Antarctic CRC Marine Geoscience, Prydz Bay, Mac.Robertson Shelf and Kerguelen Plateau, 1995 : Post-cruise Report : AGSO Cruise 149, ANARE Voyage 6, 1994/95 (BANGSS)

This record is a summary of the preliminary results of the second AGSO/Antarctic Co-operative Research Centre/ANARE marine geoscience program in Prydz Bay, the Mac.Robertson Shelf, Antarctica and the Kerguelen Plateau (Fig.1). The cruise program consisted 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 water mass reorganisation in the Southern Ocean during Quaternary climate change episodes. The cruise is designated AGSO survey 149 in AGSO's data bases and has the acronym BANGSS (Big ANtarctic Geology and Seismic Survey) in Antarctic Division data sets. The cruise program set out in O'Brien et al., (1995) was to meet the common goal of the Antarctic CRC Natural Variability (sediments) sub-program and the ASAC strategic plan for Antarctic Geosciences which is 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). Studies of modern sediment transport and modern organisms that contribute to Quaternary sediments were designed to aid the understanding of the ancient sedimentary record and the modern Antarctic environment. Seismic lines and sampling on this cruise were also expected to provide insights into the tectonic and stratigraphic development of the parts of the Antarctic margin. The three features targeted for study during the cruise were: (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) sediments on the Kerguelen Plateau. These features were selected because in anticipation that they should provide insights into Antarctic environmental history. Sediments deposited in Prydz Bay should contain a record of ice sheet fluctuations because of their location at the downstream end of the largest outlet glacier draining from the East Antarctic Ice Sheet, the Lambert Glacier. The Mac.Robertson Shelf, in contrast, was glaciated by ice originating entirely in the adjoining coastal region. It also contains deep basins that contain thick Holocene sediments that are useful in the detailed study of post-glacial environmental change. The Southern Ocean is a major component of the global climate system. Its water masses play a pivotal role 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.