HR: 0800h
AN: C51B-0392    [Abstracts]
TI: New Results and Future IPY Investigations in Hektoria Trough, Inner Larsen-B Embayment, Antarctic Peninsula
AU: * Brachfeld, S
EM: brachfelds@mail.montclair.edu
AF: Department of Earth and Environmental Studies, Montclair State University, Montclair, NJ 07043, United States
AU: Domack, E W
EM: edomack@hamilton.edu
AF: Department of Geosciences, Environmental Studies Program, Hamilton College, Clinton, NY 13323, United States
AU: Leventer, A
EM: aleventer@mail.colgate.edu
AF: Department of Geology, Colgate University, Hamilton, NY 13346, United States
AU: Willmott, V
EM: vwillmott@gmail.com
AF: Department of Geosciences, Environmental Studies Program, Hamilton College, Clinton, NY 13323, United States
AU: Ishman, S
EM: sishman@geo.siu.edu
AF: Department of Geology, Southern Illinois University, Carbondale, IL 62901, United States
AB: We present new results from a sediment core collected in the inner Larsen-B embayment, Antarctic Peninsula. The 2002 break-up of the Larsen-B Ice Shelf enabled access to the termini of glaciers that formerly fed into the ice shelf. United States Antarctic Program cruise LMG05-02 discovered and mapped an 800-m deep glacial trough off Hektoria Glacier at the northern end of the Larsen-B embayment. Sub-bottom profiling reveals the presence of at least 20-m of unconsolidated sediment in the trough, which varies in character between acoustically laminated, and packages with weak, discontinuous reflectors. A 2.5-m kasten core was recovered from the Hektoria trough during cruise LMG05-02. The sediment consists of silty clay with a minor component of very fine sand, and is laminated in the uppermost meter. Downcore magnetic and geochemical parameters were used to investigate the terrigenous sediment supplied to Hektoria Trough. Bulk sediment geochemistry suggests a constant sediment source that is chemically consistent with upper continental crust. Magnetic parameters reveal several intervals in which the magnetic material supplied to the trough varies in abundance and particle size. We observe shifts at approximately 850, 5900, and 7900 ¹⁴C yr B.P., based on a preliminary age model. Superimposed on these shifts are periodic pulses of coarser material into the trough, which may be related to fluctuations in the location of the grounding line with respect to the core site. Our preliminary age model indicates an average sedimentation rate of 21 cm/kyr, which suggests that the basin fill extends back to perhaps 100,000 yr B.P., a rare archive of the late Pleistocene in an ice proximal site.
DE: 0728 Ice shelves
DE: 1051 Sedimentary geochemistry
DE: 1512 Environmental magnetism
DE: 3022 Marine sediments: processes and transport
DE: 3030 Micropaleontology (0459, 4944)
SC: Cryosphere [C]
MN: 2007 Fall Meeting