Using diamict and glacio-tectonised samples to determine previous glacial overriding in the Allan Hills nunatak

The character and form of previous glacial overriding in the Allan Hills nunatak was determined by describing and quantifying the glacio-tectonised bedrock from Sirius related glaciations. The Sirius Group is an ancient glacial deposit that crops out at high elevations throughout the Transantarctic Mountains (TAM). Sirius diamicts (50) were sampled for analysis using the micromorphology technique to understand the character and regime of the Sirius glaciations. A bulk texture analysis samples was also taken in concert with every micromorphology sample. The samples came from 40 different sites, all of which were triangulated, photographed and given a context description. The description and quantification of glacio-tectonised bedrock from a recent (non-Sirius) advance of the local Manhaul Glacier was conducted and 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 diamict found in the Allan Hills. Where appropriate glacio-tectonised bedrock fractures were quantified using strike and dip measurements. Sketches were drawn of glacio-tectonised bedrock deformation thought to be related to the advance of the Manhaul Glacier. All sites were photographed and described with principle fractures quantified by strike and dip measurements. For comparative reasons, Sitius Group tillite was sampled from Mt Feather (a different natured tillite), the highest known Sitius Group tillites in all of the TAM, and prepared for thin sections.