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Victoria University Antarctic Research Expedition Science and Logistics Reports 2000-01: VUWAE 45
Summary of contributions by Hicock
Summary of contributions by Hicock
Allan Hills: (Figure 2).
| a) | A ledge on Weller sandstone was discovered immediately northwest of "Boulder Ridge", which had impressive striae, grooves, rat tails, chattermarks (within grooves), and nail head striae caused by a southward advance of the Manhaul glacier at some time after deposition of the Sirius Group. These erosional features are associated with immature diamict and suggest that, at this place, the Manhaul was not cold based. A future Master's thesis could be done mapping the diamict and erosional evidence of the Manhaul, Odell, and other glacial lobes issuing from the main East Antarctic Ice Sheet. Surface exposure dating of stones in the diamict would be useful to reconstruct the timing of these post-Sirius glacial events. Sandstone boulder dispersal trains in Trudge Valley by the Manhaul Glacier, and quartzite by the Odell Glacier, further attest to the dynamic behaviour under those glaciers. |
| b) | The ridge under the Odell glacier that parallels Trudge Valley may have been formed by the Odell overriding the dolerite dyke that crosses the valley at that place. Subsequently, the Odell may have dumped and streamlined sediment on the lee side of the dyke - the ridge could be a 'crag-and-tail' feature. |
| c) | The ridges on the "Triangle" resemble recessional (ribbed) moraines. |
| d) | Abundant roches moutonnees were discovered on the sides and bottoms of the SE gully, and adjacent gully to the northwest where Bornholdt worked. These are cirque basins that had local ice flowing downhill into Trudge valley. |
Mt. Feather: (Figure 4)
Two boulder pavements were discovered in Sirius diamictite at the outcrop on the eastern corner of the Sirius Group plateau. Data collected imply that lodgement was the main process in pavement formation. Ice flow appears to have been across the bench of Sirius, roughly perpendicular to modern Ferrar glacier flow on the southeast side of Feather. Beneath the pavements is a dark grey comminution tillite that directly overlies Weller interbedded shale and coal which were overridden, deformed, and reconstituted to form the tillite.
Table Mountain: (Figure 5)
The southern edge of the Sirius platform resembles the distal side of a lateral moraine which could explain why it is the southern limit of Sirius at Table Mountain. It may mark the edge of an outlet glacier (ancestral Ferrar or Tedrow) that issued from the East Antarctic Ice Sheet to the southwest, sweeping eastward around an intrusive knob and over the north slope of Table.
Below TM-1 (Dickinson 1997) is a basin carved into Terra Cotta siltstone with Sirius exposed in its north side (not drilled in 1996 but studied by James Goff). This appears to be an old cirque, complete with recessional moraines resting on its floor and even over its northern edge. It could be that the ancestral outlet glacier overrode or pushed against the cirque glacier which prevented the deposition of Sirius in the basin proper.