Cenozoic ice sheet history from east Antarctic Wilkes Land continental margin sediments.

• Published in: Global and Planetary Change
• Main Authors: Escutia, Carlota, De Santis, Laura, Donda, F., Dunbar, R.B., Cooper, A.K., Brancolini, G., Eittreim, S.L.
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2005
• Subjects: Wilkes Land; Cenozoic; East Antarctic Ice Sheet; Glacial evolution; Antarctic; Antarc*; Ice Sheet
• Online Access: http://hdl.handle.net/10261/18848; https://doi.org/10.1016/j.gloplacha.2004.09.010

10 figures, 3 tables. The long-term history of glaciation along the East Antarctic Wilkes Land margin, from the time of the first arrival of the ice sheet to the margin, through the significant periods of Cenozoic climate change is inferred using an integrated geophysical and geological approach. We postulate that the first arrival of the ice sheet to the Wilkes Land margin resulted in the development of a large unconformity (WL-U3) between 33.42 and 30 Ma during the early Oligocene cooling climate trend. Above WL-U3, substantial margin progradation takes place with early glacial strata (e.g., outwash deposits) deposited as low-angle prograding foresets by temperate glaciers. The change in geometry of the prograding wedge across unconformity WL-U8 is interpreted to represent the transition, at the end of the middle Miocene “climatic optimum” (14–10 Ma), from a subpolar regime with dynamic ice sheets (i.e., ice sheets come and go) to a regime with persistent but oscillatory ice sheets. The steep foresets above WL-U8 likely consist of ice proximal sediments (i.e., water-lain till and debris flows) deposited when grounded ice-sheets extended into the shelf. On the continental rise, shelf progradation above WL-U3 results in an up-section increase in the energy of the depositional environment (i.e., seismic facies indicative of more proximal turbidite and of bottom contour current deposition from the deposition of the lower WL-S5 sequence to WL-S7). Maximum rates of sediment delivery to the rise occur during the development of sequences WL-S6 and WL-S7, which we infer to be of middle Miocene age. During deposition of the two uppermost sequences, WL-S8 and WL-S9, there is a marked decrease in the sediment supply to the lower continental rise and a shift in the depocenters to more proximal areas of the margin. We believe WL-S8 records sedimentation during the final transition from a dynamic to a persistent but oscillatory ice sheet in this margin (14–10 Ma). Sequence WL-S9 forms under a polar regime during the ...