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![-[A] Map of the 2005 SMS seismic survey lines and location of the SMS Project AND-2A site. The light black lines indicate existing marine seismic data (PD-90-46, PD-90-01/02, and IT-91-70), and the red lines show the location of the 2005 Southern McMurdo Sound (SMS) seismic survey lines collected from the ANDRILL Thunder Sled (ATS-05-01 and ATS-05-02). Existing stratigraphic drill holes are labeled MSSTS-1, CIROS-1. Dashed blue line shows the approximate extent of the 2005 ice breakout. (Figure after Speece et al., 2009).](profile/Florindo-Fabio/publication/216826925/figure/fig1/AS:394017561956354@1470952515228/A-Map-of-the-2005-SMS-seismic-survey-lines-and-location-of-the-SMS-Project-AND-2A.png)
-[A] Map of the 2005 SMS seismic survey lines and location of the SMS Project AND-2A site. The light black lines indicate existing marine seismic data (PD-90-46, PD-90-01/02, and IT-91-70), and the red lines show the location of the 2005 Southern McMurdo Sound (SMS) seismic survey lines collected from the ANDRILL Thunder Sled (ATS-05-01 and ATS-05-02). Existing stratigraphic drill holes are labeled MSSTS-1, CIROS-1. Dashed blue line shows the approximate extent of the 2005 ice breakout. (Figure after Speece et al., 2009).
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![Fig. 7 -[A] Map of the 2005 SMS seismic survey lines and location of...](profile/Florindo-Fabio/publication/216826925/figure/fig1/AS:394017561956354@1470952515228/A-Map-of-the-2005-SMS-seismic-survey-lines-and-location-of-the-SMS-Project-AND-2A_Q320.jpg)
During the austral spring of 2007, the Southern McMurdo (SMS) Project recovered a 1138.54 meter long drill core (AND-2A) from a 8.5 m thick floating seaice platform (~8.5 meters thick) over approximately 380 meters of water (77°45.488S; 165°16.613E) (Fig. 1). This demonstrated the ANDRILL Program’s continuing success in recovering high quality mari...
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... Inset (B) shows the regional tectonic setting (from Naish et al., 2007). (Barrett 1986;1989) and models for the evolution of the VLB ( Cooper et al., 1987;Fielding et al., 2006). F. Florindo et al. SMS Project were initially identified on seismic lines PD90-46 and PD90- 01/02 ( Fig. 7) obtained from R/V Polar Duke during the austral summer of 1990 ( Anderson and Bartek, 1992;Bartek et al., 1996). 'Local' seismic units were defined and reported in Harwood et al. (2005). These units were constrained by a series of surfaces that were traced using truncations/nonparallel geometry in relation to other reflectors, such as ...
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... SMS Project intended to recover a stratigraphic section that included a substantial portion of lower to upper Miocene strata. These target strata were identified along seismic line PD-90-46 and mapped into the SMS drillsite along lines ATS-05-01 and ATS-05-02 (Figs. 7, 8, and 9; Betterley et al., 2007) and comprise a multiple sequence of clinoform reflectors, which define stratigraphic units that expand basinward. These units lie stratigraphically above a regional erosion surface (seismic reflector "a" see Harwood et al., 2005; = beige of Fielding et al., 2008) that truncates the upper Eocene to lower ...
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... (SMS-X'). Following collection of additional sesimic data ( Betterley et al., 2007;Speece et al., 2009) and the recognition that the available drilling time window, which was restricted due to sea-ice breakout, prohibited two the drilling of sites in one season, a primary target for the SMS Project was identified on ATS-05-02 at shot point 597 (Figs. 7, 9). It was determined that this site would allow recovery of lower and middle Miocene strata and provide overlap with the AND-1B drillcore ( Naish et al., 2007) in the younger section, and with the composite CRP and CIROS-1 drillcore sequences of late Eocene to early Miocene age, in the lower section. Figure 10 presents a pre-drilling ...
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... Unit 5 is the youngest unit mapped from PD 90-46 into the ATS lines (Figs. 7, 9). This unit included the stratigraphic section above the "h" (dark green) reflector and below the "b-clino" (red) reflector of Fielding et al. (2008). The unit comprises strong reflectors that were inferred to indicate interbedded diamictite and fine-grained sediment of probable Late Miocene to Pliocene ...
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The palaeontological yield of the 1138.54 metre-long AND-2A sedimentary rock core provides unique documentation of Neogene environments in the Ross Sea region of Antarctica. Especially important is the biological legacy of the climatically crucial 'mild' middle Miocene phase. Diatom-bearing units provide key information for stratigraphie intervals...
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... The truncated top also formed by glacial erosion, mainly during the middle Miocene Climatic Transition (MMCT) and Pleistocene glaciations (Fielding, 2018). Younger sediments spanning the middle Miocene through to the Quaternary, although removed at the CIROS-1 site, are preserved at offshore sites south-east of CIROS-1 in cores AND-2A and AND-1B recovered by the Antarctic Drilling Program ( Fig. 1; Naish et al., 2007;Harwood et al., 2008). ...
Inorganic aragonite occurs in a wide spectrum of depositional environments and its precipitation is controlled by complex physio‐chemical factors. This study investigates diagenetic conditions that led to aragonite cement precipitation in Cenozoic glaciomarine deposits of McMurdo Sound, Antarctica. A total of 42 sandstones that host intergranular cement were collected from the CIROS‐1 core, located proximal to the terminus of Ferrar Glacier. Standard petrography, Raman spectroscopy and electron microprobe analysis reveal a prominent aragonite cement phase that occurs as a pore‐filling blocky fabric throughout the core. Oxygen isotope compositions (δ18O = –30·0 to –8·6‰ Vienna Pee‐Dee Belemnite) and clumped isotope temperatures (TΔ47 = 13·1 to 31·5°C) determined from the aragonite cements provide precise constraints on isotopic compositions (δ18Ow) of the parent fluid, which mostly range from –10·8 to –7·2‰ Vienna Standard Mean Ocean Water. The fluid δ18Ow values are consistent with those of pore water, previously identified as cryogenic brine in the nearby AND‐2A core. Petrographic and geochemical data suggest that aragonite cement in the CIROS‐1 core precipitated from a similar brine. The brine likely formed and infiltrated sediments in flooded glacial valleys along the western margin of McMurdo Sound during the middle Miocene Climatic Transition, and subsequently flowed basinward in the subsurface. Consequently, the brine forms as a longstanding subsurface fluid that has saturated Cenozoic sediments below southern McMurdo Sound since at least the middle Miocene. Aragonite cementation in the CIROS‐1 core is interpreted to reflect its proximal position to sites of brine formation and greater likelihood of experiencing brines with sustained high carbonate saturation states and Mg/Ca ratios. This unusual occurrence expands the range of known natural occurrences of aragonite cement. Given the potential for cryogenic brine formation in glaciomarine settings, blocky aragonite, as the end member of the spectrum of aragonite cement morphology, may be more widespread in glaciomarine sediments than currently thought.
... Horgan et al., 2005) beneath the McMurdo Ice Shelf during the first drilling season, whereas the AND-2A borehole was drilled into the flat lying sediments of South McMurdo Sound the following year. The ANDRILL sediment cores currently remain the longest and most complete records of Antarctic glaciation from the continental shelf with total lengths of ca 1285 m and ca 1138 m (Harwood et al., 2008), respectively. The AND-1B core was originally described by Krissek et al. (2007) at the Crary Science and Engineering Centre in McMurdo Station and later refined and interpreted by McKay et al. (2009). ...
The Upper Miocene interval of the AND‐1B sediment core is a muddy ca 300 m thick succession of glacimarine strata that was recovered from the McMurdo sector of the Ross Ice Shelf, Antarctica. This succession comprises lithofacies consistent with those formed in modern polythermal glacial systems with large volumes of subglacial meltwater. In particular, meltwater‐associated facies and iceberg‐rafted debris suggest that these late Miocene glacial systems were similar to subpolar glaciers like those in Svalbard today. Modern subpolar systems in Svalbard accumulate sediments at rates of ca 50 to 100 mm a−1 within ca 1 km of their grounded tidewater cliffs in waters up to hundreds of metres deep. Here, the rifted tectonic setting and glacio‐isostatic load of the Antarctic Ice Sheet enhanced accommodation for this succession. Based on these interpretations, the glacial sequence stratigraphic model of Powell & Cooper (2002) is applied to the study interval in an effort to better understand ice dynamics during this time. Base level is defined as the grounding‐line (where the ice sheet is grounded on the sea floor) and the surface that projects basinward – a correlative conformity. Glacial sequence stratigraphic description of the sediment core reveals 10 glacial sequences bounded by glacial erosion surfaces and two lower‐ranked glacial sequences bounded by correlative conformities. These glacial sequences occur in regular fining‐upward stratigraphic patterns and consist of two distinct styles of glacial retreat: packages with grounding‐line fan deposits and those without them. Lastly, in an effort to fill the gap between the middle Miocene and Plio‐Pleistocene climate histories of Antarctica, comparison of the AND‐1B Upper Miocene interval with the obliquity curve reveals one glacial‐interglacial cycle and identifies erosion surfaces along which significant time may be missing. This article is protected by copyright. All rights reserved.
... The local provenance near the base of the unit sug- gests TAM glaciers extended to this part of the Ross Sea. The deltaic sedi- ments inferred in CS2 were probably not deposited in large, shelf-break trough mouth fans as described by Vorren and Laberg (1997), as seismic lines near the drill site show no evidence for a shelf break or large, shelf troughs or incisions ( Florindo et al., 2008). Seismic resolution at this level is not sufficiently good to resolve these three cycles or any downlap seismic architecture as would be expected from delta progradation. ...
The lowest 501 m (~1139-638 m) of the AND-2A core from southern Mc- Murdo Sound is the most detailed and complete record of early Miocene sediments in Antarctica and indicates substantial variability in Antarctic ice sheet activity during early Miocene time. There are two main pulses of diamictite accumulation recorded in the core, and three significant intervals with almost no coarse clasts. Each diamictite package comprises several sequences consistent with ice advance-retreat episodes. The oldest phase of diamictite deposition, Composite Sequence 1 (CS1), has evidence for grounded ice at the drill site and has been dated around 20.2-20.1 Ma. It likely coincides with cooling associated with isotope event Mi1aa. This is overlain by a diamictite-free, sandstone-dominated interval, CS2 that includes three coarsening-upward deltaic cycles, is inferred to mark substantial warming, and has an inferred age range between 20.1 and 20.05 Ma. Above this is an interval with variable amounts of diamictite (CS3), with indicators of ice grounding, that is inferred to record ice advance relative to CS2, and is overlain by an ~100-m-thick mud-rich interval (CS4) with no sedimentological evidence for direct glacial influence at the drill site (ca. 19.4-18.7 Ma). A third overlying diamictite-rich interval (CS5) overlies an unconformity spanning 18.7-17.8 Ma (coinciding with isotope event Mi1b), and records a return to more ice-influenced conditions at the drill site in late early Miocene time. The overall picture for the early Miocene (spanning the period 20.2-17.35 Ma) is one of ice advance alternating with periods of ice retreat and hence significant global climate fluctuations after the permanent establishment of the Antarctic ice sheet at the Eocene/Oligocene boundary, and preceding the relative warmth of the middle Miocene climatic optimum (ca. 17.5-14.5 Ma). Sedimentary cyclicity in CS1 and CS2 is consistent with ~21 k.y. precession but in CS3 the frequency is closer to 100 k.y. (consistent with eccentricity), with a possible change to 20 k.y. precession in CS4. CS5 cyclicity is consistent with obliquity forcing. Provenance data are consistent with local Transantarctic Mountains glacial activity under precessional control in CS1 and more southerly ice-cap build up under 100 k.y. eccentricity and obliquity control during CS3 and CS5, respectively.
... List of cored boreholes utilized in this study, with their salient characteristics. Location of boreholes is given in Fig. 1 Harwood et al. (2008) achievement, but still short of pre-Eocene basement. ...
... In the VLB, strata of Quaternary age were recovered from AND-1B, AND-2A, CRP-1, CRP-2/2A, MSSTS-1 and CIROS-2 (Figs 12 to 15 and 18;Naish et al., 2007;Harwood et al., 2008;Cape Roberts Science Team, 1998Barrett, 1986;Barrett & Hambrey, 1992). Onshore, a variety of DVDP and ETV cores have recovered thicknesses of Quaternary strata, and surface exposures have also been informative (Figs 2, 6 and 17;Vucetich & Robinson, 1978;McGinnis, 1981;Robinson, 1983;Robinson & Jaegers, 1984;Fielding et al., 2012b). ...
The Victoria Land Basin forms part of the failed West Antarctic Rift, and preserves a Cenozoic succession up to 4 km thick that records the onset of Cenozoic glaciation, and the history of Antarctic glaciation over the past 34 Myr. This succession is relevant, both to investigations of modern climate change and to studies of long-term palaeoclimate change in general. This paper provides a sedimentological and stratigraphic review of the Victoria Land Basin succession, based on analysis of several continuous drillcores acquired since the 1970s, and supported by seismic stratigraphic analysis of a large array of seismic reflection data. An array of fifteen lithofacies is recognized within the Victoria Land Basin Cenozoic succession, including fossiliferous and diversely bioturbated mudrocks and diatomites, texturally mature sandstones and conglomerates, mixed mudstones and sandstones with dispersed gravel with restricted bioturbation, and diamictites and associated lithologies. These facies record a variety of marine, glaciomarine, proglacial and subglacial environments. Locally, volcanic and volcaniclastic deposits are interbedded in the succession. Lithofacies are arranged in repetitive vertical stacking patterns (depositional sequences) that record glacial advance–retreat cycles with attendant relative sea-level changes. Seven varieties of depositional sequences (stratigraphic motifs) are recognized within the succession as a whole, and interpreted to record a range of depositional settings from rifts unaffected by glacial ice (Motif 7), through varying degrees of glacial influence with abundant meltwater contributions (Motifs 6 to 3), to cold, polar glaciated environments such as that of today (Motifs 2 and 1). Overall, there is a gradual trend upward through the succession from Motif 7 at the base towards Motif 1 at the top, but the trend is not monotonic. A significant conclusion of this work is that a record of dynamic climate and glacial conditions is preserved through the entire 34 Myr period of the Cenozoic icehouse, at least in the Victoria Land Basin. Intervals characterised by consistent stratigraphic style (motifs) are recognised throughout the Victoria Land Basin succession. These intervals are of 1 to 6 Myr duration, each containing numerous depositional sequences; they are one to two orders of magnitude longer than glacial–interglacial cycles, and record periods during which environmental conditions varied in an internally consistent manner. These intervals are considered to reflect convolutions of orbital parameters that remained stable for periods of 10⁶ a, and then switched to alternative configurations. Such intervals are directly analogous to 1 to 8 Myr intervals characterised by glaciogenic strata that are preserved within the Late Palaeozoic of eastern Australia among other areas, and may be a recurring stratigraphic response to icehouse climate regimes through geological time.
... the Dry Valley Drilling Project (McGinnis, 1981), CIROS-1 and 2 (Barrett 1989;Barrett and Hambrey 1992), Cape Roberts Project (Cape Roberts Project Science Team, 1998, 1999, and the ANDRILL Program (Naish et al., 2007;Harwood et al., 2008). ...
The controls on reservoir quality of most clastic sedimentary deposits are well-documented and understood. However, comparatively little is known about the reservoir potential of glaciogenic and glaciomarine deposits. This study investigates the Neogene strata of the AND-2A core recovered by the ANDRILL-Southern McMurdo Sound Project in the Victoria Land Basin, Antarctica, as an analog for assessing controls on reservoir quality in glaciomarine deposits. A petrographic analysis was conducted on 60 sandstone samples from various depths throughout the core, and carbonate diagenetic phases and morphologies were documented. Four sequences were examined in detail. Point counting on all samples was done to determine percentages of cement, porosity, detrital mud, and framework grains. Results show that reservoir quality in glaciomarine sandstone is dramatically affected by the presence of diagenetic carbonate and strong correlations exist between carbonate cement abundance, paleoclimate, and sequence stratigraphic systems tract. Sandstones that formed during the coldest (polar and subpolar) climate regimes have relatively low porosities (
Decreased input of fine-grained sediments during colder climate regimes resulted in higher permeability deposits that were prone to infiltration by brine upon burial. By contrast, many texturally mature sandstones deposited in highstand deltaic settings during more temperate climate regimes preserve higher porosities (25 – 45%) and lack significant cementation. Sequence stratigraphic relationships indicate that these porous sandstones are best developed in highstand delta systems that formed during ice minima, when substantial volumes of meltwater were released from glacier termini. Individual sandstone bodies, which likely extend laterally over several kms, tend to be enclosed by muddy lithologies. Porosity in these sandstones was retained due to discharge of dilute meltwater during deposition and subsequent isolation of sands between impermeable barriers. Patterns identified in this study may prove useful in predicting and locating target reservoirs in other glaciogenic and glaciomarine settings worldwide.
Advisors: Tracy D. Frank and Christopher R. Fielding
... In recent years, our understanding of the Antarctic ice sheet history in southern Victoria Land has been significantly improved through the study of sediments recovered by drill cores offshore (Barrett et al. 2000;Hambrey and Barrett 1993;Fielding and Thomson 1999;Naish et al. 2007;Harwood et al. 2008). In 2007, the ANtarctic geological DRILLing program (ANDRILL) recovered sediments from 1,138.54 m of drill core in the AND-2A drill hole (Southern McMurdo Sound-SMS; Florindo et al. 2008; Fig. 1), which includes an exceptionally well-recovered late Early Miocene section dated 20. 2-16.7 Ma. This paper focuses on the Early Miocene heavy mineral assemblages in the ANDRILL AND-2A drill core, which was recovered near the terminus of a present-day glacier discharging through the Transantarctic Mountains. ...
The present study deals with heavy mineral analysis of late Early Miocene marine sediments recovered in the McMurdo Sound region (Ross Sea, Antarctica) during the ANDRILL— SMS Project in 2007. The main objective is to investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas. These data contribute to a better understanding of East Antarctica ice dynamics in the Ross Sea sector during the Early Miocene (17.6–20.2 Ma), a time of long-term global warming and sea level rise. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected a variety of terrigenous lithologies. The heavy mineral assemblages of the lower 650-m-thick sedimentary succession were analyzed through SEM observations and SEM–EDS microanalyses on heavy mineral grains. The heavy mineral analysis shows that the sediments are a mix of detritus dominated by McMurdo Volcanic Group sources most likely located in the present-day Mount Morning area (Proto-Mount Morning) with minor contribution from Transantarctic Mountains source rocks located west of the drill site. The heavy mineral assemblages in Interval 1 indicate
that between 20.2 and 20.1 Ma, the grounding line of the ice sheet advanced to a position near the present-day Mount Morning volcanic center. During deposition of Interval 2 (20.1–19.3 Ma), the ice sheet most likely experienced a dynamic behavior with interval of ice advance alternating with periods of ice retreat,
while Interval 3 (19.3–18.7 Ma) records further retreat to open water conditions. A dynamic behavior is noted in Interval 4 (18.7–17.6 Ma) with a decreasing contribution of materials derived from the basalts of the Mount Morning volcanic center located to the south of the drill site and a consequent increasing contribution of materials derived from the Transantarctic Mountains to the west of the drill site.
... AND-1B, drilled in 2006AND-1B, drilled in -2007AND-1B, drilled in to 1284.87 mbsf, recovered an expanded section recording the interval 13-0 Ma from the deep-water flexural moat adjacent to Ross Island ( Figure 1, Naish et al. 2007Naish et al. , 2009McKay et al. 2009). AND-2A, drilled in late 2007, recovered a core to 1138.54 mbsf, recording the time interval from 20-0 Ma, comprising an expanded succession from 20-14 Ma and a more fragmented record from 14 Ma onward (Harwood et al. 2008). Both projects achieved 98% core recovery over their total depth. ...
... During the drilling of at least two cored holes (CRP-2A and AND-2A: Cape Roberts Science Team 1999;Harwood et al. 2008), penetration of clean, porous sand beds led to significant loss of drilling fluid circulation, sand production into the well bore, and influx of large volumes of low-temperature groundwater. Downhole logging operations indicated increased porosity through an unconsolidated sand at 143-155 mbsf in CRP-2A (Cape Roberts Science Team 1999). ...
... This may in large part be due to the low subsurface temperatures in the region facilitated by active flow of cold groundwater, despite the magmatically active rift context of the VLB (Esser et al. 2004). Recorded bottomhole temperatures of 24.0 °C at 672 mbsf in CIROS-1, 17.2 °C at 624 mbsf in CRP-2A, 23.0 °C at 870 mbsf in CRP-3 and 56.9 °C at 1138 mbsf in AND-2A (Barrett 1989;Cape Roberts Science Team 1999Harwood et al. 2008) suggest that low temperatures are mainly responsible for slowing rates of diagenetic modification in the subsurface. Downhole logging operations in these holes indicated evidence of significant (cold) fluid flow where the typically unconsolidated, permeable sand horizons were encountered (Cape Roberts Science Team 1999Harwood et al. 2008). ...
This paper provides documentation of unexpectedly high-reservoir-quality glaciomarine sands found in the Cenozoic succession beneath McMurdo Sound, Antarctica, as an analogue study for evaluations of hydrocarbon prospectivity in basins elsewhere. The Oligocene to Lower Miocene succession of the Victoria Land Basin, an extant portion of the West Antarctic Rift System, comprises diamictites, mudrocks, and sandstones with minor conglomerates. These lithologies are arranged in repetitive stacking patterns (cycles), interpreted to record repeated advance and retreat of glaciers into and out of the basin, with attendant eustatic and isostatic effects. Phases of ice retreat within the cycles comprise an array of mudrocks, sandy mudrocks, and sandstones, deposited mainly during relative sea-level highstands. Clean, wellsorted, unconsolidated, and porous sands <25 m thick from such intervals, which are interpreted to be mainly deltaic in origin, were encountered. Some of these sands, which have visible porosity as high as 41%, flowed into the well bore together with significant volumes of cold formation water. Diagenetic modification of sands in these intervals is minimal, which can be attributed to the low-temperature nature of the subsurface environment. Accordingly, glaciomarine sands in near-field glaciogenic successions should be considered as potential reservoir facies in prospectivity assessments.
... A facies analysis and preliminary stratigraphic analysis of the AND-2A core is documented in Harwood et al. (2008), and a more detailed treatment of lithofacies and interpreted environments of deposition, proximity of glacial ice to the drillsite, and glacial thermal regime is given by Passchier et al. (in press). In the present paper, we build on this framework and describe a sequence stratigraphic analysis of the core drawing on existing stratigraphic models derived from the VLB succession. ...
Present understanding of Antarctic climate change during the Early to Mid-Miocene, including major cycles of glacial expansion and contraction, relies in large part on stable isotope proxies from deep sea core drilling. Here, we summarize the lithostratigraphy of the ANDRILL Southern McMurdo Sound Project drillcore AND-2A. This core offers a hitherto unavailable ice-proximal stratigraphic archive from a high-accommodation continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/contraction and attendant sea-level change over the period c. 20.2–14.2Ma, with a more fragmentary record of Late Miocene and Pliocene time. The core is divided into seventy-four high-frequency (fourth- or fifth-order) glacimarine sequences recording repeated advances and retreats of glaciers into and out of the Victoria Land Basin. The section can be resolved into thirteen longer-term, composite (third-order) sequences, which comprise packages of higher frequency sequences that show a consistent stratigraphic stacking pattern (Stratigraphic Motif). The distribution of the six recognized motifs indicates intervals of less and more ice-proximal, and temperate to subpolar/polar climate, through the Miocene period. The core demonstrates a dynamic climate regime throughout the Early to Mid-Miocene that may be correlated to some previously-recognized events such as the Mid-Miocene Climatic Optimum, and provides a detailed reference point from which to evaluate stable isotope proxy records from the deep-sea.
... The Antarctic Geological Drilling (ANDRILL) program is an ongoing multinational collaborative effort to drill Antarctica's margin (Florindo et al., 2008). shallow units (e.g., LSU 2, 37.1 to 98.5 m), and recrystallization is observed above and below LSU 7 (e.g., LSU 5 -6, 122.9 to 339.9 m, and 10 -12, 648.7 to 996.7 m). ...
Oxygen and strontium from biogenic carbonates (mostly bivalves) were used to evaluate paleoenvironmental interpretations on the basis of modern analogs along the North American east coast and to offer chronostratigraphic, paleoenvironmental, and diagenetic constraints to Neogene sequences from Southern McMurdo Sound, Antarctica. These are relevant pursuits in light of imminent climatic changes, which heighten the need for reliable paleoenvironmental interpretations and for data from climate???sensitive regions. In Vineyard Sound, Massachusetts, U.S.A., d18O from several coexisting shallow marine taxa and well???constrained environmental parameters were used to test the extent to which the known local annual variation of these parameters was represented in the shell carbonate. This relation was explored through the construction of time series from bivalve d18O versus shell distance profiles and the calculation of growth rates and isotopic fractionation factors. It was discovered that the marine temperature range recorded in the biogenic carbonate extended to lower temperatures than expected and was, in its entirety, better represented not by a single taxon but by the concurrent use of multiple taxa. Modeling of bivalve d18O of modern shallow marine environments along the North American east coast showed that large salinity ranges complicate environmental interpretations. However, modeled clams showed that d18O seasonal variability can discriminate between tropical and temperate shallow water marine climates. Higher variability characterizes the winter of tropical zones while the opposite is true for temperate regions. 87Sr/86Sr and Sr concentration of unaltered calcite bivalves from ANDRILL???s core AND???2A produced reliable ages and confirm contrasting marine climate conditions across the Middle Miocene of Southern McMurdo Sound, Antarctica. In contrast, seemingly unaltered aragonite shells invariably produced older than expected ages. Additional analyses of the aragonite shells and 87Sr/86Sr compositions of pore water were carried out to reconcile these results. d18O and Sr concentrations of pore water and aragonites suggested that the anomalous ages are likely the result of early diagenetic alteration, even in the absence of mineralogical change.
... These include the Dry Valley Drilling Project (DVDP) in 1970-1975(McGinnis, 1981, the McMurdo Sound Sediment and Tectonic Studies (MSSTS) in 1979 (Barrett, 1986), the Cenozoic Investigations in the Western Ross Sea (CIROS) in 1984 and 1986 (Barrett, 1989;) and the multinational CRP in 1997-1999(Cape Roberts Science Team, 1998, 1999, 2000Hambrey et al., 1998;Barrett et al., 2000Barrett et al., , 2001. These efforts are continuing through ANDRILL (Antarctic geological drilling) programme, which demonstrated ability to recover high quality marine and glacimarine sedimentary drill cores from high latitude ice-covered areas (Naish et al., 2007;Florindo et al., 2008;Harwood et al., 2008). ...
This chapter explores the Middle Miocene to Pliocene terrestrial and marine records of Antarctica and the Southern Ocean. The structure of the chapter makes a clear distinction between terrestrial and marine records as well as proximal (on or around Antarctica) and more distal records (Southern Ocean). Particular geographical regions are identified that reflect the areas for which the majority of palaeoenvironmental and palaeoclimatic information exist. Specifically, the chapter addresses the terrestrial sedimentary and fjordal environments of the Transantarctic Mountains and Lambert Glacier region, the terrestrial fossil record of Antarctic climate, terrestrial environments of West Antarctica, and the marine records of the East Antarctic Ice Sheet (EAIS), the West Antarctic Ice Sheet (WAIS) and the Antarctic Peninsula Ice Sheet (APIS), as well as the marine record of the Southern Ocean. Previous and current studies focusing on modelling Middle Miocene to Pliocene climate, environments and ice sheets are discussed.
