HR: 0800h
AN: PP41A-0629    [Abstracts]
TI: Mid Holocene Warmth in the Antarctic Peninsula: evidence from the Vega Drift
AU: * Patterson, M
EM: mpatterson@mail.colgate.edu
AF: Geology Department, Colgate University, Hamilton, NY 13346 United States
AU: Leventer, A
EM: aleventer@mail.colgate.edu
AF: Geology Department, Colgate University, Hamilton, NY 13346 United States
AU: Drake, A
EM: allison.drake@colorado.edu
AF: INSTAAR Stable Isotope Laboratory, University of Colorado, Boulder, CO 80302 United States
AU: Domack, E
EM: edomack@hamilton.edu
AF: Department of Geosciences, Hamilton College, Clinton, NY 13323 United States
AU: Buffen, A
EM: abuffen@mail.colgate.edu
AF: Geology Department, Colgate University, Hamilton, NY 13346 United States
AU: Ishman, S
EM: sishman@geo.siu.edu
AF: Department of Geology, Southern Illinois University, Carbondale, IL 62901 United States
AU: Szymcek, P
EM: pszymcek@gmail.com
AF: Department of Geology, Southern Illinois University, Carbondale, IL 62901 United States
AU: Brachfeld, S
EM: brachfelds@montclair.edu
AF: Dept. Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043 United States
AU: Backman, E
EM: ebackman@hamilton.edu
AF: Department of Geosciences, Hamilton College, Clinton, NY 13323 United States
AB: Jumbo piston core NBP0003-38, a 20.53 meter core from the Vega Drift (Erebus and Terror Gulf, northeastern Antarctic Peninsula), contains a high resolution record of climate extending back ~8500 years. Lithologic and foraminiferal data presented previously document mid-Holocene conditions warmer than today. These data include increased clay concentration, higher concentrations of ice-rafted debris, and higher magnetic susceptibility below ~6000 ybp, the consequence of extensive meltwater and iceberg calving. This change in lithology is accompanied by the presence of a benthic foraminferal assemblage characteristic of the western Antarctic Peninsula, as contrasted to a lower productivity assemblage observed in the upper section of core. New diatom data confirm mid-Holocene warmth, as based on analysis of the distribution of the two varieties of the species Eucampia antarctica. They are distinguished by their symmetry, with the asymmetric E. antarctica var. antarctica characteristic of subpolar waters and the symmetric E. antarctica var. recta a polar form. Increased relative abundance of the sub-polar form occurs between ~4000-7000 ybp, overlapping and then post-dating the time interval characterized by increased ice melt. In addition, the ratio of terminal to intercalary valves was analyzed. A direct consequence of chain length, a function of the amount of growth, this ratio has been used to record oscillations in winter sea ice cover. Data from JPC38 show longest chain lengths (and least winter sea ice) from ~4000-7000 ybp, in concert with the dominance of the sub-polar form of the species. These data suggest the possibility that mid-Holocene warmth at this site was associated with the southward migration of sub-polar waters and consequently less winter sea ice.
DE: 3344 Paleoclimatology (0473, 4900)
DE: 4207 Arctic and Antarctic oceanography (9310, 9315)
DE: 4900 PALEOCEANOGRAPHY (0473, 3344)
SC: Paleoceanography and Paleoclimatology [PP]
MN: Fall Meeting 2005