Sedimentary processes in two different polar periglacial environments: Examples from Schirmacher Oasis and Larsemann Hills, East Antarctica

Abstract

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.

Soils of East Antarctic oasis: interplay of organisms and mineral components at microscale

“…being characterized by further regression of the continental ice sheet, lowering of the lakes water tables and drying of the land. The main agents of the recent sediment transport within the oasis are surface runoff of the snow and ice meltwater (Asthana et al, 2013) which generate sandy surface deposits on the foothills and in depressions. Medium sand is the dominant grain size fraction.…”

Palaeoclimatic records from Antarctica and Southern Ocean: A review of Indian contributions

“…Several studies have been made on lake sediments from Schirmacher Oasis and Larsemann Hills in Antarctica to better understand the past changes in lacustrine environments (Govil et al, 2011(Govil et al, , 2012Shrivastava et al, 2012;Asthana et al, 2013). Phartiyal et al, (2011) have tried to reconstruct the evolution of the Schirmacher Oasis from 13 ka BP to the present.…”

“…Field observations, granulometric analyses of sediment and morphological studies of selected quartz grains in Schirmacher Oasis and Larsemann Hills showed similar results, except for the extent and strength of glacial and glaciofluvial processes. Change in energy conditions is evident from the distribution pattern of sediments in both places (Asthana et al, 2013). Sedimentological properties of surface sediments from lakes of Schirmacher Oasis and Larsemann Hills helped to understand the sedimentary and glacial erosional processes taking place in the two regions.…”

Lake Sediment Studies in Schirmacher Oasis and Larsemann Hills, East Antarctica – An Indian Perspective

“…All the sediment samples were all poorly to very poorly sorted, fine-skewed to nearsymmetrical and platykurtic to leptokurtic in nature. Srivastava et al (2013) also performed mineralogical and geochemical studies on glacial sediments collected from different locations in Schirmacher Oasis. Mineralogically, the sediments are predominantly made up of quartz and feldspar in higher proportion, and a large variety of heavy minerals: zircon, tourmaline, rutile, garnet, hornblende, hypersthene, enstatite, kyanite, sillimanite, andalusite, zoisite, lawsonite, chlorite, spinel, topaz, and opaques.…”

“…The sediments underwent low degrees of chemical weathering (incipient to moderate) and the overall conclusion made through this study was that although there were minor differences amongst the sediments collected from different locations, they represented similar geochemical and mineralogical characteristics. Asthana et al (2013) studied the sedimentological properties of surface sediments from Schirmacher Oasis and Bharati Promontory, Larsemann Hills with an aim to understand the sedimentary and glacial processes taking place in the two regions. In addition to sedimentological data, scanning electron microscopic (SEM) observations on quartz grains were also made to strengthen the data.…”