Are Antarctic Peninsula Ice Sheet grounding events manifest in sedimentary cycles on the adjacent continental rise? |
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| Institution: | 1. Dipartimento di Scienze della Terra e del Mare (DiSTeM), Università di Palermo, Via Archirafi 36, 90123 Palermo, Italy;2. Microbiogeochemistry, Institute for Chemistry and Biology of the Marine Environment, Carl-von-Ossietzky University, Oldenburg, Germany;3. Geosciences Division, Alfred Wegener Institute for Polar and Marine Research, Bremerhaven, Germany;1. Geology Department, Colgate University, Hamilton, NY, USA;2. School of Earth and Ocean Sciences, Cardiff University, Cardiff, Wales, UK;3. Department of Environmental Earth Systems Science, Stanford University, Stanford, CA, USA;1. CAS Key Laboratory of Mineralogy and Metallogeny/Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, 511 Kehua Street, Guangzhou 510640, China;2. University of Chinese Academy of Sciences, 19 Yuquan Road, Beijing 100049, China;1. Department of Geology, University of Otago, P O Box 56, Dunedin 9054, New Zealand;2. School of Environment, University of Auckland, Private Bag 92019, Auckland 1142, New Zealand;3. GNS Science, P O Box 30-368, Lower Hutt 5040, New Zealand |
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| Abstract: | The direct record of Late Miocene–Early Pliocene Antarctic Peninsula Ice Sheet expansions from a previously published seismostratigraphic study of the outer shelf at Ocean Drilling Program Site 1097 is compared to the glacial history we deduced from published proxy evidence within coeval sections on the adjacent continental rise. The proxies are sedimentary structures (laminated vs. massive/bioturbated facies) and clay minerals (predominantly smectite and chlorite contents) from Ocean Drilling Program Site 1095 located on the distal part of a large drift. The comparison shows that more sedimentary cycles are evident on the continental rise for three of the four diatom biozones we considered. This indicates that the continental-rise sedimentology may indeed be related to local or regional paleoenvironmental variability, including Antarctic Peninsula Ice Sheet grounding events on the adjacent outer continental shelf. If correct, this would be a promising result because unlike the outer continental shelf sequences drilled thus far, the continental rise record is relatively continuous and can be dated using paleomagnetic and biostratigraphic data. However, our study also shows that no objective criteria provide direct linkages between the glacial history we deduced from the two continental rise proxies and that previously derived from the continental-shelf seismic stratigraphy. Furthermore, the two sedimentologic proxies on the continental rise do not always provide a consistent picture of glacial history when compared against each other. |
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