Date of this Version
ANDRILL Contribution number 4 (June 13, 2005), 18 pages. ISBN: 0972355014. Also available at: http://www.andrill.org/static/Resources/Publications/MIS-Prospectus.pdf.
Response of Antarctic ice sheets to projected greenhouse warming of up to 5.8!C by the end of the century is not known. Models on which predictions are based need to be constrained by geological data of the ancient ice sheets during times when Earth is known to have been warmer than today. The marine-based West Antarctic Ice Sheet (WAIS) and its fringing ice shelves are hypothesized (Clark et al., 2002; Weaver et al., 2003; Stocker, 2003) and documented (Scherer et al., 1998) to have collapsed during past “super-interglacial” warm extremes when global sea-level was more than 5m higher than today. Recent collapse of small ice shelves along the Antarctic Peninsula (Doake and Vaughn, 1991; Skvarca, 1993; Rott et al., 1996; Vaughn and Doake, 1996; Doake et al., 1998; Rott et al., 1998; Skvarca et al., 1999; Rott et al., 2002) highlights the vulnerability of these glacial components to global warming. The Ross Ice Shelf appears to represent one of the most vulnerable elements of the WAIS system. Future demise of the RIS, on timescales of decades to centuries, may well provide an important precursor to eventual WAIS collapse.
The key aim of this research project is to determine past ice shelf responses to climate forcing, including variability at a range of timescales. To achieve this aim the ANtarctic Geological DRILLing Program (ANDRILL) will drill a stratigraphic hole from a platform located on the northwest corner of the Ross Ice Shelf - the McMurdo Ice Shelf (MIS) sector, east of Hut Point Peninsula, Ross Island. Drilling will be undertaken in the austral summer of 2006-2007. The primary target for the MIS site is a 1200m-thick body of Plio-Pleistocene glacimarine, terrigenous, volcanic, and biogenic sediment that has accumulated in the Windless Bight region of a flexural moat basin surrounding Ross Island (Harwood et al., 2003). A single ~1000m-deep drill core will be recovered from the bathymetric and depocentral axis of the moat in approximately 900m of water. The drilling technology will utilize a sea-riser system in a similar fashion to the Cape Roberts Project (CRP), but will employ a combination of hydraulic piston coring (in upper soft sediments) and continuous wireline diamond-bit coring. Innovative new technology, in the form of a hot-water drill and over-reamer, will be used to make an access hole through ~ 200m of ice and to keep the riser free during drilling operations.
This prospectus outlines the background and scientific rationale for the McMurdo Ice Shelf (MIS) Project and presents specific scientific questions to be addressed. It provides a basis for prospective research participants to assess the merits of the MIS Project, and to make their applications to participate in the ANDRILL Program.