HR: 17:45h
AN: PP32D-08    [PDF]
TI: Recent History of the NW Corner of the Ross Ice Shelf, Antarctica, from Sediment Cores
AU: * Barrett, P
EM: peter.barrett@vuw.ac.nz
AF: Antarctic Research Centre, Victoria University of Wellington, P O Box 600, Wellington, 6002 New Zealand
AU: Dunbar, G
EM: gavin.dunbar@anu.edu.au
AF: Antarctic Research Centre, Victoria University of Wellington, P O Box 600, Wellington, 6002 New Zealand
AU: Carter, L
EM: l.carter@niwa.cri.nz
AF: National Institute of Atmosphere and Water, Private Bag 14-981, Kilbirnie, Wellington, 6010 New Zealand
AU: Giorgetti, G
EM: giorgetti@unisi.it
AF: Dipartimento di Scienze della Terra, Via Laterina 8, Siena, 53100 Italy
AU: Niessen, F
EM: fniessen@awi-bremerhaven.de
AF: Alfred-Wegener-Institut f�r Polar- und Meeresforschung, Columbusstrasse, Bremerhaven, D 27568 Germany
AU: Nixdorf, U
EM: unixdorf@awi-bremerhaven.de
AF: Alfred-Wegener-Institut f�r Polar- und Meeresforschung, Columbusstrasse, Bremerhaven, D 27568 Germany
AU: Pyne, A
EM: alex.pyne@vuw.ac.nz
AF: Antarctic Research Centre, Victoria University of Wellington, P O Box 600, Wellington, 6002 New Zealand
AU: Riesselman, C
EM: criessel@pangea.stanford.edu
AF: Department of Geological and Environmental Sciences, Stanford University, Stanford, 94305-2115 United States
AU: Robinson, N
EM: natalie.robinson@vuw.ac.nz
AF: Antarctic Research Centre, Victoria University of Wellington, P O Box 600, Wellington, 6002 New Zealand
AB: Cores of sea floor sediments beneath the Ross Ice Shelf behind Ross Island contain a record of sub-ice shelf sedimentation over the last 20,000 years. The sediments have been accumulating in a 900-m-deep depression resulting from the loading of Erebus volcano, and are being deposited from relatively slow (5-10 cm/sec) currents whose average flow direction is eastward (from McMurdo Sound toward the central Ross Sea). Cores from the two sites were both 60 cm long, but significantly different in character. The core from site 1 was taken about 5 km east of the shelf edge where the ice is 70 m thick. It is an unconsolidated pebbly sandy mud from 62 to 34 cm below the sea floor, where it changes over a cm to a soft fine sandy mud that dominates the rest of the core. Samples yielded uncorrected AMS bulk organic carbon ages of 24,550 years at 34 cm, 18,080 years at 21 cm and 4343 years at 1 cm, indicating an average sedimentation rate of 0.03 mm/year. The changes in sedimentary facies are taken to record a shift of the grounding line landward followed by establishment of the present open circulation that continued to the present day. The low shear strength throughout the core shows that the ice shelf was not grounded, even at the height of the Last Glacial Maximum. The core from site 2, which lies 12 km east of the shelf edge beneath 140 m of ice, is entirely a soft terrigenous sandy mud with a higher diatom content than the upper part of site 1, but similar in other respects. It yielded ages from 12,797 years at 59 cm, 6562 years at 29 cm and 2701 years at 2 cm, indicating a higher sedimentation rate (0.06 mm/year), and records relatively constant conditions throughout that time. The facies and chronology suggest that the Ross Ice Shelf front has not retreated significantly from its present position during the Holocene. The cores also indicate the potential value for recovering a history for the Ross Ice Shelf back to Pliocene times through the proposed coring of Windless Bight by the ANDRILL consortium to 1000 m below the sea floor.
UR: http://andrill-server.unl.edu/
DE: 3022 Marine sediments--processes and transport
DE: 4207 Arctic and Antarctic oceanography
DE: 5416 Glaciation
DE: 9310 Antarctica
SC: Paleoceanography and Paleoclimatology [PP]
MN: 2003 Fall Meeting