Seismic Record of Late Oligocene Through Miocene Glaciation on the Central and Eastern Continental Shelf of the Ross Sea

Seismic stratigraphic record of the Amundsen Sea Embayment shelf from pre-glacial to recent times: Evidence for a dynamic West Antarctic ice sheet

“…The best analogue for the ASE shelf appears to be the Eastern Basin of the Ross Sea shelf, because both regions share a similar continental breakup history and glacial sedimentation processes by the same ice sheet. Seismic profiles BGR80-07 and PD90-30 (Cooper et al, 1991;Anderson and Bartek, 1992;De Santis et al, 1995, 1999Brancolini et al, 1997;Anderson, 1999;Chow and Bart, 2003) cross DSDP Sites 270, 272 and 271 and show a striking similarity in the pattern and sequence of seismic units and unconformities with those of our transect AWI-20100132 to -0135 (Fig. 4b,c).…”

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“…Unconformity RSU3 (key target of proposed Site EBOCS-03C) provides the first evidence for a major cross-shelf paleotrough eroded by an expanded WAIS, although the age of this event(s) is poorly constrained (~14-4 Ma; Figures F6, F8) (Bart, 2003;De Santis et al, 1995. Large meltwater and outwash features are absent and laminated seismic facies are progressively thinner/less common in strata younger than Unconformity RSU3, suggesting sediment starvation and a transition to a colder glacial regime.…”

“…The ANTOSTRAT seismic stratigraphic scheme defines eight seismic units (RSS-1 to RSS-8) within the sediment infill lying above the basement, bounded by six major shelf-wide unconformities (RSU1 to RSU6) (Table T1; Figure F6) De Santis et al, 1995), but their ages are only partially constrained by drilling (see synthesis by Bart and De Santis, 2012). In the western Ross Sea, CIROS-1 and CRP-3 indicate marine-terminating glaciation in the TAM by the earliest Oligocene (Barrett, 2007(Barrett, , 1989.…”

Drilling and modeling studies expose Antarctica’s Miocene secrets

“…Although these paleothermometers are not yet calibrated adequately to assess absolute ocean temperatures at high latitudes (17,18), intervals of relative ocean warmth coincide with independent marine and terrestrial pollen, spore, and geomorphologic evidence for regional warmth, meltwater influx, and ice retreat into the Transantarctic Mountains between 16.4 and 15.8 Ma (1, 10, 16). Additionally, a series of three chronologically constrained missing and condensed sections in the AND-2A drill core mark the MCO onset and MMCT progression of ice advance across the Ross Sea continental shelf (15).…”

“…(1) reconstruct MCO glacial dynamism long-suspected from both near-field Antarctic terrestrial and continental shelf studies, and far-field ice volume and sea-level records (3, [8][9][10][13][14][15][16] interpretations. Ocean temperatures from two recently developed geochemical paleothermometers (17,18) are integrated with pollen and geochemical data to provide insight into the evolution of the regional environment.…”