L. De Santis

Sedimentary processes in the Wilkes Land margin: a record of the Cenozoic East Antarctic Ice Sheet evolution

Multichannel seismic data collected off Wilkes Land (East Antarctica) reveal four main units that represent distinct phases in the evolution of the Cenozoic depositional environment. A Cretaceous synrift succession is overlain by hemipelagic and distal terrigenous sequences deposited during Phase 1. Sediment ridges and debris-flow deposits mark the transition to Phase 2. Unit 3 records the maximum sediment input from the continent and is characterized by the predominance of turbidite deposits. During Phase 4 the sediment supply from the continental margin was reduced, and draping and filling were the dominant processes on the continental rise. Unit 4 also contains the deposits of sediment wave fields and asymmetric channel-levee systems. These four units are a response to the Cenozoic evolution of the East Antarctic Ice Sheet. During Phase 1, small ice caps were formed in the innermost continental areas. The ice volume increased under temperate glacial regimes during Phases 2 and 3, when large volumes of melt-water production led to high sediment discharge to the continental rise. Change to a polar regime occurred through Phase 4, when a thick prograding wedge developed on the continental shelf and slope and the sediment transport to the rise diminished, producing general starvation conditions.

Submarine glacial landforms on the cold East Antarctic margin

The East Antarctic continental margin, which extends from the Weddell Sea to the Ross Sea (Fig. 1h), surrounds the largest and oldest ice mass on Earth; however, it has only been studied at a few locations because of its remoteness and persistent sea ice. The shelf is 100–150 km wide over most of its length but broadens where major crustal structures intersect it, such as in Prydz Bay (Fig. 1a) where the shelf is 200–300 km wide. This paper reviews what is known presently about the geomorphology of the best-studied sectors of the East Antarctic margin: the deep re-entrant of Prydz Bay and the narrower shelves of George V and Mac.Robertson Land (Fig. 1h). Only a small proportion of the East Antarctica shelf has been surveyed with multibeam bathymetry, so this review is also dependent on compilations of single-beam bathymetry, seismic-reflection profiles and side-scan sonar data. In particular, we use George V Digital Elevation Model (GVDEM, Beaman et al. 2011) and International Bathymetric Chart of the Southern Ocean (IBCSO; Arndt et al. 2013). The slope has been more widely studied, with large amounts of seismic-reflection data available (e.g. Kuvaas & Leitchenkov 1992; Escutia et al. 2000; Solli et al. 2007; Close et al. 2007). Fig. 1. ( a ) Prydz Bay and sub-Amery Ice Shelf bathymetry. (IBCSO v. 1.0; Arndt et al. 2013). ( b ) Long profile of Amery Ice Shelf from upstream of the modern grounding zone to the trough-mouth fan on the continental slope. VE×140. ( c ) Cross-section of Amery Ice Shelf valley at its southern end. VE×20. ( d ) Shaded-relief image of multibeam data collected by N. B. Palmer in 2001 (Leventer et al. 2005). The image covers the transition from streamlined bedrock to moulded basin sediment in the Svenner Channel. Image from GEOMAPAPP (www.geomapapp.org). ( e ) Seismic …

Erratum Journal of the Geological Society, London, Vol. 164, 2007, pp. 243–256. Sedimentary processes in the Wilkes Land margin: a record of Cenozoic East Antarctic Ice Sheet evolution

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