2003 Seattle Annual Meeting (November 2–5, 2003)

Paper No. 1
Presentation Time: 1:30 PM-5:30 PM


RAMSEY, Heather N. and BARTEK, Louis R., Geological Sciences, Univ of North Carolina at Chapel Hill, CB 3315, Mitchell Hall, Chapel Hill, NC 27599, hnramsey@email.unc.edu

The Pliocene Epoch generates a lot of interest due to the fact that many types of data from around the world indicate that it was one of the most recent intervals of warmth since the late Mesozoic and early Paleogene, and thus is a useful analog for determining the nature of the impact that climate warming may have on oceanic circulation and the distribution of flora and fauna. Understanding the impact of warming on the stability of Antarctic ice sheets is a critical because the cooling of adjacent ocean waters drives formation of deep waters and vigorous oceanic circulation. The strata of the Ross Sea, Antarctica, are the focus here because they received 25% of ice sheet drainage from both the West and East Antarctic ice sheets from the Oligocene through the Pleistocene and therefore are a good barometer of ice volume change. Miocene units in the Ross Sea consist of offlapping reflections in dip-oriented profiles and broad cross-cutting troughs in strike-oriented profiles, which is consistent with Pleistocene subglacial strata in the Ross Sea. Application of sequence stratigraphic techniques to the overlying strata reveals 7 distinct sequences. Correlation of these strata to Deep Sea Drilling Project (DSDP) sites in the Ross Sea indicates that they are Plio-Pleistocene in age. The transition from the Miocene strata to the overlying strata does not reveal a dramatic change in seismic facies or stratal geometries. This suggests that: (1) the Pliocene warming event had little impact on the volume of the Antarctic ice sheets or (2) there was a significant volume change in the ice sheets, but the change did not cause a modification in depositional processes that was large enough to leave a dramatic change in the facies and stratigraphy that can be imaged in intermediate resolution (3-7 m) seismic data and the poorly sampled DSDP cores from the margin. Acquisition of shallow (50 m) drill core will resolve this issue.