HR: 15:25h
AN: PP32C-08    [PDF]
TI: A Comparison of West Antarctic and East Antarctic Response to High-Frequency Climate Change During the Holocene
AU: * Kryc, K A
EM: kkryc@pangea.stanford.edu
AF: Stanford University, Dept. of Geol. and Environ. Sciences, Stanford, CA 94305-2115 United States
AU: Dunbar, R B
EM: dunbar@stanford.edu
AF: Stanford University, Dept. of Geol. and Environ. Sciences, Stanford, CA 94305-2115 United States
AU: Murray, R W
EM: rickm@bu.edu
AF: Boston University, Dept. of Earth Sciences, Boston, MA 02215 United States
AU: Manley, P L
EM: manley@middlebury.edu
AF: Middlebury College, Dept. of Geology, Middlebury, VT 05753 United States
AU: Leventer, A
EM: aleventer@mail.colgate.edu
AF: Colgate University, Dept. of Geology, Hamilton, NY 13346 United States
AU: Wang, J
EM: aznkidd55@hotmail.com
AF: Stanford University, Dept. of Geol. and Environ. Sciences, Stanford, CA 94305-2115 United States
AU: Mukherji, S
EM: mrjiggles007@yahoo.com
AF: Stanford University, Dept. of Geol. and Environ. Sciences, Stanford, CA 94305-2115 United States
AB: Based on results from Ocean Drilling Project Site 1098 in the Palmer Deep, we have a highly resolved record of West Antarctic Holocene climate evolution as traced by terrigenous provenance, terrigenous accumulation, nutrient utilization, and surface and export production. Biogenic opal, Corg, and P accumulation rates all increase $\sim$2000 years B.P., reaching a maximum $\sim$5500 to 7000 years B.P. Opal concentrations are less variable, yet indicate that biosiliceous production increased during the mid-Holocene. 13C/12C in bulk organic matter are high (with values similar to ice-edge bloom products) $\sim$4500 to 7000 years B.P., signifying stronger diatom bloom events during the mid-Holocene. Prior to$\sim$3000 years B.P., $\delta$15N was lower for $\sim$2000 years, resulting from less complete utilization of photic zone nitrate. The Al/Ti ratio indicates a change in terrigenous composition $\sim$3500 years B.P. indicating a change in source, weathering style, and/or intensity. To date, there are few comparable records from the East Antarctic Margin. Here, we present preliminary results from a 25-meter core recovered from the MacRobertson shelf of East Antarctica. These sediments are laminated diatomaceous muds comprising a two-component system of biogenic opal (20-50%) and terrigenous material, very similar in character to the Palmer Deep sediments. Our current age model is based on a total of 10 AMS C14 dates. Opal concentrations at this site do not vary considerably through the middle to late Holocene. However, during the early Holocene there appear to be large and frequent changes in opal. This interval is not as prolonged as that shown in the Palmer Deep, but it does indicate that opal concentrations in both East Antarctica and West Antarctica behaved somewhat concurrently during the early Holocene. Whether this is the result of a similar mechanism remains to be determined.
DE: 1040 Isotopic composition/chemistry
DE: 1050 Marine geochemistry (4835, 4850)
DE: 3022 Marine sediments--processes and transport
DE: 3344 Paleoclimatology
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting