33
The mineralogical composition of unconsolidated sediments around Shirmacher
(Srivastava et al. 2013) shows quartzose provenance and comprises quartz, feldspar,
amphiboles, pyroxene, kyanite, sillimanite, andalusite, zoisite, chlorite with heavy
minerals such as: garnet, zircon, tourmaline, rutile, spinal, topaz and opaques. The
clay minerals include chlorite, illite, smectite, kaolinite, and vermiculite.
2 Geomorphology
Different aspects of geomorphology, sedimentation, long-distance transport of
debris and palaeo-environmental changes of Schirmacher have been dealt by several
workers which include Bardin (1971), Richter and Bormann (1993), Asthana and
Chaturvedi (1998), Asthana et al. (2009), Shrivastava et al. (2009, 2018), Srivastava
et al. (1988), Ravindra et al. (1991, 2001), Sinha and Chatterjee (2000), Sinha et al.
(2000), Bera (2004), Sharma et al. (2007), Phartiyal (2014), Phartiyal et al. (2011)
etc. among others. The Schirmacher Oasis is conspicuous in displaying rolling
topography constituted by low lying hills. It is devoid of sharp peaks, horns etc. A
thin moraine cover is omnipresent in Schirmacher, displaying the retreating ice
mass over the oasis subsequent to Last Glacial Maxima. The sharp vertical escarpment, faulting and comparatively higher relief on the northern margin of Schirmacher
hills, suggests an isostatic rebound that caused upliftment of the ice free oasis.
Several erosional and depositional landforms such as honey comb weathering, cavernous pits, en-echelon pattern of Roche Moutonees and depositional features e.g.
moraines, patterned ground etc., respectively have been mapped in Schirmacher
Oasis (Ravindra 2013). About a hundred odd melt water lakes of Schirmacher have
been classified genetically in proglacial, landlocked and epishelf lakes (Ravindra
2001). The alignment of most of the lakes have been found to follow some lineaments which define the palaeocourse of the tongues of continental ice sheet moving
towards the shelf in general NNE or NW directions. The architectural pattern of the
Oasis is the net result of polar and peri-glacial environment.
While Asthana and coworkers (op. cit) have dealt with sedimentological aspects
and morphological features of quartz grains in glacial sediments, a detailed geomorphologic map of Schirmacher region on 1:25,000 scale has been published by
Geological Survey of India (2006). Richter and Stranch (1983) and Sinha et al.
(1999) have published results of isotope hydrology and hydro-geochemistry of
Schirmacher.
3 Methodology
Sediment samples were collected from different depositional environments. These
were examined to mark the most abundant constituents and sieved for different size
fractions. Heavy minerals were separated, and their provenance decided on the basis
Glacial Sediments of Schirmacher Oasis, East Antarctica and their Characteristics
The mineralogical composition of unconsolidated sediments around Shirmacher
(Srivastava et al. 2013) shows quartzose provenance and comprises quartz, feldspar,
amphiboles, pyroxene, kyanite, sillimanite, andalusite, zoisite, chlorite with heavy
minerals such as: garnet, zircon, tourmaline, rutile, spinal, topaz and opaques. The
clay minerals include chlorite, illite, smectite, kaolinite, and vermiculite.
2 Geomorphology
Different aspects of geomorphology, sedimentation, long-distance transport of
debris and palaeo-environmental changes of Schirmacher have been dealt by several
workers which include Bardin (1971), Richter and Bormann (1993), Asthana and
Chaturvedi (1998), Asthana et al. (2009), Shrivastava et al. (2009, 2018), Srivastava
et al. (1988), Ravindra et al. (1991, 2001), Sinha and Chatterjee (2000), Sinha et al.
(2000), Bera (2004), Sharma et al. (2007), Phartiyal (2014), Phartiyal et al. (2011)
etc. among others. The Schirmacher Oasis is conspicuous in displaying rolling
topography constituted by low lying hills. It is devoid of sharp peaks, horns etc. A
thin moraine cover is omnipresent in Schirmacher, displaying the retreating ice
mass over the oasis subsequent to Last Glacial Maxima. The sharp vertical escarpment, faulting and comparatively higher relief on the northern margin of Schirmacher
hills, suggests an isostatic rebound that caused upliftment of the ice free oasis.
Several erosional and depositional landforms such as honey comb weathering, cavernous pits, en-echelon pattern of Roche Moutonees and depositional features e.g.
moraines, patterned ground etc., respectively have been mapped in Schirmacher
Oasis (Ravindra 2013). About a hundred odd melt water lakes of Schirmacher have
been classified genetically in proglacial, landlocked and epishelf lakes (Ravindra
2001). The alignment of most of the lakes have been found to follow some lineaments which define the palaeocourse of the tongues of continental ice sheet moving
towards the shelf in general NNE or NW directions. The architectural pattern of the
Oasis is the net result of polar and peri-glacial environment.
While Asthana and coworkers (op. cit) have dealt with sedimentological aspects
and morphological features of quartz grains in glacial sediments, a detailed geomorphologic map of Schirmacher region on 1:25,000 scale has been published by
Geological Survey of India (2006). Richter and Stranch (1983) and Sinha et al.
(1999) have published results of isotope hydrology and hydro-geochemistry of
Schirmacher.
3 Methodology
Sediment samples were collected from different depositional environments. These
were examined to mark the most abundant constituents and sieved for different size
fractions. Heavy minerals were separated, and their provenance decided on the basis
Glacial Sediments of Schirmacher Oasis, East Antarctica and their Characteristics