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Victoria University Antarctic Research Expedition Science and Logistics Reports 1999-2000: VUWAE 44
1 Popular Summary of Scientific Work Achieved
1 Popular Summary of Scientific Work Achieved
VUW
This project is a detailed study of ancient glacial deposits termed the Sirius Group at Allan Hills, Southern Victoria Land, Antarctica. The Sirius Group is a collection of Neogene deposits that crop out at high elevations (mostly >1500 m) throughout the Transantarctic Mountains (TAM). Allan Hills occupies a low point in the TAM, making the site more susceptible to overriding by the EAIS during minor volume fluctuations. The aim of this project is to show whether the Sirius Group was deposited by valley glacier or continental ice sheet, by wet- or dry-based glacial ice, by a single depositional event or several overriding events and to determine paleoflow direction.
This past field season ran from mid-November 1999 to mid-January 2000 at Allan Hills during which time field mapping of early glacial deposits was continued from last season. The Sirius Group takes the form of seven patches of thin debris with a total area of 2 km2. From these, eight outcrops were selected for detailed description and sampling. The collected data include: orientations of 300 stones, 270 linear glacial abrasions and 90 planar deformational structures. In addition, 37 rock samples were collected for laboratory analysis. Sample processing has not yet begun but evidence indicates wet-based glacial deposition. Although the number of advances is not yet known, the work thus far suggests flow from the southwest and west. The presence of a cirque incised into a surface capped with Sirius deposits on the south side of Trudge Valley reveals a later phase of local temperate ice before the present cold ice sheet formed.
Univ. of Amsterdam
Allan Hills
Research objectives that are of interest to the University of Amsterdam are three fold. Firstly, description and quantification of glacio-tectonised bedrock from 'Sirius' related glaciations. Research of these features further understanding into the character and form of previous glacial overriding in the Allan Hills nunatak, as well as provides indicators for paleo ice flow direction. Secondly, the collection of Sirius diamict samples for analysis using the technique micromorphology. Micromorphology has proved to be a useful tool in distinguishing between glacial diamicts of different origins world-wide. It is envisaged that micromorphology analysis of these Sirius samples will contribute towards understanding the character and regime of the Sirius glaciation(s). A bulk texture analysis sample was also taken in concert with every micromorphology sample. Thirdly, an objective that was only realised once in the field is the description and quantification of glacio-tectonised bedrock from a recent (non-Sirius) advance of the local Manhaul glacier. Furthermore, a diamict associated with these glacio-tectonised bedrock features was collected for micromorphology (and bulk texture) analysis so to provide an in situ investigation of the only non-Sirius glacial diamict found in the Allan Hills thus far.
Taylor Valley
Three spatially variable micromorphology samples taken from a discontinuous moraine linear ridge at Taylor glacier snout will provide hitherto unknown information on the microstructures of this deposition feature and help resolve the process(es) behind its formation and hence identity. Additional samples were removed from the compact debris-laden basal layer of Taylor glacier to allow in situ textural and structural analysis, by micromorphology, of this subglacial environment.