Legacy product - no abstract available

Legacy product - no abstract available

The Natural Variability and Past Environmental change Sub-program of the Co-operative Research Centre for Antarctic and Southern Ocean Environments aims to use the records contained in ice and sediments to understand past environmental change to calibrate climatic models. The marine geoscience program for Voyage 7 consists of a sea bed sampling program designed to . Elucidate sedimentation processes on the Antarctic shelf and slope. . Provide sediment cores from the Antarctic shelf and slope for the study ofQuaternary environmental change. Sampling is proposed for Prydz Bay and the adjoining Mac. Robertson Shelf. Prydz Bay is an important site for studying the past behaviour of the Lambert Glacier-Amery Ice Shelf system which is the largest ice stream draining the East Antarctic Ice Sheet. The adjacent but contrasting Mac. Robertson Shelf may not have experienced the same style of glaciation during the Quatemary and has accumulated biogenic sediments in places. Bathymetry and 3.5kHz echo sounder data from Prydz Bay reveal features formed by erosion and deposition beneath the Amery Ice Shelf. The extent of post-glaciation iceberg gouging can also be inferred. On the Mac. Robertson Shelf, sediment accumulations suitable for coring can also be interpreted from the 3.5 kHz records. Fifteen gravity cores at sites selected to help interpret the Late Quaternary history of Prydz Bay and the Mac. Robertson Shelf will be collected on Voyage 7 of the 1992/93 Antarctic Division shipping season, on the R.V. Aurora Australis. An additional core from BANZARE Bank, the southern-most extension of the Kerguelen Plateau will be collected for palaeotemperature studies at the Co-operative Research Centre for Antarctic and Southern Ocean Environments. Grab samples will also be collected to elucidate modem sediment types in Prydz Bay and the Mac. Robertson Shelf.

This report describes the results of geomagnetic measurements made at repeat stations in the northern Prince Charles Mountains (PCMs) in January 1992 and at Heard Island in February 1992. The PCM survey covered 7of the 9 stations occupied by Crosthwaite in Jan/Feb 1990. The Heard Island work was a reoccupation of a previous magnetic station and observatory site. Multiple sets of DIF or HDF observations were made at each station and sunshots, pier differences and local F surveys were carried out at most stations for confirmation of the 1990 measurements. Variometer records for the 3-5 day occupation of each station were obtained using two portable fluxgate magnetometers developed by F Chamalaun, Flinders University. One was left installedat the first repeat station, the other was carried and reburied at each repeat station. The area covered by the survey was approximately 160 km by 130 km. Station descriptions based mainly on those provided by Crosthwaite are included to facilitate reoccupation. References to earlier geophysical and surveying occupations are given in Crosthwaite (1992).

This report presents the results of geomagnetic measurements made at two repeat stations off the coast of Kemp Land Antarctica in October 1989, and at nine repeat stations in the northern Prince Charles Mountains, and Mac Robertson Land Antarctica in January and February 1990. From five to fifty sets of declination, inclination and total field observations (and sunshots to determine azimuth references) were made at each station. The repeat stations are within 500 km of the Mawson Geomagnetic Observatory.

The work described in this report was part of the Bureau of Mineral Resources' contribution to the 1988 Australian National Antarctic Research Expedition. The period of data covered in this report is from 00:00UT 01-01-1988 to 23:59UT 31-12-1988.

This report describes the operation of the Mawson geophysical observatory for 1990. The observatory continuously records the geomagnetic field and global seismic activity at Mawson, and was part of the Bureau of Mineral Resources (BMR) contribution to the Australian National Antarctic Research Expeditions (ANARE). The period covered by this report is from 1 January 1990 to 30 November 1990.

The Natural Variability Sub-program of the Co-operative Research Centre for Antarctic and Southern Ocean Environments aims to study past environmental change by examining ice core and sedimentary records in Antarctica and the Southern Ocean. As the first stage in marine sedimentological studies, Voyage 7 of the Australian National Antarctic Research Expeditions (ANARE) 1992/1993 shipping season included a geoscience program comprising echo sounder traverses, gravity coring and grab sampling of the Antarctic continental shelf and slope on the Mac. Robertson Shelf and in Prydz Bay. This record describes the preliminary results of the voyage and presents location information for core and grab samples and preliminary descriptions of grab samples and lists of subsamples taken by associated research programs.

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.

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