| Autor: |
Asthana, Rajesh, Shrivastava, Prakash K., Beg, M. Javed, Swain, Ashit K., Dharwadkar, Amit, Roy, Sandip K., Srivastava, Hari B. |
| Zdroj: |
Geological Society, London, Special Publications; 2013, Vol. 381 Issue: 1 p411-427, 17p |
| Abstrakt: |
Schirmacher Oasis and Bharati Promontory in Larsemann Hills of East Antarctica are currently ice-free coastal areas exposed in physiographically different polar periglacial environments. Schirmacher Oasis is bound by the presence of a vast stretch of ice shelf in the north and the polar ice sheet in the south. It exhibits well-developed patterned ground, abundant till deposition, block-fields, episodic development of curvilinear morainic ridges, extensive outwash plains and erratics. In contrast, the occurrence of such depositional features is sparse on Bharati Promontory, where landmass is directly in contact with the ocean. The sedimentary processes vary in their magnitude owing to different physiographic settings in these two geographically separated locations. Scanning electron microscopy of quartz grains shows subsequent reworking under glaciofluvial environment and final deposition of material in glacially scoured basins. The fluvial action is more pronounced in the Schirmacher Oasis than on Bharati Promontory. The transport of sediment by polar ice is mainly through englacial pathways with a minor contribution from the supraglacial component. Discharge of all sizes of sediments ranging from large boulders to glacially abraded rock-flour in varying proportions takes place at the ice–bedrock interface. Granulometric analysis also shows turbulence of transporting media and reworking of sediments before final deposition. |
| Databáze: |
Supplemental Index |
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