Abstract:
The Wilkes Land sector of the East Antarctic Ice Sheet is hypothesized to have varied significantly in volume during the early Pliocene warm period. Here, we present a cyclostratigraphy for the Plio-Pleistocene interval of the Integrated Ocean Drilling Program (IODP) Site U1361, located on the Wilkes Land margin, to investigate the potential sensitivity of this ice sheet to warmer-than-present climates and orbital forcing. Using sedimentology and physical proper ties logs, we investigate cyclic variability in sedimentary deposition operating at Milankovitch frequencies to interpret relationships between ice sheet dynamics, sea ice variability, and oceanographic changes at the EAIS margin. We present a high-resolution grain size record of the Pliocene to early Pleistocene (4.4 to 1.8 Ma) in U1361. Periodic oscillations in the grain size, and physical proper ties logs accurately represent distinct lithofacies and have enabled a high resolution cyclostratigraphy to be developed. Using paleomagnetic reversals as age contrain tie points, cyclic variations in physical proper ties and ice-rafted debris can be visually correlated to the benthic oxygen isotope record of global ice volume throughout the Plio-Pleistocene. We then conduct spectral analysis on the physical proper ties to test the statistical significance of orbital controls on cyclic sedimentation occurring at the Wilkes Land margin during the late Neogene.