HR: 0800h
AN: PP51E-1361    [Abstracts]
TI: Seismic and Sediment Data From Herbert Sound, Northwestern Weddell Sea, Indicate a Long-Lived Holocene Ice Canopy
AU: * Maher, J A
EM: juliam@rice.edu
AF: Department of Earth Science, Rice University, MS-126 6100 Main St., Houston, TX 77005 United States
AU: Wellner, J S
EM: jksmith@rice.edu
AF: Department of Earth Science, Rice University, MS-126 6100 Main St., Houston, TX 77005 United States
AU: Anderson, J B
EM: johna@rice.edu
AF: Department of Earth Science, Rice University, MS-126 6100 Main St., Houston, TX 77005 United States
AB: Seismic data and sediment cores from Herbert Sound, northern James Ross Island, Antarctica, were examined in order to constrain the timing of advance and retreat of the Peninsula Ice Sheet into the region during and after the Last Glacial Maximum (LGM). Approximately 124 km of high-resolution seismic data and sixteen sediment cores were collected during a 1982 Deep Freeze cruise and a 1991 Polar Duke cruise. Core analysis included lithographic descriptions, magnetic susceptibility, density, and grain size analysis. Seismic facies analysis indicates regionally tilted Cretaceous bedrock draped with strongly laminated deposits thinning into condensed sections along the fjord walls. Combined core and seismic analysis suggests that there is no significant till present and that the laminated seismic facies consist of glacial-marine and hemipelagic deposits. Subcrops of Cretaceous bedrock indicates ice sheet grounding in the fjord in recent time. Preliminary analysis shows the presence of only volcanic terrigeneous ice rafted material from James Ross Island within thick sections of consolidated clast-rich unfossiliferous glacial-marine sediments, and an apparently thin diatomaceous drape. The combined evidence implies an expanded ice sheet that grounded in the sound followed by glacial-marine deposition from a long-lived ice canopy followed by hemipelagic sedimentation in seasonally ice-free seas. The data indicates that the ice canopy persisted through the late Holocene. Radiocarbon ages are pending on samples from the condensed sections. These dates will be used to better constrain the timing of glacial events in Herbert Sound and relate these events to those that occurred elsewhere in the Antarctic Peninsula.
DE: 4863 Sedimentation
DE: 4207 Arctic and Antarctic oceanography
DE: 4558 Sediment transport
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2004 AGU Fall Meeting