Evidence for Ice covered West Antarctica during late Pliocene/early Pleistocene transition
In Antarctic glaciology and climate change research, one of the most important questions is whether the West Antarctic Ice Sheet (WAIS) experienced complete or partial collapse during the late Pliocene to early Pleistocene period. This is essential because the possibility of WAIS collapse in the nea...
| Other Authors: | , , , |
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| Format: | Thesis |
| Language: | English |
| Published: |
2021
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| Subjects: | |
| Online Access: | https://digitalcollections.wesleyan.edu/objectir-3273 https://doi.org/10.14418/wes01.2.341 https://digitalcollections.wesleyan.edu/sites/default/files/2023-03/17153-Thumbnail%20Image.png |
| Summary: | In Antarctic glaciology and climate change research, one of the most important questions is whether the West Antarctic Ice Sheet (WAIS) experienced complete or partial collapse during the late Pliocene to early Pleistocene period. This is essential because the possibility of WAIS collapse in the near future, with a resulting rise in global sea level, is a major concern. The structure and stability of the ice sheet throughout past glacial/interglacial cycles, on the other hand, remain mystery, especially in the Southern Ocean owing to its lack of high-resolution data and age constraints. Here we present geochronological evidence and sediment record of ice-rafted debris (IRD) from the late Pliocene (2.65 Ma) to the early Pleistocene (1.75 Ma) to analyze the ice sheet evolution during this time. IODP Expedition 382 recovered a continuous stratigraphic record in the Dove Basin (Site 1537) providing the opportunity to explore Antarctic's glacial evolution and ice dynamics. In this study the 150 to 500¿m size fraction of IRD was investigated with well-dated high-resolution natural gamma ray (NGR) and gamma ray attenuation (GRA). Age dating was provided by shipboard and shore based paleomagnetic records. IRD mass accumulation rates (MAR) were generally low (2.43 g/cm2/kyr) in this time span. This research used 40Ar/39Ar dating of hornblende to determine IRD provenance and NGR to identify glacial/interglacial intervals. Three depositional units were defined by NGR and IRD MAR. In unit I (1.75-2.12 Ma), we observed five IRD peaks (MAR > 6g/cm2/kyr), three of which are associated with weak interglacial stage or glacial stage (relatively high NGR or GRA). One of the IRD maxima falls in the transitional period (interglacial to glacial) and another peak falls into the interglacial. In unit II (2.12-2.42 Ma) we discovered a very low IRD accumulation rate overall (mean 1.24 g/cm2/kyr) throughout the highest warming period. In unit III, we identified three IRD maxima. Two of them are related with the glacial period, ... |
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