Antarctic Science

Physical Sciences

Provenance changes between recent and glacial-time sediments in the Amundsen Sea embayment, West Antarctica: clay mineral assemblage evidence

Werner Ehrmanna1 c1, Claus-Dieter Hillenbranda2, James A. Smitha2, Alastair G.C. Grahama2, Gerhard Kuhna3 and Robert D. Lartera2

a1 University of Leipzig, Institute of Geophysics and Geology, Talstraße 35, D-04103 Leipzig, Germany

a2 British Antarctic Survey, NERC, High Cross, Madingley Road, Cambridge CB3 0ET, UK

a3 Alfred Wegener Institute for Polar and Marine Research, Am Alten Hafen 26, D-27568 Bremerhaven, Germany

Abstract

The Amundsen Sea embayment is a probable site for the initiation of a future collapse of the West Antarctic Ice Sheet. This paper contributes to a better understanding of the transport pathways of subglacial sediments into this embayment at present and during the last glacial period. It discusses the clay mineral composition of sediment samples taken from the seafloor surface and marine cores in order to decipher spatial and temporal changes in the sediment provenance. The most striking feature in the present-day clay mineral distribution is the high concentration of kaolinite, which is mainly supplied by the Thwaites Glacier system and indicates the presence of hitherto unknown kaolinite-bearing sedimentary strata in the hinterland, probably in the Byrd Subglacial Basin. The main illite input is via the Pine Island Glacier. Smectite originates from the erosion of volcanic rocks in Ellsworth Land and western Marie Byrd Land. The clay mineral assemblages in diamictons deposited during the last glacial period are distinctly different from those in corresponding surface sediments. This relationship indicates that glacial sediment sources were different from modern ones, which could reflect changes in the catchment areas of the glaciers and ice streams.

(Received July 30 2010)

(Accepted March 25 2011)

(Online publication May 18 2011)

Metrics