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Stratigraphic Lexicon: The Onshore Cenozoic Sedimentary Formations of The Republic of Panama
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The stratigraphic knowledge of Panama was, until now, spread over hundreds of scientific/geologic publications written during the past 120 years. The construction of the Panama Canal during the early twentieth century helped galvanizing the engineering and geological disciplines to understand the tectonic, sedimentation and biodiversity of the Cenozoic Era in this part of the world. Later, few petroleum companies arrived on the scene and contributed to our knowledge of the sub-surface. The past thirty years saw a surge of studies by many institutions in areas away from the Canal, such as in Darien, Azuero Peninsula, Bocas del Toro, and the Burica Peninsula near the Costa Rica Border. Our most recent knowledge came from the widening of the Panama Canal between 2007 and 2016. It is from all these older and recent studies that the present Lexicon draws its content. It provides the historical background of all described geological units in Panama and summarizes the lithological and paleontological knowledge of each units in an easy-to-search format.
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The current knowledge of the stratigraphy of Niger benefited greatly from the mining, hydrocarbon, hydrogeological, and paleontological sciences. Exploration by early explorers and studies of the aquifers initially sparked our understanding of the surface and shallow formations. Then, the discoveries in 1957 of important Uranium reserves and soon after in 1964 of the enormous Lower Cretaceous vertebrate site of Gadoufaoua stressed the need to undertake detailed stratigraphical investigations in the western Iullemmeden Basin. The geologist Hughes Faure then published his important, and still relevant, 1966 thesis on the surface geology of Eastern Niger. From that time onward, the Oil & Gas companies started paying attention to the most prospective areas in the Eastern Niger Basin. During the last decade, these same hydrocarbon companies finally allowed some geologists to share their knowledge of the sub-surface in relevant publications. It is from all these studies that the present Lexicon draws its content. It provides the historical background of all described geological units in Niger and summarizes each unit's lithological and paleontological knowledge in an easy-to-search format.
The Geology of Colombia book provides an updated background of the geological knowledge of Colombia by integrating the most up–to–date research covering paleontology, biostratigraphy, sedimentary basin analysis, sedimentology, sequence stratigraphy, stratigraphy, geophysics, geochronology, geochemistry, thermochronology, tectonics, structure, volcanology, petrology, environmental science, climate change, and space geodesy.
Each chapter has a complete framework of a major branch of geology providing an invaluable resource for geologists interested in the geological history of Colombia.
The third volume has seventeen chapters that present the best preserved record of Chicxulub impact deposits at the Cretaceous/Paleogene boundary on Gorgonilla Island; geologic evolution of the Tumaco Forearc, Amagá, the San Jacinto fold belt, the Middle and Lower Magdalena and Llanos Basins; uplift and structural styles of the Eastern Cordillera; fluvial–lacustrine and volcanic records of the Morales Formation; Cenozoic marine carbonate systems of Colombia; provenance in modern rivers draining the Eastern and Central Cordilleras, as well as different levels of exhumation across the Bucaramanga Fault in south–western Santander Massif; new information on the Chocó–Panamá Arc and the Isthmian bedrock geology; Miocene tholeiitic and calc–alkaline magmatism from the northern Andes; and Cenozoic geologic evolution of the Sierra Nevada de Santa Marta.
Silicified woods are abundant on the Azuero Peninsula in Panama, but only five publications document Oligocene-Miocene occurrences in the region. In this article, we present two new fossil wood types from the Azuero Peninsula. The first shares traits diagnostic of Prioria (Fabaceae) emended Breteler. Characters supporting this identification include alternate minute intervessel pitting, vessel-ray parenchyma pitting similar to intervessel pits in size and shape, axial canals that are diffuse and in short lines, and rays that are 1–3 cells wide. Prioria was also reported from the Miocene Cucaracha Formation in the area of the Panama Canal. The second one belongs to the Malvaceae, however, we cannot place it in any known fossil or extant genus. . We propose a new fossil genus, Veraguasoxylon, based on the occurrence of slight tangential arrangement of vessels, paratracheal axial vasicentric parenchyma, apotracheal axial diffuse parenchyma, rays that are 4–10 cells wide, and ´Pterospermum´ type tile cells.
These two new reports contribute to the diversity of plants known from Panama prior to the closure of the Central American Seaway. They also provide further evidence that Azuero hosted a diverse rainforest during the Oligocene-Miocene.
We provide a description of the remains of a fossil whale from western Panama. The record consists of appendicular remains of a mysticete, which has been assigned to Balaenopteridae. These remains, found in the sediments of the late Pliocene Burica Formation, represent the first record of a marine mammal in the Neogene sedimentary succession of the Burica Peninsula. Two different types of shark bite marks, serrated and deep-unserrated, found on the radius and phalanges suggest scavenging by at least two white shark (Carcharodon) individuals. The deep, unserrated marks were possibly caused by continual biting by sharks. Both the morphology of the shark bite marks and their relative location on the whale limb bones constitute evidence of shark-cetacean trophic interaction. Although the specimen lacks diagnostic features that would allow a species-level identification, it does provide new information on the vertebrate fauna of a very poorly prospected Central Eastern Pacific exposure, thus opening an opportunity for exploring the marine fauna during a critical episode in Earth history, the Plio-Pleistocene transition.
Formation of the Panama Isthmus, that had global oceanographic and biotic effects in the Neogene, is generally associated with tectonic uplift during collision of the Panama volcanic arc with South America. However, new field, geochemical and geochronological data from the Culebra Cut of the Panama Canal suggest that volcanism also contributed to the Isthmus emergence in the Early Miocene. This volcanism is recorded in a newly-recognised Central Panama volcanic field that includes several phases of development. Early activity of this field along the Panama Canal was associated with proximal effusive to explosive felsic products during formation of subaerial stratovolcanoes and possible domes ca. 21 Ma. This was followed by a period of marine transgression ca. 21–18 Ma, with more distal volcanism documented by tuffs that deposited in marine to terrestrial environments. Finally, proximal mafic volcanism formed tephra cones in a monogenetic field ca. 18(-?) Ma. This was associated with phreatomagmatic processes in a coastal environment, with remarkable kilometre-wide subvolcanic peperitic intrusions. We propose based on these observations that formation of the Central Panama volcanic field was critical in shaping regional topography, and that this could have actively contributed to obstruction and closure of an interoceanic strait in Central Panama.
During the last 20 years of paleontological expeditions in different sedimentary basins of Brazil, Colombia, Costa Rica, Ecuador, Jamaica, Trinidad, Panama, the Dominican Republic and Venezuela, teleost otoliths have been found along the tropical western central Atlantic (TWCA) and the tropical eastern central Pacific (TECP); these otoliths relate to the amphi-American distribution of fishes and the paleoceanographic and paleoenvironmental changes in the region during the Cenozoic. This study analyzes of the marine fish fossil based on comprehensive species records belonging to the Neogene period and listed at the generic level. Joint classification and ordi- nation techniques were used to identify and analyze data comprising 169 genera belonging to 56 families and 20 orders, which were mostly represented by the demersal species that inhabit shallow waters. Analyses of principal components were used to calculate the covariance and the variance between formations, countries, basins, and age. The results showed that the main faunistic changes along the geochronological sequence in the Neogene basins of tropical America were a consequence of paleoenvironmental changes.
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This paper describes the rise of eustatic sea level in the Gulf of Panama, Panama, and the formation of the Pearl Islands and Taboga archipelagos during the late Pleistocene and Holocene since the end of the last glacial maximum at about 21 ka. The sea level was then about 130 m below present and the Gulf was occupied by a wide grassy plain some 150 km long and 200 km wide, the Las Perlas drowned plain. A series of palaeogeographic maps, or time-slices, were made using bathymetric maps and published global sea-level curves. The first stage of sea level rise was rapid, by 125 m to -5 m in about 14,000 years from 21 ka to 7 ka. Since then the rate of change has been slow. There is geomorphological evidence from raised beaches and stranded shorelines that relative sea level actually rose to about +2 m in the mid Holocene high stand and since then has regressed to the present-day shore line: further work is required to date this and determine whether the cause was eustatic or tectonic.
The Pearl Islands became a single big island by the time sea level reached about -40 m between about 10.2 and 10.0 ka. Pedro Gonzalez Island and San José Island on the west side of the archipelago were separated from the other islands at about 8.8 to 8.3 ka. The remaining big island separated into smaller islands over the next 1,500 years by 7.5 to 7.2 ka. The Taboga archipelago became islands at about 9.4 to 9.0 ka. The main geomorphological and bathymetric effects of sea level rise include flooded valleys, submarine valleys and buried river valleys.
The wide grassy Las Perlas plain would have aided the first human migrations through the isthmus at 14.0 to 11.0 ka. The Gulf of Panama is inferred to have had a similar history of multiple regressions and transgressions related to fluctuating glacial and interglacial periods throughout the Pleistocene. The wide plains developed during sea level low-stands may also have been an important factor in the Great American Biotic Interchange at the start of the Quaternary.
Understanding evolutionary transitions in scleractinian corals is fundamental to predicting responses of coral reefs to climate change. We examine transitions between solitary and colonial corals in the fossil record, focusing on the Caribbean solitary reef coral Scolymia and members of the subfamily Mussinae. Fossil specimens are selected from a large well-documented collection of Neogene Caribbean corals, and a total of 23 species are distinguished using 15 morphological features. Ten of the 23 species are extant Caribbean species, seven are previously described extinct Neogene species, and six other extinct species are formally described as new. The 7 + 6 extinct species are added to a morphological data set consisting of 30 extant molecularly characterized species plus seven additional extinct (five Eocene, two Neogene) species. In addition to the Caribbean subfamily Mussinae, the extant species include the Indo-Pacific families Merulinidae and Lobophylliidae, and the Caribbean subfamily Faviinae. Phylogenetic analysis was performed on the data using maximum parsimony, and the results reveal four clades, which correspond with previously reported molecular clades. Solitary corals group most closely with Caribbean Mussinae and Indo-Pacific Lobophylliidae, whereas colonial corals are present in all four clades. Within Caribbean Mussinae, members of the colonial genera Mycetophyllia and Isophyllia form distinct subclades, as do the extinct solitary genera Antillia and Antillophyllia. The relationships within Scolymia are less well defined but its members appear more closely related to extinct solitary genera dating back to the Eocene. These results indicate that evolutionary transitions between solitary and colonial corals have been rare within the Mussinae. Except Antillophyllia, most Mussinae genera are restricted to the Caribbean. During the late Miocene, Mycetophyllia diversified and three other modern Mussinae genera (Mussa, Scolymia, Isophyllia) originated in association with increased Caribbean productivity. Mussinae that were more likely to survive Plio–Pleistocene extinction may have taken refuge in deep forereef habitats.