Monday, 27 August 2007 - 2:30 PM
1.P1.A-4
Sedimentology and stratigraphy of the ANDRILL McMurdo Ice Shelf (AND-001B) core
L.A. Krissek1, G. H. Browne2, L. Carter3, E. A. Cowan4, G. B. Dunbar3, R. M. McKay3, T. R. Naish3, Ross D. Powell5, J.A. Reed6, T. I. Wilch7, and Andrill-Mis Science Team8. (1) School of Earth Sciences and Byrd Polar Research Center, Ohio State University, Columbus, OH 43210, (2) Geological and Nuclear Sciences, Lower Hutt, New Zealand, (3) Antarctic Research Centre, Victoria University of Wellington, Wellington, New Zealand, (4) Department of Geology, Appalachian State University, Boone, NC, (5) Department of Geology and Environmental Geosciences, Northern Illinois University, DeKalb, IL 60115, (6) Department of Geological and Atmospheric Sciences, Iowa State University, Ames, IA 50011, (7) Department of Geological Sciences, Albion College, Albion, MI, (8) ..
During the 2006-2007 austral season, the ANDRILL McMurdo Ice Shelf Project recovered a core 1285 m long (AND-001B) from Windless Bight in the McMurdo Sound region. This core contains a range of lithologies, including both siliciclastic and volcanic diamictites, sandstones and mudstones; diatomites; and volcanic ash/tuff and one phonolitic lava flow. This sequence has been subdivided into eight lithostratigraphic units and 25 subunits, based on lithological abundances. Eleven lithofacies have been recognized, ranging from open marine diatomites and mudstones to turbidites to ice-proximal massive and stratified diamictites. More than 50 glacimarine sequences have been recognized, bounded by glacial surfaces of erosion. Three distinct stacking patterns are present, showing evidence of glacial advance/retreat/advance with varying degrees of preservation. Carbonate and pyrite are the dominant secondary phases in the core. The pyrite overprint is especially notable in volcanic sediments below ~400 mbsf, where it often obscures stratification and sediment texture.