Provenance signatures of the Antarctic Ice Sheets in the Ross Embayment during the Late Miocene to Early Pliocene: The ANDRILL AND-1B core record

Significant down-core modal and compositional variations are described for granule- to cobble-sized clasts in the Early Pliocene to Middle/Late Miocene sedimentary cycles of the AND-1B drill core at the NW edge of the Ross Ice Shelf (McMurdo Sound). Long-term shifts in compositional patterns outline an evolving provenance which is interpreted as reflecting the combined effects and complex interactions among variations in ice volume, ice flow patterns and paleogeographic changes linked to the local tectonic and volcanic activity. High-frequency variations and the petrological features of the basement clast fraction provide direct information about the potential source regions during both glacial maxima and minima. Provenance of the more distal material is identified in the region between Ross Island and the Skelton-Mulock glacier area (South Victoria Land) (Plio-Late Miocene section) and in the Darwin Glacier catchment (Miocene section). The provenance shifts can be discussed for their implications on ice dynamic models for the glacial evolution recorded in the western Ross Embayment. Reconstructed ice flow directions are consistent with the glaciological models for the Last Glacial Maximum, and the provenance data corroborate the contributions of both the East and West Antarctic Ice Sheets in influencing the modifications of the ice flow pattern of grounded ice in the western Ross Embayment in Miocene to Pleistocene time. (C) 2009 Elsevier B.V. All rights reserved.