HR: 0800h
AN: C21B-1101    [Abstracts]
TI: Biogenic and Stable Isotopic Evidence for Holocene Stability of the Larsen-B Ice Shelf
AU: * Ishman, S
EM: sishman@siu.edu
AF: Southern Illinois University-Carbondale, Department of Geology , Carbondale, IL 62901 United States
AU: Prentice, M
EM: mike.prentice@unh.edu
AF: University of New Hampshire, Institute for the Study of Earth, Oceans, and Space, Durham, NH 03824 United States
AU: McCallum, S
EM: mccallums@ornl.gov
AF: Oak Ridge National Laboratory, P.O Box 2008 MS6036 , Oak Ridge, TN 37831 United States
AU: Leventer, A
EM: aleventer@mail.colgate.edu
AF: Colgate University, Department of Geology, Hamilton, NY 13346 United States
AU: Domack, E
EM: edomack@hamilton.edu
AF: Hamilton College, Department of Geosciences, Clinton, NY 13323 United States
AB: Foraminiferal, diatom and stable isotopic analyses of Kasten core sediments collected from the former Larsen-B region of the eastern Antarctic Peninsula margin reveal details of the recent ice shelf collapse and a Holocene record of environmental change. Downcore trends in foraminiferal distributions indicate relative environmental stability. Cores collected near the former ice shelf margin show faunal fluctuations, possibly associated with variability in sub-ice shelf meltwater production. Both planktonic and benthic foraminiferal δ¹⁸O exhibit a decrease of about 0.5 ‰ from early to late Holocene that we interpret as reflecting a decrease in ocean δ¹⁸O that is at least regional in scale. Through the mid-Holocene, N. pachyderma and G. subglobosa δ¹⁸O coincide indicating negligible local melting. In the late Holocene, planktonic and benthic δ¹⁸O diverge with benthic δ¹⁸O holding steady while planktonic δ¹⁸O decrease further. This implies steady LIS-B melting since the late Holocene. Diatom abundances are negligible in the Larsen-B cores with increases occurring in the latest Holocene. This is in contrast to abundances an order of magnitude higher observed in Holocene sediments to the north. In addition, a core collected from the outer continental shelf shows little Holocene foraminiferal variability indicating relatively stable environmental conditions within the outer region. These data are consistent with sedimentological and petrologic data as well.
DE: 0429 Climate dynamics (1620)
DE: 0473 Paleoclimatology and paleoceanography (3344, 4900)
DE: 0728 Ice shelves
DE: 0793 Biogeochemistry (0412, 0414, 1615, 4805, 4912)
DE: 1041 Stable isotope geochemistry (0454, 4870)
SC: Cryosphere [C]
MN: Fall Meeting 2005