Hassler, Lauren E. and Cowan, Ellen A. (2002): Characteristics of ice-rafted pebbles from the continental rise sediment drifts west of the Antarctic Peninsula (sites 1095, 1096, and 1101)

Leg/Site/Hole:
ODP 178
ODP 178 1095
ODP 178 1096
ODP 178 1101
Identifier:
2003-022406
georefid

10.2973/odp.proc.sr.178.212.2001
doi

Creator:
Hassler, Lauren E.
Appalachian State University, Department of Geology, Boone, NC, United States
author

Cowan, Ellen A.
Istituto Nazionale di Oceanografia e di Geofisica Sperimentale, Italy
author

Identification:
Characteristics of ice-rafted pebbles from the continental rise sediment drifts west of the Antarctic Peninsula (sites 1095, 1096, and 1101)
2002
In: Baker, Peter F. (editor), Camerlenghi, Angelo (editor), Acton, Gary D. (editor), Brachfeld, Stefanie A., Cowan, Ellen A., Daniels, James, Domack, Eugene W., Escutia, Carlota, Evans, Andrew J., Eyles, Nicholas, Guyodo, Yohan J. B., Hatfield, Kate L., Iorio, Marina, Iwai, Masao, Kyte, Frank T., Lauer, Christine, Maldonado, Andres, Moerz, Tobias, Osterman, Lisa E., Pudsey, Carol J., Schuffert, Jeffrey D., Sjunneskog, Charlotte M., Weinheimer, Amy L., Williams, Trevor, Winter, Diane M., Wolf-Welling, Thomas C. W., Ramsay, Anthony T. S. (editor), Proceedings of the Ocean Drilling Program, scientific results, Antarctic glacial history and sea-level change; covering Leg 178 of the cruises of the drilling vessel JOIDES Resolution; Punta Arenas, Chile, to Cape Town, South Africa; sites 1095-1103; 5 February-9 April 1998
Texas A&M University, Ocean Drilling Program, College Station, TX, United States
178
Pebbles (>10 mm) sampled from three drill sites on the continental rise west of the Antarctic Peninsula during Ocean Drilling Program Leg 178 were classified by shape and roundness. In addition, pebble lithology and surface texture were visually identified. To increase the pebble sample number to 331, three sites that were drilled 94 to 213 km from the continental shelf edge were integrated into the data set using magnetostratigraphy for core correlation. Pebbles were compared in three groups defined by the same stratigraphic intervals at each site: 3.1-2.2 Ma (late Pliocene), 2.2-0.76 Ma (late Pliocene-late Pleistocene), and 0.76 Ma to the Holocene. Pebble lithologies originate from sources on the Antarctic Peninsula margin. Most pebbles are metamorphic and sedimentary pebbles are rare (>6%), whereas mafic volcanic and intrusive igneous lithologies increase in abundance upsection. Pebbles from 3.1 to 0.76 Ma, plotted on sphericity-roundness diagrams, indicate original transport as basal and supraglacial/englacial debris. Pebbles are abundant and of diverse lithology. From 0.76 Ma to the present, the number of pebbles is low and their shape characteristics indicate they originated as basal debris. Observed changes in ice-rafted pebbles can be explained by growth of an ice sheet and inundation of the Antarctic Peninsula topography by ice approximately 0.76 Ma. Prior to this, outlet and valley glaciers transported debris at high levels within and at the base of the ice. The mass accumulation rate of sand fluctuates and includes rounded quartz grains. Ice-sheet growth may have been accompanied by overall cooling from subpolar to polar glacial regimes, which halted meltwater production and enhanced the growth of ice shelves, which consequently reduced sediment supply to icebergs.
Coverage:Geographic coordinates:
North:-64.2220
West:-78.2916East: -70.1540
South:-67.3401

Stratigraphy; Antarctic Ocean; Antarctic Peninsula; Antarctica; Cenozoic; clastic sediments; climate change; continental rise; cores; drift; glacial geology; grain size; Holocene; ice; ice rafting; icebergs; Leg 178; lithofacies; lithostratigraphy; magnetostratigraphy; marine sediments; Neogene; Ocean Drilling Program; ocean floors; ODP Site 1095; ODP Site 1096; ODP Site 1101; paleo-oceanography; paleoclimatology; pebbles; Pleistocene; Pliocene; Quaternary; sea ice; sediments; Tertiary; upper Pliocene;

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