ENIGMAS OF THE NEOGENE STRATIGRAPHY OF THE EASTERN ROSS SEA, ANTARCTICA

The focus of this investigation is to examine the direct record of ice sheet expansion and contraction on the continental margin of the eastern Ross Sea, Antarctica, during the Neogene via seismic stratigraphy. The Ross Sea received 25% of ice sheet drainage from both the West Antarctic Ice Sheet (WAIS) and the East Antarctic Ice Sheet (EAIS) from the Oligocene through the Pleistocene and, therefore, this study also addresses questions concerning the dynamics of the two Antarctic ice sheets and linkages between the paleoclimate record and its impact upon sedimentation. Throughout the Pliocene-Pleistocene, the eastern basin of the Ross Sea was characterized by high rates of subsidence which created the accommodation required to preserve the Pliocene-Pleistocene sedimentary record of ice sheet fluctuations. Single-channel (SCS) and multi-channel (MCS) seismic data collected during four cruises in the Ross Sea in 1990, 1993, 1994, and 1996, create a dense dataset of over 20,000 km of data. Observations from the seismic data and correlation of the strata to Deep Sea Drilling Project (DSDP) sites in the Ross Sea provide a glacial sequence stratigraphic framework. This framework reveals that the transition from Miocene strata to the overlying Pliocene and Pleistocene strata does not reveal dramatic changes in seismic facies or stratal geometries. This suggests that either the Pliocene warming event had little impact upon the volume of the Antarctic ice sheets or that the volume change in the ice sheets was not of the magnitude required to modify depositional processes and therefore the stratigraphy that can be imaged in intermediate resolution seismic data.