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When a continental sized ice sheet first formed on Antarctica across the Eocene-Oligocene boundary the bed topography was significantly different to the modern day bed. As the bed evolved due to the effects of glacial erosion, sedimentation, subsidence and tectonics, it is hypothesised that the ice sheet sensitivity to climate forcing also changed. This hypothesis has been tested in a number of recent ice sheet modelling studies, but these efforts have been limited by the use of idealised bed topography estimates. Here we explore the ice sheet sensitivity to evolving bed topography using a recently produced suite of palaeotopographies for the Eocene-Oligocene and Oligocene-Miocene transitions, the mid-Miocene climatic optimum, and the late Miocene to early Pliocene. Al- though we present results for all of these intervals, we are particularly interested in whether bed topography played a role in Antarctic ice sheet stabilisation following the mid-Miocene climatic optimum and the final descent into the icehouse.
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Cenozoic Antarctic Peninsula Temperatures and Glacial Erosion Signals From a Multi‐Proxy Biomarker Study
Abstract Terrestrial climate records for Antarctica, beyond the age limit of ice cores, are restricted to the few unglaciated areas with exposed rock outcrops. Marine sediments on Antarctica's continental shelves contain records of past oceanic and terrestrial environments that can provide important insights into Antarctic climate evolution. The SHALDRIL II (Shallow Drilling on the Antarctic Continental Margin) expedition recovered sedimentary sequences from the eastern side of the Antarctic Peninsula of late Eocene, Oligocene, middle Miocene, and early Pliocene age that provides insights into Cenozoic Antarctic climate and ice sheet development. Here, we use biomarker data to assess atmospheric and oceanic temperatures and glacial reworking from the late Eocene to the early Pliocene. Analyses of hopanes andn‐alkanes indicate increased erosion of mature (thermally altered) soil biomarker components reworked by glacial erosion. Branched glycerol dialkyl glycerol tetraethers from soil bacteria suggest similar air temperatures of 12°C ± 1°C (1σ,n = 46) for months above freezing for Eocene, Oligocene, and Miocene timeslices but much colder (and likely shorter) periods of thaw during the Pliocene (5°C ± 1°C,n = 4) on the Antarctic Peninsula. TEX86‐based (Tetraether index of 86 carbons) sea surface temperature estimates indicate ocean cooling from 7°C ± 3°C (n = 10) in the Miocene to 3°C ± 1°C (n = 3) in the Pliocene, consistent with deep ocean cooling. Resulting temperature records provide useful constraints for ice sheet and climate model simulations seeking to improve understanding of ice sheet response under a range of climate conditions.
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- Award ID(s):
- 1908548
- PAR ID:
- 10372659
- Publisher / Repository:
- DOI PREFIX: 10.1029
- Date Published:
- Journal Name:
- Paleoceanography and Paleoclimatology
- Volume:
- 37
- Issue:
- 9
- ISSN:
- 2572-4517
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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