Sediment distribution and sedimentary processes across the Antarctic Wilkes Land margin during the Quaternary

The study of existing cores collected across the Wilkes Land margin provides us with a better understanding of the sediment distribution and processes across this margin during the Holocene, and during Pleistocene glacial and interglacial cycles. Holocene depositional rates are high in deep (>1000m) inner-shelf basins where diatomaceous ooze is deposited at estimated minimum sedimentation rates ranging from 40 to 60 cm/kyr. In the shelf troughs, Holocene sediment has a patchy distribution or is totally absent. This is also the case on the shelf banks due to differential deposition because of the irregular relief of the continental shelf and the erosion and redistribution by bottom currents. Pleistocene interglacial sedimentation is well represented in sediment from the continental rise and is dominated by hemipelagic deposition of massive mud with the highest biogenic content (as indicated by %opal) and with a high abundance of clasts (IRD). During the Pleistocene glacial cycles, diamictons were deposited in the continental-shelf troughs and on the banks. Reworking (e.g., by bottom currents) and remobilization (e.g., gravity flows) of these diamictons is a common process along the shallow continental-shelf banks. On the continental slope and the continental rise, gravity flows are one of the most important sedimentary processes. Sediment from continental-slope cores, with a texture that greatly resembles the diamictons on the shelf, is interpreted to represent either part of a slump block or the start of a debris flow. Downslope, crudely stratified to laminated intervals represent the transition between an end member of a debris flow and a turbidity flow. Some of the laminated intervals in cores from the continental rise represent sediment deposited from a turbidity flow. Ages obtained from cores further support that slumps and gravity flows are dominant processes in this margin, because numerous hiatuses apparently are present in cores from the base of the slope. One of these cores extends into the Miocene. Elsewhere on the continental rise, massive and laminated sediments in cores of similar length record near-continuous Pleistocene sedimentation. r 2003 Elsevier Science Ltd. All rights reserved.