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Antarctic Peninsula Climate Variability: APRIL 3-5, 2002 |
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Application of magnetic methods to paleoclimate studies along the Antarctic Peninsula: Magnetically tracking sediment provenance, ice-rafted debris, and productivity variations in glacial-marine sediment Stefanie A. Brachfeld, Byrd Polar Research Center, Ohio
State University Sediment sequences from the Palmer Deep, Andvord Bay, and the Gerlache Strait have revealed decadal to millennial scale oscillations in sedimentation processes over the past ~3400 years and a significant change in the style of sedimentation prior to the onset of the Neoglacial. These cycles are clearly seen in profiles of magnetic susceptibility. Magnetic susceptibility has become a routinely-measured parameter that permits rapid reconnaissance of fluctuations in the composition of sediment cores, primarily yielding information on the relative abundance of ferromagnetic minerals in the sediment. In addition, there exists a wide range of magnetic parameters that are sensitive to chemical composition, magnetic particle size, and the abundance of "non-magnetic" phases. These parameters contain a great deal of information regarding sediment provenance and processes affecting the erosion, transport, deposition, and subsequent chemical alteration of the sediment in which they sit. This poster illustrates the environmental applications of magnetic methods using examples from the western Antarctic Peninsula and the Larsen-A region on the eastern margin of the peninsula. We use sediment trap material, surface sediment from grab samples, and down-core work to examine linkages between environmental processes and magnetic mineral assemblages in modern and historic sediment. We evaluate the roles of paleoproductivity, ice-rafting, sediment provenance, and post-depositional diagenesis in controlling the observed decadal to millennial-scale features of the susceptibility records, and evaluate the potential to correlate and dates these records using geomagnetic field variations. |
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