Enviromagnetic and sedimentologic characteristics of sediments from inner Pine Island Bay (Amundsen Sea): implications for the paleoenvironmental and deglaciation history
The Amundsen Sea sector of the West Antacric Ice Sheet (WAIS) has shown significant changes over the last few decades and may rise global sea level by 1.5 m, if complete disintegration takes place in the future. Pine Island and Thwaites Glacier, which drain into the Pine Island Bay show accelerated...
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| Format: | Thesis |
| Language: | unknown |
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2013
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| Online Access: | https://epic.awi.de/id/eprint/35141/ https://hdl.handle.net/10013/epic.26e43319-8dd0-4afb-bbb9-8b4b9ae3591f |
| Summary: | The Amundsen Sea sector of the West Antacric Ice Sheet (WAIS) has shown significant changes over the last few decades and may rise global sea level by 1.5 m, if complete disintegration takes place in the future. Pine Island and Thwaites Glacier, which drain into the Pine Island Bay show accelerated ice flow, thinning and grounding line retreat. Herein the results of a combined ap- proach of magnetic and sedimentologcial methods on a sediment core from inner Pine Island Bay are presented. They aim to contribute to the understanding of past WAIS behaviour in the Pine Island Bay and help to improve future projections of ice retreat. A minimum deglaciation age of 9.4 ka BP was obtained by radiocarbon dating. Unfortunately tuning of RPI failed because the sediments was inadequate for this technique. Nevertheless a possible subglacial lake deposit is described which may hold significant informations about pre- Holocene sediment deposition in inner Pine Island Bay. The sequence also indicates a possible ice readvane in Pine Island Bay associated with the Antarctic Cold Reversal. The most prominent feature however, is a change in the sediment source with the onset of the Holocene documented by different clay and magnetic mineral assemblages. The high resolution of the magnetic measurements allowed to identify this change as rather sharp than indicated by the clay minerals. The pre-Holocene sediments at the core site are characterized by high percentages of hematite/goethite and coarse magnetite, whereas Holocene sediments are dominated by fine grained magnetite. Sedimentological, the early Holocene sequence in the core is characterized by meltwater flow de- posits with a gradual transition to hemipelagic sedimentation in the mid-late Holocene. A decrease in magnetic particle size shows phases of possible grounding line retreat during the Holocene. |
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