to North and South America.
Crystal size measurements have been carried out on tephra fall layers of Miocene to recent age from Sites 998, 999, and 1000 in the western Caribbean Sea. Maximum crystal size is used as a proxy for the grain size characteristics of the layers and an index of atmospheric dispersal from source eruptions. Crystal sizes range from 50 to 650 µm with the majority falling between 200 and 300 µm. All three sites exhibit a coarsening in the grain size of tephra layers with increasing age to the early Miocene that broadly correlates with an increase in the frequency of layers. Analysis of the present lower and upper level atmo-spheric circulation in the western Caribbean suggests that the layers were derived from source eruptions to the west of the sites somewhere in the Central American region. Minimum distances to these sources are of the order of 700 km. Crystal sizes in tephra layers at these distances are consistent with their derivation from energetic pyroclastic flow-forming eruptions that injected tephra to stratospheric levels by large-scale co-ignimbrite and plinian-style plumes. Coarsening of the layers during the Miocene peak of explosive volcanism cannot be attributed to any major change in paleowind intensity and is taken to represent the occurrence of more energetic eruptions that were able to disperse tephra over larger areas.
The eastern Cayman Trough preserves a record of the Late Cretaceous to Paleogene Caribbean history that is largely affected by Neogene strike-slip tectonics of the current plate boundary. We conducted an analysis of seismic data within the eastern Cayman Trough, based upon single and multi-channel seismic reflection profiles collected during the Seacarib II cruise in 1987 and the Casis cruise in 1992. These data show that the basement of the eastern Cayman Trough can be divided into four domains from east to west, with distinct morphologic and sedimentary character and inferred older to younger ages: (1) a province of rifted Mesozoic continental crust exhibiting seven parallel horst blocks striking northeast-southwest; (2) a continent-ocean transition between provinces 1 and 3 that exhibits seamounts, small hills, and sedimentary basins; (3) an Eocene oceanic crust with rough basement but smoother relief than the rifted crust; basement trends are roughly north-south and oblique to the northwest trend in domain 1, and (4) the northern Jamaica slope, which forms an east-west-trending slope, with northward-dipping strata that flank the three deeper water domains of the Cayman Trough. The domains are interpreted to be the product of the Eocene east-west opening of the Cayman Trough as a pull-apart basin in a left-lateral strike-slip setting. Closure of the 1100 km of Eocene and younger oceanic crust of the Cayman Trough places the fault-block province adjacent to the Belize margin of Central America. A Neogene phase of transpression has reactivated structures in the four domains, along with on-land structures described by previous authors in Jamaica. The proximity of the eastern margin of the Cayman Trough to petroliferous, continental rocks in Central America suggests an improved possibility of hydrocarbon potential. Unfortunately, sediment thicknesses of less than 1 km probably are not conducive to hydrocarbon formation.
The Nicaraguan Rise is an active tectonic structure in the western Caribbean. Carbonate accumulation on its platforms has not kept pace with relative Holocene sea-level rise, despite a tropical location remote from terrigenous sedimentation. Trophic resources apparently exceed levels favoring coral-reef development because sponge-algal communities dominate the drowning western platforms, in contrast to mixed coral-algal benthos on Pedro Bank and well- developed coral reefs along the north coast of Jamaica. Concentrations of biotic pigments in sea-surface waters show a corresponding west-east gradient; oceanic waters flowing over the western banks carry nearly twice as much biotic pigment as oceanic waters north of Jamaica. Sources enriching the western Caribbean are terrestrial runoff, upwelling off northern South America, and topographic upwelling over the Nicaraguan Rise. That relatively modest levels of trophic resources can suppress coral-reef development holds important implications for understanding carbonate platform drownings in the geologic record.
Sediment from Ocean Drilling Program Leg 165 was sampled in the Yucatan Basin, Colombian Basin, and Pedro Channel to determine the carbonate component (weight percent and mass accumulation rate (MAR)), deep and intermediate water chemistry (delta-13C), water mass connectivity (coccolith assemblages), and sea-level fluctuations (delta-18O), over an interval spanning the middle Miocene to the early late Miocene. The middle to late Miocene transition in the Caribbean was characterized by massive increase of carbonate dissolution. Five well-defined dissolution episodes between 12 and 10 Ma are characterized by dramatic reductions in carbonate content and MAR. This interval is referred to as the Caribbean carbonate crash. The term "carbonate crash" was borrowed from ODP Leg 138 published results (Lyle et al., 1995) due to similar observations in the eastern equatorial Pacific (EEP). The timing and periodicity of four of the five carbonate-dissolution episodes in the Caribbean basins appear to correspond to the late middle Miocene production peaks of the North Component Water (Wright and Miller, 1996), equivalent to the modern North Atlantic Deep Water (NADW). These findings suggest that the carbonate crash in the Caribbean and the EEP was caused by reorganization of the global thermohaline circulation. The re-establishment and intensification of the NADW production caused a concomitant influx of corrosive southern-sourced intermediate waters (analogous to the modern Antarctic Intermediate Water Mass) into the Caribbean. At the time of the late middle Miocene carbonate crash, the Caribbean became, and remains, an important pathway for the return flow of the global thermohaline oceanic circulation. The gradual closing of the Central American Seaway, simultaneous to the opening of seaways along the northern Nicaraguan Rise, disrupted the low latitude connection between the Atlantic and the eastern Pacific. As a direct consequence, the Caribbean Current was strengthened, and the Loop current was established. These conditions were favorable for the contemporaneous re-establishment of NADW. This reorganization of the global oceanic circulation at the middle to late Miocene transition is well recorded in the contrasting carbonate preservation pattern observed in the Caribbean basins, the EEP, and the Ceara Rise (equatorial Atlantic).
This research illustrates application of a fluid-inclusion technique for quantifying water depth of ancient carbonate platforms. Jurassic limestones of Monte Kumeta, Italy, were cemented with submarine calcite during a transition to carbonate platform termination. The calcite cements contain fluid inclusions consisting of Jurassic seawater and immiscible gas bubbles trapped during the growth and penecontemporaneous recrystallization of the cements. Crushing analysis indicates that gas bubbles are under pressures indicative of entrapment in water depths of 23 112 m. Assuming simple deepening and acknowledging chronostratigraphic errors, rates of relative rise in sea level were initially less than 7 m/m.y. followed by a rate of at least 33 m/m.y. These slow rates are evidence that the platform's demise was caused by an environmental perturbation other than rapid sea-level rise. The facies transitions and regional studies indicate that the perturbation resulted from nutrient excess or eutrophication in shallow water followed by deepening into ephemeral dysoxic waters at depths perhaps as shallow as 23 m.
δ18Obenthic values from Leg 194 Ocean
Drilling Program Sites 1192 and 1195 (drilled on the Marion Plateau)
were combined with deep-sea values to reconstruct the magnitude range of
the late middle Miocene sea-level fall (13.6 11.4 Ma). In parallel, an
estimate for the late middle Miocene sea-level fall was calculated from
the stratigraphic relationship identified during Leg 194 and the
structural relief of carbonate platforms that form the Marion Plateau.
Corrections for thermal subsidence induced by Late Cretaceous rifting,
flexural sediment loading, and sediment compaction were taken into
account. The response of the lithosphere to sediment loading was
considered for a range of effective elastic thicknesses (10 <
T e < 40 km). By overlapping the
sea-level range of both the deep-sea isotopes and the results from the
backstripping analysis, we demonstrate that the amplitude of the late
middle Miocene sea-level fall was 45 68 m (56.5 ± 11.5 m).
Including an estimate for sea-level variation using the
δ18Obenthic results from the subtropical
Marion Plateau, the range of sea-level fall is tightly constrained
between 45 and 55 m (50.0 ± 5.0 m). This result is the first
precise quantitative estimate for the amplitude of the late middle
Miocene eustatic fall that sidesteps the errors inherent in using
benthic foraminifera assemblages to predict paleo water depth. The
estimate also includes an error analysis for the flexural response of
the lithosphere to both water and sediment loads. Our result implies
that the extent of ice buildup in the Miocene was larger than previously
estimated, and conversely that the amount of cooling associated with
this event was less important.
Oligocene to middle Miocene sequence boundaries on the New Jersey coastal plain (Ocean Drilling Project Leg 150X) and continental slope (Ocean Drilling Project Leg 150) were dated by integrating strontium isotopic stratigraphy, magnetostratigraphy, and biostratigraphy (planktonic foraminifera, nannofossils, dinocysts, and diatoms). The ages of coastal plain unconformities and slope seismic reflectors (unconformities or stratal breaks with no discernible hiatuses) match the ages of global δ18O increases (inferred glacioeustatic lowerings) measured in deep-sea sites. These correlations confirm a causal link between coastal plain and slope sequence boundaries: both formed during global sea-level lowerings. The ages of New Jersey sequence boundaries and global δ18O increases also correlate well with the Exxon Production Research sea-level records of Haq et al. and Vail et al., validating and refining their compilations.
Geochemical, stratigraphic and palaeolatitudinal data from deep boreholes
drilled through Pacific guyots—flat-topped seamounts—help to explain
the drowning of these Cretaceous shallow-water carbonate platforms that once
thrived through the accumulation of biogenic and inorganic calcium carbonate
sediment in mid-oceanic regions. The platforms drowned sequentially over a
60-million-year interval while they were being transported northward by Pacific
plate motion through a narrow equatorial zone (0–10° S).
Such platforms were apparently resistant to the effects of Cretaceous oceanic
anoxic events. Although the mechanism responsible for drowning remains unknown,
the tropics have not always been the refuge for atolls that they are today.
Oligocene to middle Miocene sequence boundaries on the New Jersey coastal plain (Ocean Drilling Project Leg 150X) and continental slope (Ocean Drilling Project Leg 150) were dated by integrating strontium isotopic stratigraphy, magnetostratigraphy, and biostratigraphy (planktonic foraminifera, nannofossils, dinocysts, and diatoms). the ages of coastal plain unconformities and slope seismic reflectors (unconformities or stratal breaks with no discernible hiatuses) match the ages of global delta(18)O increases (inferred glacioeustatic lowerings) measured in deep-sea sites. These correlations confirm a causal link between coastal plain and slope sequence boundaries: both formed during global sea-level lowerings, The ages of New Jersey sequence boundaries and global delta(18)O increases also correlate well with the Exxon Production Research sea-level records of Haq et al, and Vail et al., validating and refining their compilations.
The New Jersey Sea Level Transect was designed to evaluate the relationships among global sea level (eustatic) change, unconformity-bounded sequences, and variations in subsidence, sediment supply, and climate on a passive continental margin. By sampling and dating Cenozoic strata from coastal plain and continental slope locations, we show that sequence boundaries correlate (within +/-0.5 myr) regionally (onshore-offshore) and interregionally (New Jersey-Alabama-Bahamas), implicating a global cause. Sequence boundaries correlate with delta18O increases for at least the past 42 myr, consistent with an ice volume (glacioeustatic) control, although a causal relationship is not required because of uncertainties in ages and correlations. Evidence for a causal connection is provided by preliminary Miocene data from slope Site 904 that directly link delta18O increases with sequence boundaries. We conclude that variation in the size of ice sheets has been a primary control on the formation of sequence boundaries since ~42 Ma. We speculate that prior to this, the growth and decay of small ice sheets caused small-amplitude sea level changes (
Evaluates compiled d13C data from benthic foraminifera in order to define deepwater production for Miocene. Defines two modes of bottom water production: (1) Southern Component Water during earliest Miocene (24-20 Ma) and early middle Miocene (15-12.5 Ma) and (2) Northern Component Water, Tethyan water, and SCW (20-16 Ma) and NCW, SWC (12.5-10 Ma). Re-evaluates silica switch hypothesis and concludes that aging water in Pacific supports deepwater production model. Argues that data used for origninal hypothesis contained siliceous forms susceptable to dissolution. Diatoms outside upwelling zones represent a better control. Defines a method from tight stratigraphic control.
Recent high-resolution seismic reflection profiling, sediment sampling, SCUBA observations and Landsat imagery show that Cay Sal Bank (CSB) has very limited reef development, no active sand shoals, few islands, a thin to non-existent sedimentary cover and a relatively deep margin (20–30 m) and shelf lagoon system (10–20 m), Windward and leeward margins can be discerned, but their general development is poor when compared to the shallower, more active margins of Little Bahama Bank (LBB) and Great Bahama Bank (GBB).
The Bridgeboro Limestone, a rhodolith- and coral-bearing limestone in southwestern Georgia, has been assigned to the Vicksburgian Stage (Lower Oligocene) of the Gulf Coast based on the occurrence of the bivalves Chlamys ( Anatipopecten ) anatipes (Morton) and C. ( Lyropecten ) duncanensis Mansfield. This assignment is further substantiated by the recent recognition of the distinctive bryozoan Tubucellaria vicksburgica Canu and Bassler. The Bridgeboro also contains the larger foraminifera Lepidocyclina ( Lepidocyclina ) mantelli (Morton), L. ( Nephrolepidina ) yurnagunensis Cushman, and L. ( Eulepidina ) undosa Cushman, an assemblage indicative of the Lepidocylina (s.s.) subzone of the Eulepidina Zone of Early Oligocene age. These foraminifera are also characteristic of the Duncan Church beds of the Florida panhandle, and an assemblage of isolepidine and eulepidine Lepidocyclina also occurs in the Glendon Limestone of Alabama. On the basis of larger foraminifera, macroin vertebrates, and physical stratigraphic relationships, we propose that the Bridgeboro, Duncan Church, and Glendon are biostratigraphically and lithostratigraphically correlative. The Glendon Limestone has been previously assigned to nannoplankton zone NP22, and also occurs within the Cassigerinella chipolensis – Pseudohastigerina micra planktonic foraminiferal zone, both of Early Oligocene age. Based on correlation with the Glendon, the age of the Bridgeboro is thus Early Oligocene (Rupelian), middle Vicksburgian.
Topographic features of submerged oceanic areas have received less attention from geographers than have inhabited islands or economically important fishing banks, with the result that geographic names are slow to become established and some areas may have several designations. This has been the case in the western Caribbean where the suboceanic ridge extending eastward from Central America to Jamaica and beyond—the Nicaragua Rise—is called by different names on recently published maps. Current practice seems to favor the direct use of a nearby land name for the oceanic feature without an adjective modification. Examples are Colombia Basin, Barbados Ridge, Grenada Trough, and Puerto Rico Trench. Where a name has not already become firmly established, this practice will be followed here.
The major part of the Bahama Banks is covered with a mantle of sands composed of calcium carbonate. They rest on a basement of similar sediment which has been consolidated into limestone by the subaerial deposition of calcite cement. Along the extreme edges of the Banks, the sand consists of the debris of neritic organic skeletons; elsewhere it is predominantly non-skeletal, and composed of grains of cryptocrystalline aragonite. These non-skeletal sand grains have hitherto been regarded as a break-down product of the limestones, but the present study, based on the Ragged Island area in the southeast part of the Great Bahama Bank, disproves this, and shows that such derived grains are rare in the recent bottom sediment. The sand grains are instead considered to be primary: they have formed, and are now forming, by the physico-chemical and bio-chemical extraction of aragonite from the sea water, which is saturated or supersaturated with calcium carbonate. The grains develop by the progressive aragonitic cementation of friable aggregates of calcareous silt particles. Further cementation tends to join the grains into lumps, in which an outer dense cryptocrystalline layer commonly allows the slower growth of larger aragonite prisms in the interior parts. The habit and surface texture of the lumps undergo a sequence of changes when traced from the ocean edge toward the interior of the Banks. Corrasion prevents excessive lump growth, and the typical bottom sediment is a well sorted medium-grade sand. The traces of calcareous mud in the sands contain no evidence of "drewite" needles, which are restricted to the protected "shelf lagoons" west of Andros and Abaco Islands. The controlling factor in the formation and distribution of the sands is the tidal currents of cooler oceanic water which sweep onto the Banks with velocities diminishing toward the interior, precipitating calcium carbonate as the water warms and evaporates. Sedimentation is therefore most rapid along the borders of the Banks. Aided by sea-level changes, this has led to the building of lines of elongate cays, parallel, and close to the ocean edge, making each Bank a gigantic atoll. Superficial aragonite ooliths develop on the protected beaches of the cays, and in the track of currents through the inter-cay channels. East of the "Tongue of the Ocean" and elsewhere close to End_Page 1------------------------------ the borders of the Banks, there are extensive areas where the sand is swept into a curvilinear pattern-work of submarine dunes, which occasionally adopt barchan shape. These have not been sampled, but are considered favorable for the formation of true, as opposed to superficial, ooliths. Evidence from the well drilled to a depth of 14,587 feet on Andros Island suggests that calcareous sands, similar to the recent deposits, have played a large part in building the Bahama Banks.
These banks currently are healthy producers of large volumes of periplatform sediments (fine aragonite and magnesian calcite), which are exported almost entirely to the deep surrounding slopes. These sediments, which were deposited during the past 9000-10 000 years, form periplatform wedges on the middle and upper slopes, which are seen clearly on 3.5 kHz seismic profiles. Radiocarbon ages of the wedge surface sediment range between 230 and 610 YBP and provide clear evidence for the contemporaneous production of sediments on the shallow bank and shelf and their instantaneous export to the upper slopes. -from Authors
This bank is one of several small, detached platforms upon which carbonate accretion is failing to keep pace with Holocene sea-level rise. High-resolution seismic profiling, sediment sampling, SCUBA-diver observations, and dredge hauls show that this relatively deep (10 to 40m) bank is bounded by steep escarpments, lacks coral-reefs, and has few islands and minimal Holocene sediment cover. Hardgrounds populated by brown algae and sponges predominate in the southeastern sector; sediments are thin and coarse-grained. Factors limiting Holocene sediment accretion on Serranilla bank include the platform's small size, strong currents that promote off-bank sediment transport, rapid flooding during Holocene sea-level rise, lack of active frame-building benthic communities, and ubiquitous bioerosion. -from Authors
Suggests that oceanographic events can generate major seismic stratigraphic breaks that result in the succession of depositional sequences and systems along continental margins and that they may be as important as eustatic oscillations. Data also suggest that 'modern' Loop Current/Gulf Stream circulation was initiated in the middle Miocene, controlled by tectono-oceanographic and/or climatic processes. The challenge now is to identify seismic stratigraphic-scale oceanographic events in the rock record, differentiate them from eustatic responses, and evaluate their paleoenvironmental significance. -from Authors
Data in the tropical Indian Ocean show an excursion of d13C signals toward heavier values, lasting for about 4 million years. The excursion terminates at approximately 13.5 Ma. The Chron 16 Carbon shift coincides with the cessation of an early Miocene warming trend. Hypothesizes that a feedback loop was established. An initial increase in the planetary temperature gradient started thermocline development which led to organic carbon extraction at the ocean margins which resulted in a drop in atmospheric carbon dioxide concentration. Concomitant cooling (reverse greenhouse effect) strengthened thermocline development, leading to further cooling. The loop was broken when available nutrients were used up. -from Authors
About half the Caribbean hermatypic corals died out in the Caribbean during the latest Oligocene through Early Miocene, about 24-16 Ma. The majority of those corals that died out in the Caribbean are extant in the Indo-Pacific, ie they suffered geographic restriction, rather than extinction. The coral and coral associate faunas of three Upper Oligocene and three Middle Miocene fossil reefs in western Puerto Rico were compared. Nearly all coral genera tolerant of both turbidity and cool water survived. Extensive Miocene phosphorites throughout the Caribbean indicate enhanced upwelling in the region during the time of the coral extinction/restriction. Enhanced upwelling could account for the extinction/restriction by generally increasing nutrient levels and cooling Caribbean coastal surface waters. -from Authors
Because rates of carbonate production and bioerosion are similar, even modest increases in nutrient avalability can shift a reef community from net production to net erosion. In the geologic record, drowned reefs and carbonate platforms typically exhibit evidence of nondeposition, bioerosion, and reduced redox potential, which indicate excess nutrient availability during drowning. -from Authors
Patterns of morphological variation were compared among clades of scleractinian reef-corals, which differ in degree of sexuality, to determine if species discreteness and cohesiveness differ between predominantly biparental and predominantly uniparental reproducers. First, canonical discriminant analysis and sheared principal component analyses were used to analyze morphological variation within and among local populations of species of Porites, Siderastrea, and Montastraea from environmentally distinct habitats near Discovery Bay, Jamaica. The results show that variation is reduced within populations of Montastraea annularis and Porites astreoides, two species which frequently reproduce uniparentally. No clear relationship was found between degree of outcrossing and differentiation among populations. Next, to compare discreteness of species, similar analyses were made among living species within these clades. The results suggest that species are more discrete in the biparental genus Siderastrea and less discrete in eastern Pacific Pocillopora, a genus in which reproduction is largely uniparental. Analyses of fossils of these genera from the Neogene of the Dominican Republic confirm that species are more discrete in Siderastrea. Multivariate analyses of temporal variation within each species through the five million year Dominican Republic sequence, as well as over the past 30 million years throughout the Caribbean, further show that stasis appears to be the rule regardless of degree of outcrossing. Thus, despite clonal population structures, coral species do form discrete evolutionary units over geologic time. Lastly, clade diversity within any one time interval was found to be roughly comparable in biparental and uniparental reproducers, although speciation and extinction rates appear slightly higher in uniparental clades in association with extinction events. In conclusion, other than possible reduced divergence during speciation, uniparental reproduction appears to have little longterm influence on the phylogenies of these corals.
In the central Mediterranean area, a major, second-order transgressive event spanning from the Burdigalian to the Serravallian is recorded by the widespread deposition of deeper-water facies on carbonate shelves and is matched to a large extent by changes in carbonate facies, including the sudden disappearance of corals and coral reefs and the corresponding rise in the abundance of temperate and cool-water carbonate facies. Two sections from the Maiella platform margin in the southern Apennines and the Hyblean Plateau in Sicily provide us with time series based on oxygen and carbon isotopes and detailed biostratigraphic and strontium isotope ages of unprecedented resolution to compare these facies changes to the global Neogene cooling trends and to the paleoceanographic conditions existing at the time in the Mediterranean area.
An evaluation of the timing of facies change indicates that the major cooling interval in the Neogene, between 14 and 12 Ma, postdates the change from tropical to temperate carbonate facies in the Mediterranean, which began at approximately 20 Ma. Our oxygen isotope record from the Hyblean Plateau suggests relatively cool temperatures during the Serravallian (within biozones N10–N12) with progressive warming within biozone N11 (11.9–11.8 Ma). This signature is opposite to the one recorded in pelagic sections in other locations of the world and is interpreted to reflect regional conditions within the Mediterranean, as after 20 Ma, the connection to the Indian Ocean became closed or reduced to a very shallow sill, which prevented the outflow and inflow of intermediate and deeper waters.
The second-order transgressive event in the central Mediterranean coincides with an increase in the δ¹³C values of skeletal carbonates. These isotope data, combined with biotic evidence, suggest increased productivity of surface waters during the transgressive event. The onset of this event predates by approximately 3 m.y. the major positive carbon isotope excursion recorded worldwide in pelagic sections (the Monterey event); its termination coincides with the end of the Monterey excursion.
Our data indicate how variations in water temperatures, coupled with drastic changes in water circulation, severely affected rates of carbonate production during the deposition of a second-order sequence and had the effect of accentuating the transgressive trend within the sequences. Rates of carbonate production reached a minimum during the transgressive and early-highstand systems tracts. This low production was not linked to a decrease in the size of the carbonate-producing area along the depositional ramp but rather to changes in production rates due to environmental change. A better understanding of the response of carbonate facies to paleoceanographic changes needs to be developed, so that these changes can be used to predict sequence stratigraphic architecture in a given time slice and to better estimate the reliability of the sea-level signature preserved in carbonate sequences.
A global synthesis of Miocene benthic foraminiferal carbon and oxygen isotopic and faunal abundance data indicates that Miocene thermohaline circulation evolved through three regimes corresponding approximately to early, middle, and late Miocene times. There is evidence for major qualitative differences between the circulation of the modern ocean and the Miocene ocean prior to 11 Ma. The distribution pattern of siliceous oozes in Miocene sediments is consistent with our proposed reconstruction of thermohaline circulation. Major changes which occurred in circulation during the middle Miocene were probably related to the closing of the Tethys and may have contributed to rapid middle Miocene growth of the Antarctic ice cap. -from Authors
At Deep Sea Drilling Project sites 289 and 574, the mid-Miocene carbon isotope records are characterized by an interval of high δ13C values between 17 and 13.5 Ma upon which are superimposed a series of periodic or quasi-periodic fluctuations in δ13C values. These fluctuations have a period of approximately 440 kyr, suggestive of the 413 kyr cycle predicted by Milankovitch theory. We have assigned an absolute chronology, based on biostratigraphic and magneto-biostratigraphic datum levels, to the isotope stratigraphy and have used that chronology to correlate unconformities, seismic reflectors, carbonate minima, and dissolution intervals. The chronology indicates that the major mid-Miocene deepwater cooling/ice volume expansion took 2 m.y. and was not abrupt as had been reported previously. The cooling was not monotonic, and the 2 m.y. interval included an episode of especially rapid cooling as well as a brief return to warmer conditions before the final phase of the cooling period. -from Authors
The late Quaternary sedimentary record in periplatform oozes and muds deposited on the northern Nicaragua Rise results from the interplay of four main controls: 1) input of pelagic carbonates and bank-derived fine aragonite and magnesian calcite; 2) input of siliciclastic sediments; 3) dispersal and removal of sediments by the Caribbean Current; and 4) partial seafloor dissolution of metastable carbonates. High accumulation rates of the calcite coarse sediment fraction throughout the study area demonstrate that planktonic foraminiferal productivity peaked during interglacial stages. Neritic carbonate productivity also peaked during interglacial stages, when bank and shelf tops along the Nicaragua Rise were submerged within the photic zone. A large volume of siliciclastic sediments, transported from the coastal area of South America and the eastern and western regions of Jamaica, were deposited during glacial stages within the eastern and western deep extensions of Walton Basin. Cores in water depths exceeding 1100m display during interglacial stages lower aragonite accumulation rates, indicating that some bank-derived aragonite and magnesian calcite has been partially removed by seafloor dissolution in areas from water depths exceeding 1100m. -after Authors
The enormous phosphorite deposits of the southeastern United States indicate intense upwelling but contain small amounts of organic carbon. The authors propose that deposition of organic-rich sediment on continental shelves in the southeastern United States and elsewhere during marine transgressions in the late Oligocene and early to middle Miocene resulted in global positive δ¹³C shifts and the formation of early diagenetic phosphorite. Multiple reworking and supergene weathering from subaerial exposure during Miocene marine regressions oxidized most of the organic carbon and resulted in the return of δ¹³C to its preexcursion value. The estimated phosphorite content of the southeastern United States requires sufficient organic carbon burial (>10¹ⵠkg carbon) to support a 1{per thousand} δ¹³C excursions, sea-level fluctuations, organic carbon burial, phosphogenic episodes, and possibly global cooling during the Cenozoic.
Pedro Channel is the deepest, central-most seaway on the northern Nicaragua Rise. A revised bathymetric map illustrates a seafloor dissected by numerous canyons and gullies as well as portions of a drowned carbonate bank with keep-up bank morphology. The 3.5 kHz echogram data interpretation in Pedro Channel indicates the banks provide both a line and point source of sediment to the channel floor. Concentric facies belts along the bank margins illustrate the line source concept. Localized zones of coarser-grained deposits at the bases of canyons along the bank margins depict the point source concept. The synthetic seismograms for ODP Site 1000 have low correlation coefficients (0.321). Visual correlation of the synthetic seismogram with SCS data indicates a good correlation of seismic facies with various lithologic intervals. An interpretation of SCCS and MCS data reveals that periplatform sedimentation has dominated Pedro Channel from the early Miocene to recent. Dredge haul analysis suggests that a neritic carbonate bank drowned partially in the middle Oligocene and finally in the early Miocene. Erosion affects the edges of this drowned bank in the middle Miocene. Faults in Pedro Channel illustrate characteristics typical of sinistral strike-slip faults including vertical to sub-vertical faults, faults that splay upward, forced folds, and linear fault traces in map view. ODP Site 998 was selected over a small portion of the Cayman Rise on a small topographic high. Synthetic seismograms for ODP Site 998 have low correlation coefficients (0.168). Despite the low correlation coefficients, turbidite-rich core intervals correlate with SCS intervals having low continuity seismic reflectors. The predominantly pelagic sedimentation at this Site results in a generally continuous seismic reflection character. ODP Site 1001 is located just north of the Hess Escarpment. Synthetic seismograms have low correlation coefficients (0.335), but do permit correlation of SCS Asp{''} and Bsp{''} horizons with an Eocene-Miocene unconformity and basaltic basement respectively. Hydrosweep data indicates that the Hess Escarpment is dissected by numerous canyons incising along faults. The northwest trending normal faults are suggestive of dextral strike-slip motion.
The Serranilla Basin is a flat-floored, semi-circular bathymetric depression (100×100 km; 1100–1200 m deep) at the western end of the northern Nicaragua Rise (NNR) in the Caribbean Sea. It is bound to the north by the Cayman Trough, an area of active sea floor spreading, and is part of the Northern Caribbean Plate Boundary Zone (NCPBZ). Single-channel, high-resolution seismic data were calibrated to rock dredges and ODP Site 1000 to define the geologic evolution and attempt to tie sequence formation within the basin to tectonic developments in this part of the Caribbean. Five seismic sequences were identified within the basin. The two lower sequences (A and B) are interpreted as neritic and shallow periplatform deposits which infill three distinct basins that make up the early to late Miocene Serranilla Basin. The three upper sequences (C through E) are interpreted as periplatform and pelagic deposits interspersed with turbidites, and in some areas, megabreccias. Faulting is prevalent in sequences A through C in the central basin, and becomes progressively younger toward the south, disrupting the seafloor in places and perhaps indicating renewed activity along the Pedro Fracture Zone. The timing of sequence boundary formation has been correlated to tectonic activity along the NCPBZ and closure of the Central American Seaway. Possible mechanisms of sequence boundary formation include tectonic tilting within the basin in conjunction with increased turbidite deposition, carbonate platform drowning and subsequent back-stepping associated with circulation changes resulting from tectonic `gateway' closure, and megabreccia deposition associated with bank demise. Although a direct genetic relationship is not proven, regional tectonic changes are considered more important than eustatic sea-level changes in controlling depositional sequence formation in the Serranilla Basin.
The Miami Terrace is a drowned early to middle Tertiary carbonate platform, the outer margin of which has been deeply incised by submarine erosion subsequent to deposition of the limestone terrace. This interpretation is based on the study of high-resolution seismic reflection profiles, rock dredge samples, observations from deep-diving submersibles, and correlation with drill-hole data. The karstic upper terrace (200–375 m) yields limestones and dolostones of early middle Miocene age that have shallow-shelf affinities. Truncated beds of an eastward-dipping deeper-water slope facies are exposed on the upper surface of the erosional lower terrace at 600–700 m. The upper and lower terraces are separated by a discontinuous ridge, probably a drowned Miocene, or post-Miocene bank margin complex. Both terraces and the ridge are capped by dense conglomeratic phosphorites and phosphatic limestones. Phosphorite nodules are more common on the lower terrace whereas the upper terrace yields large phosphorite slabs as well as shark's teeth and bones of marine mammals.
The rule that sedimentation rates decrease as the time interval increases has been examined by a procedure that avoids the mathematical problem of plotting a variable, time, against its inverse. The test confirms that the scaling trend has real physical meaning. In the time range of 10-1 108 yr, sedimentation rates change roughly proportionally to the inverse of the square root of time. This report proposes and evaluates the hypothesis that the growth potential of reefs and carbonate platforms follows the same scaling trend. The trend implies that a growth of 104 mum/yr sustained over 103 yr, an upper limit of reef growth in the Holocene, translates into 102 mum/yr sustained over 107 yr. Decrease of the growth potential with increasing time solves the paradox of drowned platforms if the decrease results largely from environmental factors and not simply from increase of the time fraction of subaerial exposure.
A total of 53 calcareous nannofossil datums were detected in Quaternary and Neogene sections recovered during Ocean Drilling Program Leg 165 in the Caribbean Sea. Most of the low-latitude nannofossil zonal markers of Okada and Bukry could be determined at all of the sites. Additionally, size distribution patterns of specimens of Reticulofenestra, a common genus in Neogene and Quaternary sed- iments, were examined to interpret the biostratigraphic utility of changes in size.
The Northern Nicaragua Rise (NNR) is comprised today of the eastern Honduras/Nicaragua and southern Jamaica carbonate shelves, and a series of relatively small detached carbonate banks (i.e., Pedro, Rosalind, Serranilla, Diriangen, and Bawika Banks) separated from each other by intervening basins and seaways. The NNR basins and seaways, because of their common north trending orientation, have been previously interpreted as Paleocene, Eocene, and possibly Oligocene rifts, becoming progressively younger from the eastern to the western part of NNR. Results from three recent (1988 and 1992) high resolution seismic surveys within these major seaways and basins, (1) Walton Basin, (2) Pedro Channel, and (3) seaways and Serranilla Basin on the western side of the NNR, show that the present bank and basin configuration evolved from a once continuous megabank that covered the entire length of the NNR, including the Island of Jamaica from Eocene through early Miocene times. In the late middle ( ) Miocene, this megabank progressively broke up into a series of smaller banks, basins and seaways, mainly as the result of tectonic movements related to the overall strike-slip displacement within the North American and Caribbean Plate Boundary Zone of the Cayman Trough. At the same time (late middle Miocene), the most eastern portion of the megabank was uplifted and today forms most of central and south Jamaica. The timing of the megabank segmentation has tentatively been constrained by dating several blocks of shallow water limestone dredged from parts of the megabank outcropping on the sea floor of different seaways.
Oxygen isotopic compositions of the tests of planktonic foraminifera from several Deep Sea Drilling Project sites provide a general picture of low-latitude marine temperatures from Maastrichtian time to the present. Bottom temperatures determined from the isotopic compositions of benthonic foraminifera are interpreted as being indicative of high-latitude surface temperatures. Prior to the beginning of middle Miocene time, high- and low-latitude temperatures changed in parallel fashion. Following an apparently small and short-lived drop in temperature near the Tertiary-Cretaceous boundary, temperatures remained warm and relatively constant through Paleocene and early and middle Eocene time; bottom temperatures then were on the order of 12°C. A sharp temperature drop in late Eocene time was followed by a more gradual lowering of temperature, culminating in a late Oligocene high-latitude temperature minimum of about 4°C. A temperature rise through early Miocene time was followed in middle Miocene time by a sudden divergence of high- and low-latitude temperatures: high-latitude temperatures dropped dramatically, perhaps corresponding to the onset of major glaciation in Antarctica, but low-latitude temperatures remained constant or perhaps increased. This uncoupling of high-and low-latitude temperatures is postulated to be related to the establishment of a circum-Antarctic circulation similar to that of today. A further drop in high-latitude temperatures in late Pliocene time probably signaled the onset of a major increase in polar glaciation, including extensive sea-ice formation. Early Miocene, small-amplitude (1 per mil) sympathetic fluctuations in isotopic compositions of planktonic and benthonic foraminifera have been identified. These have a period of several hundred thousand years. Superimposed upon these are much more rapid and smaller fluctuations (0.2 to 0.5 per mil) with a period of about 80,000 to 90,000 yr. This is similar to the period observed for Pleistocene isotopic temperature fluctuations. In low latitudes, much smaller vertical temperature gradients seem to have existed during Maastrichtian and Paleogene time than exist at present. The absence of a sharply defined thermocline during early Tertiary time is also suggested.
Previous studies of benthic foraminiferal isotopic composition have
demonstrated that a latest Eocene-earliest Oligocene benthic
foraminiferal δ18O increase occurred in the Pacific,
Southern and Atlantic Oceans1-9. A Middle Miocene
δ18O increase has been noted in the Pacific, Southern
and South Atlantic Oceans1-3,7,10,11 and tentatively
identified in the North Atlantic12,13. Due to the incomplete
nature of the North Atlantic stratigraphical record14,15,
however, the Oligocene to Middle Miocene isotopic record of this ocean
is poorly understood. In the modern ocean, the North Atlantic and its
marginal seas has a critical role in abyssal circulation, influencing
deep- and bottom-water hydrography as far away as the North
Pacific16-18. We now report oxygen isotope measurements on
Oligocene to Middle Miocene (12-36 Myr BP) benthic foraminifera in the
western North Atlantic which show two periods of enriched 18O
values: early Oligocene and early Middle Miocene. These enriched
intervals are interpreted as resulting, in part, from the build-up of
continental ice sheets. The Oligocene to Middle Miocene
δ13C record shows three cycles of enrichment and
depletion of large enough magnitude to be useful for
time-Stratigraphical correlations. Within the biostratigraphical age
resolution, δ18O and δ13C records
correlate with records from other oceans, helping to establish a useful
Tertiary isotopic stratigraphy. An Atlantic-Pacific
δ13C contrast of 0.3-0.9‰ during the latest
Oligocene to Middle Miocene (12-26 Myr BP) indicates North Atlantic deep
and bottom-water production analogous to modern North Atlantic deep
water (NADW).
Previous interpretation of the Tertiary delta 18O record of planktic and benthic foraminifers has emphasized comparison to the modern ocean, assumed an ice-free world prior to middle Miocene time, and thereby calculated surprisingly cool temperatures for the tropical sea surface. We propose an alternative interpretation, which compares Tertiary data to average late Pleistocene, assumes constant tropical sea-surface temperature, and thereby estimates global ice volume. This approach suggests that Earth has had a significant ice budget (and therefore glacio-eustatic sea-level fluctuations) at least since Eocene and perhaps even throughout much of Cretaceous time. -Authors
Recently reported radioisotopic dates and magnetic anomaly spacings have made it evident that modification is required for the age calibrations for the geomagnetic polarity timescale of Cande and Kent (1992) at the Cretaceous/Paleogene boundary and in the Pliocene. An adjusted geomagnetic reversal chronology for the Late Cretaceous and Cenozoic is presented that is consistent with astrochronology in the Pleistocene and Pliocene and with a new timescale for the Mesozoic.
A high-quality δ18O record has been obtained from a deep sea core in the Somali Basin in a water depth of 4020 m, well below the foraminiferal lysocline, by analyzing bulk sediment instead of picked foraminifera. In some areas this may be a valuable tool for extending the applicability of the δ18O stratigraphy, for obtaining data by a less labor-intensive procedure, and for conserving valuable core material. Additionally, we draw attention to the need for more data on δ13C in bulk carbonate if we are to fully utilize the ocean δ13C record either in relation to long-term global carbon budget, or in relation to changes in carbon cycling in the ocean and its effect on atmospheric pCO2.
To view Cenozoic ice-volume and ocean-temperature history, a composite δ18O time series was constructed for tropical shallow-dwelling planktonic foraminifers and for deep-water benthic foraminifers. We conclude that Cenozoic benthic δ18O primarily reflect considerable deep-ocean temperature variation and that tropical planktonic δ18O afford the best record of Cenozoic ice volume. The planktonic composite indicates the presence of a significant ice budget for the past 40 m.y. The difference between the benthic and planktonic δ18O composites suggests that low-latitude production of warm saline bottom water dominated Tertiary thermohaline circulation. -Authors
Shallow-water carbonate platforms and reefs are drowned when tectonic subsidence or rising sea level outpaces carbonate accumulation, and benthonic carbonate production ceases. Drowned platforms are common in the geologic record, but they present a paradox if one considers rates of processes involved. The growth potential of reefs exceeds any relative rise of sea level caused by long-term processes in the geologic record. Rapid pulses of relative rise of sea level or reduction of benthic growth by deterioration of the environment remain the only plausible explanations of drowning. The geologic record shows examples of both of these processes. - from Author
Oceanwide or global changes in the δ¹³C of dissolved marine HCO⁻3 during Tertiary time are now well established, and these must reflect changes in the global cycling of carbon. Miocene Pacific benthic foraminiferal δ¹³C values are well correlated with marine onlap-offlap. The differences among δ¹³C values of separated benthic species from single sediment samples co-vary with biological productivity in the overlying surface waters. -from Authors
Carbonate platform drownings are frequent, often synchronous global occurrences, yet explanations for these world-wide events remain unsatisfactory. In the Central Apennines, Lower and Middle Miocene carbonate rocks deposited on a ‘temperate’ ramp in the Maiella platform margin record two episodes of platform drowning followed by hemipelagic sedimentation, dated as latest Oligocene–Aquitanian (26–23 Ma) and as Burdigalian–Langhian (20–16 Ma). A high-resolution stratigraphy, based on strontium- isotopes, allows us to correlate key phases of platform evolution with events recorded in deep water ocean sediments. This paper suggests that high weathering rates and nutrient input in the Mediterranean during the early and middle Miocene –possibly linked to the uplift of the Tibetan region – set the preconditions for platform drowning, which were ultimately caused by rapid eustatic sea-level rises.