Textural characteristics, distribution pattern and provenance of heavy minerals in glacial sediments of Schirmacher Oasis, east Antarctica

Abstract

Heavy minerals of twenty sediment samples, belonging to polar ice sheet, lake, mainland area and shelf region of Schirmacher Oasis, east Antarctica, have been studied for their textural characteristics, abundance and provenance determination. The heavy crop is represented by zircon, tourmaline, rutile, garnet, hypersthene, hornblende, chlorite, enstatite, lawsonite, kyanite, sillimanite, zoisite, andalusite, spinel, topaz and opaques. The assemblage, in general, is dominated by hornblende-hypersthene-garnet assemblage, followed by kyanite-sillimanite-andalusite and zircontourmaline-rutile. The high concentration of specific minerals of metamorphic origin reveals high-grade metamorphic terrain as the primary source. The ZTR ratio is low showing low mineralogical maturity. An attempt has also been made to compare the trends of heavy minerals of various sub glacial regions with those of the average values of entire area. GEOLOGY AND GEOMORPHOLOGYSchirmacher Oasis (Lat. 70°44' 30" S to 70°46'30" S and Long. 11°22'40" E to 11°54'00" E), is roughly elongated in E-W direction and covers an area of about 35 sq km with a maximum of 2.7 km width in central part. High-grade metamorphic suite of rocks represented by banded-gneiss, alaskite, garnet-biotite, calc-gneiss, khondalite, augen-gneiss and streaky-gneiss are the dominant lithologies. The terrain is heavily criss-crossed by the dykes of basalt, lamprophyre, pegmatite, dolerite etc (Sengupta, 1986).

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

“…The mineralogical composition of sedimentary parent material for the studied soils resembles that of the source rocks -Precambrian gneiss. This agrees with the results of Srivastava et al (2010) on the heavy mineral assemblages from the Schirmacher Oasis sediments which correspond to the local metamorphic bedrock and demonstrate low maturity. In general, that is typical for the sediments, generated within the glacial geosystems (Nesbitt and Young, 1996), where sediment composition is controlled by physical breakdown and fluvial sorting with minimal contribution of biochemical weathering (Caracciolo et al, 2012).…”

Grain size statistics and depositional pattern of the Ecca Group sandstones, Karoo Supergroup in the Eastern Cape Province, South Africa

“…grain sizes and texture). Recently, the use of more sophisticated multivariate statistical methods like factor analysis and discriminant functions have yielded more successful results in identifying the correct depositional process and environments and this is supported by the works of [21][22][23][30][31][32]. This study provides the first relatively detailed grainsize analysis of sandstones from part of the Ecca Group in the study area.…”

“…The bivariate plots are based on the assumption that statistical parameters reliably reflect differences in the fluid-flow mechanisms of sediment transportation and deposition [30]. Several researchers like [19,21,[30][31][32]64] have proven and documented that bivariate plots serve as reliable tools for identifying mechanisms of different environments of sedimentation. Furthermore, they reported that the bivariate plots are the most important and frequently used plots [4,63,65,66] These plots have also been attempted to differentiate between marine and fluvial sands.…”

Grain-size characteristics of deposits derived from different glacigenic environments of the Schirmacher Oasis, East Antarctica

“…The poor sorting of the sediments from the lakes and the ice-free area is also primarily the result of the activity of wind and meltwater. The source of the sediments consists mainly of the highly metamorphosed host rocks and intrusions, as shown by the heavy minerals: zircon, tourmaline, rutile, garnet, hornblende, zoisite, lawsonite, chlorite, spinel, topaz and opaque minerals (Srivastava et al, 2010). These minerals are set free from the host rock by glacial erosion and frost action.…”

“…Modern glacial sediments accumulate due to weathering of the basement, deposition of sediments by the ice sheet, meltwater currents, settling of sediments in lakes, wind activity, etc. The oasis has been studied for its general geology (Sengupta, 1986;Singh, 1986), heavy minerals (Lal, 1986;Srivastava et al, 2010), the geochemistry of the basement (Hoch & To-bschall, 1988;Hoch, 1999;Hoch et al, 2001), structural and thermal characteristics of graphite (Parthasarathy et al, 2003), bedrock topography and subsurface structure (Sundararajan & Rao, 2005), Holocene climate change (Sharma et al, 2007), climatological interpretation of clay minerals (Srivastava et al, 2011), and the geomorphological evolution of the oasis, including modeling of its lacustrine regime from 13 ka ago to nowadays (Phartiyal et al, 2011).…”