Pre-cruise Report - Prydz Bay - MacRobertson Shelf and Kerguelen Plateau, February-April 1995 : AGSO Cruise 149, R.V. Aurora Australis

This record describes the background, aims and methods to be employed in the second AGSO/Antarctic Co-operative Research Centre/ANARE marine geoscience program in Prydz Bay and the Mac. Robertson Shelf. The cruise program consists of activities aimed at understanding modern sedimentary processes on the Antarctic margin, understanding the Plio-Pleistocene environmental history of the region and obtaining samples from the Kerguelen Plateau to illuminate the history of watermass reorganisation in the Southern Ocean during Quaternary. Climate change episodes.

The cruise will address goals set by the Antarctic CRC Natural Variability (sediments) sub-program, which are to promote a better understanding of global climate change by providing statements of the Antarctic and Southern Ocean palaeoenvironments over the following time intervals:

(A)0-10,000 years (post-glacial warming)

(B)0-160,000 years (last glacial cycle)

(C) 0-5,000,000 years (Pliocene "warming" of Antarctica)

These goals will be achieved by studying the Antarctic and Southern Ocean sedimentary record for evidence of Antarctic ice sheet and Southern Ocean circulation changes.

The development of accurate predictive models of climate change requires an understanding of the behaviour and interaction of components of global climate systems. The East Antarctic Ice Sheet is one such major component so that the study of its behaviour during past climatic fluctuations should provide key guidelines for climatic modelling. Sediments deposited in Prydz Bay contain a record of icesheet fluctuations because this area is located at the downstream end of the largest outlet glacier flowing from the East Antarctic Ice Sheet, the Lambert Glacier-Amery Ice shelf.

Another major component of the global climate system is the Southern Ocean. Water masses of the Southern Ocean play a pivotal role in world climate by absorbing, transporting and releasing heat and by transferring oxygen, nutrients and CO2 to and from the deep ocean. In

this context, the Kerguelen Plateau has accumulated sedimentary sequences that will contain records of how the polar front and its associated water masses have varied between glacial and interglacial periods.

The three geographical features targeted for study during the cruise are: (A) the trough-mouth fan deposits adjacent to Prydz Bay; (B)sediment traps associated with deep, shelf-basins on the Mac. Robertson Shelf; and (C) depositional basins on the Kerguelen Plateau. In the following sections the existing data bases for these areas are discussed and the objectives for the 1995 cruise of Aurora Australis are presented.

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