Abstract:
The age of the Sirius Group glacial deposits in the Transantarctic Mountains are a topic of debate. There are two conflicting models which try to explain the origin of diatoms found in tillite beds in the glacial deposits. One is that the diatoms were from the Antarctic interior and were subsequently eroded and deposited in the tillite. The second model is that the three million year old diatoms
... were blown by wind into the tillite and incorporated by periglacial processes. This study aimed to distinguish between these two models. The distribution of Sirius Group tillite deposits on Table Mountain, Mount Feather and Mt Crean were mapped with a staff and abney level. The Sirius deposit was then sampled at various depth intervals using a hand operated percussion tool. Fifteen samples were taken in the top section and seven in the bottom section at Table Mountain. The in situ fabric (the orientation and size distribution of the pebbles) was measured to find the mean flow direction of the glacier which deposited the moraine. At Mt Feather, >50 samples from three sites of the Sirius deposits were sampled. At both sites, neighbouring snow samples were collected, melted, filtered and the residue collected to check for currently existing diatoms. In an extension of this study, analysis of the samples revealed authigenic chabazite within Table Mountain samples but not those from Mount Feather. Investigations were undertaken to assess the formation of chabazite under the conditions found at Table Mountain. 
