Controlling factor for nature, pattern and accumulation of the glacial sediments of Schirmacher Oasis, East Antarctica: Comments on paleoclimatic condition

Accepted Manuscript Controlling factor for nature, pattern and accumulation of the glacial sediments of Schirmacher Oasis, East Antarctica: Comments on paleoclimatic condition A.K. Srivastava, P.S. Ingle, N. Khare PII:

S1873-9652(18)30043-4

DOI:

10.1016/j.polar.2018.05.004

Reference:

POLAR 391

To appear in:

Polar Science

Received Date: 28 February 2018 Revised Date:

29 April 2018

Accepted Date: 8 May 2018

Please cite this article as: Srivastava, A.K., Ingle, P.S., Khare, N., Controlling factor for nature, pattern and accumulation of the glacial sediments of Schirmacher Oasis, East Antarctica: Comments on paleoclimatic condition, Polar Science (2018), doi: 10.1016/j.polar.2018.05.004. This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

ACCEPTED MANUSCRIPT 1

Controlling factor for nature, pattern and accumulation of the glacial

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sediments of Schirmacher Oasis, East Antarctica: comments on

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paleoclimatic condition

A. K. SRIVASTAVA1, P. S. INGLE2 and N. KHARE3

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Department of Geology, SGB Amravati University, Amravati-444 602, India

Department of Geology, G. S. Tompe Art’s, Commerce & Science College, Chandur Bazar, Amravati-444 704, India

Ministry of Earth Sciences, Lodhi Road, New Delhi-111 003, India

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[email protected]

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Abstract

The Schirmacher Oasis, East Antarctica is clearly distinguishable into three

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geomorphologic units i.e., i) polar ice sheet, ii) main rocky land including lakes, and iii)

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coastal shelf. These units have different processes for the release and accumulation of

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sediments because of various physical and chemical factors operating either individually or,

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in combination. The cumulative effect of these factors is the accumulation of sediments

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which are normally represented by loose admixture of clasts, sand, silt and clay.

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Sedimentological studies of these sediments provide a good idea about various endogenic and

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exogenic processes going on in the area and their affect on nature and pattern of

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sedimentation as well as paleoclimatic conditions, hydrodynamic, depositional setup, clay

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mineralization. In the present work, compilation and reinterpretation of the work carried out

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in the past on the aspects of granulometry, heavy minerals and clay minerals have been

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carried out together for various geomorphological units and entire area together to interpret

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various factors responsible for sediment accumulation. It has been observed that wind, melt

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water and ice are the main controlling factors for the present scenario of nature and

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composition of glacial sediments of the Oasis. Comments have also been made on the

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paleoclimatic conditions.

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Keywords:

Schirmacher Oasis, Granulometry, Heavy minerals, Clay minerals, East

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Antarctica, Paleoclimate.

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WNW-ESW trending Schirmacher Oasis (Lat. 70o44’30”S to 70o46’30”S and Long.

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11o22’40”E to 11o54’00”E) is a small ice free area in the East Antarctica. The basement is

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represented by hard and compact Precambrian metamorphic rocks (Sengupta, 1986). The

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terrain also acts as a good site of erosional and depositional activities of glacial sediments

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because of periodic changes in temperature condition, repeated annual exposure of the

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basement rocks, high velocity winds and melt water. These processes release and accumulate

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glacial sediments due to wearing and tearing of

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sediments, melt water flow, lake sedimentation and wind actions. These sediments are mostly

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represented by loose admixture of sediments on the Oasis particularly at, i) lake sites, ii)

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sediment accumulations on main rocky land due to melt water channels and wind action, iii)

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southern margin due to melting of polar ice sheet and, iv) northern margin grading to shelf

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region showing coastal sediments. The Oasis, though small in size, provides a good scope for

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the study of the glacial sediments, accumulated due to working of one or more geological

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agents, e.g., the sediments lying adjacent to northern margin of polar ice sheet that are

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accumulated mainly due to unwelding and melting of polar ice and dropping down on ground

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forming small debris of loose sediments. Similarly, the northern margin that grades to shelf

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area of Antarctic Ocean have plenty of ice free, scattered pockets of coastal sediments,

basement, unwelding of ice trapped

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ACCEPTED MANUSCRIPT however, this region also gets sediments from the entire southern area through melt water

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channels originated in main land or, even from the base of polar ice sheet. The main rocky

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land exhibits small accumulations of sediments due to melt water channels and wind action

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apart from numerous glacial lakes having loose admixture of sediments. Transportation and

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deposition of most of the sediments are governed by the activities of melt water channels,

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wind and ice.

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The Schirmacher Oasis is under regular monitoring and investigation by Indian

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scientists as it is one of the national programmes of Government of India by arranging regular

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scientific expeditions to Antarctica. The outcome related with the geological aspects are

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generation and compilation of data on general geology (Singh, 1986; Sengupta, 1996);

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sedimentology (Lal, 1986; Asthana and Chaturvedi, 1998); hard rock petrography (Kumar,

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1986; Jayapaul et al., 2005); magnetic characteristic of the region (Gupta and Verma, 1986);

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pollen-spores (Sharma et al., 2002; Bera, 2004); diatom flora (Palanisamy, 2007); ecological

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assessment of fresh water lake (Ingole and Dhargalkar, 1998); bedrock topography and

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subsurface structure (Sundararajan and Rao, 2005); structural and thermal studies of graphite

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(Parthasarathy et al., 2003); Holocene climatic changes (Sharma et al., 2007, Phartiyal et al.,

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2014); geomorphology including categorization of lakes (Ravindra, 2001, Phartiyal et al.,

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2011), granulometric analysis (Srivastava and Khare, 2009; Srivastava et al., 2012); heavy

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minerals (Srivastava et al., 2010), clay mineralogy (Srivastava et al., 2011), mineralogy and

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geochemistry (Srivastava et al., 2011) etc. The process and episodes of metamorphic rock

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formation including lamprophyres have been carried out by Hoch and Tobschall (1988),

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Hoch (1999) and Hoch et al. (2001).

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The Oasis, offers good scope of work on various aspects of glacial sediments,

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however, limited to grain size analyses (Lal, 1986; Asthana and Charturvedi, 1998;

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Srivastava et al., 2012), heavy minerals (Srivastava et al., 2010), mineralogy and

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ACCEPTED MANUSCRIPT geochemistry (Srivastava et al., 2011). As such, any attempt to decipher controlling factors

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for source, nature and pattern of glacial sediments is still lacking. These sediments also reveal

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past environment and climate under which they were deposited. Our prime aim in this work is

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to fill these gaps existing. In the present attempt, three significant aspects of these sediments,

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i.e., i) granulometry, ii) heavy minerals and, iii) clay mineralogy have been discussed with a

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view to explore their mode of nature, abundance and controlling factors in entire are as well

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as in various geomorphologic units. These aspects of study have also been used to interpret

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the climatic conditions in the past.

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2. Geomorphological units

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The WNW-ESE trending Schirmacher Oasis is a narrow strip of land with the

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geographical spread of about 35 km2, having a maximum width of 2.7 km in the central part.

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Its southern side is covered by polar ice sheet whereas, northern is marked by the ice shelf on

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Antarctica. Broadly, the area shows an undulating topography due to the existence of

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numerous low altitude hills up to 200m and shallow depressions occupied by melt water

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forming glacial lakes. Precambrian crystalline terrain, represented by high grade

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metamorphic suit of rocks forms the basements (Sengupta, 1986) (Fig. 1). Despite the

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domination of high grade metamorphic terrain, there is an ample scope for the study of

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glacial sediments released by on-going glacial activities. Considering together the

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geomorphological and glacial features, the Oasis and its surroundings, from south to north,

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can be subdivided into three major units i.e., i) polar ice sheet (PIS), ii) main rocky land of

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Schirmacher (MRL) including lakes (LKS) and, iii) coastal shelf (CSH) area (Srivastava et

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al., 2011) (Fig. 2). All these units extend roughly in WNW-ESE directions as of the Oasis.

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The polar ice sheet, a regional feature, covers a large area in the south, lying adjacent

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to the main rocky land. At a few places, its northern boundary is exposed in the form of

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ACCEPTED MANUSCRIPT vertical cliff showing horizontal layering in the ice which are easily differentiable because of

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their varied thickness, transparency, shades of brown colour and degree of melting (Fig. 3A).

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The ice sheet also shows the impregnation of abundant silt and sand size sediments which get

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accumulated at the bottom of melt water channels, depressions formed on the surfaces of ice

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as well as on scarp face. The easy sites to collect the sediments from ice sheet lie along the

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base of vertical cliff where the melt water along with the sediments entrapped in the ice sheet

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drips down on the ground and forms small debris of sediments.

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The second unit is the WNW-ESE elongated main rocky land which is an undulating

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area consisting dominantly of hard metamorphic terrain with scattered rock debris along with

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pockets of rudaceous to arenaceous sediments. Its northern peripheral strip shows a general

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steepness towards the coastal shelf whereas, southern part is abruptly overlain by polar ice

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sheet. Low altitude hills of 50 to 200 m, glacial lakes and plains, U-shaped valleys and

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depressions constitute undulating topography (Fig. 3B). This unit receives as well as release

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the sediments by two major physical agencies i.e., wind and glacier including its melt water.

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Medium to high velocity winds during the ice free period release and reshape the sediments

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through weathering and erosion of the rocks and also contribute in their selective deposition

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in depressions, shadow zones, valleys etc. The glacial actions including melt water channels

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are also responsible in the release and accumulation of the sediments. This unit is also

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characterized by numerous lakes, i.e., land-locked and proglacial lakes on the main land area

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whereas, epishelf lakes are restricted to the northern boundary. These water bodies serve as a

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potential site of sediment accumulation from surrounding high relief area, as well as from

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entire area which is criss-crossed by melt water channels that ultimately disappear in the

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lakes and discharge its sediment load in the same (Fig. 3C). Certain lakes of the main land

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area also discharge in epishelf lakes.

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ACCEPTED MANUSCRIPT The third unit i.e., coastal shelf (CSH) area with a WNW-ESE trend is marked by

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thick cover of perennial shelf ice. Its marginal area coincides with northerly sloping southern

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boundary of the main rocky land. As such, it is difficult to find clear coast because of shelf

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ice cover, however, certain scattered patches of the sediments seem to be deposited by the

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same (Fig. 3D). Besides this, the region is also marked by patches of the mixed sediments as

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the melt water channels and other small glaciers on the main rocky land take a down slope

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route towards the north and finally discharge over this area.

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3. Sampling locations and details

Grab samples were collected consisting of loose admixture of sand-silt and clay

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belonging to thirty-seven locations of the entire area representing various geomorphologic

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units of the Oasis i.e., 08 samples from polar ice sheet (P1-P8), 07 samples from main rocky

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land (M1-M7), 09 samples from lakes (L1-L9) and, 13 samples (S1-S13) from coastal shelf

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area. In case of polar ice sheet, the samples were collected from the sediment accumulations

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formed by the dropping down of the melt water on the ground along the margin of polar ice

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sheet or, in the depressions formed on the surface of ice. Lake sediments were collected from

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the marginal areas, normally lying 15-30 cm inside the water body. Sampling from main

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rocky land and coastal shelf have been made from the sandy patches over the same by

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digging the ground surface for 15-20 cm. Sampling from main land area involves two criteria

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in consideration, i.e., i) main rocky land, where the wind is a significant factor for the release,

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transport and accumulation of sediments besides, the glacial actions including melt water

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channels and, ii) lakes as a sites of sediment discharge by melt water channels in routed from

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uplands and adjoining areas. Figure 2 demonstrates location-wise details of the samples.

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4. Grain size analysis Recently, Srivastava et al. (2009, 2012) generated the grain size data through dry

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sieving technique following Ingram (1971) and Lindholm (1987) and computed various

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textural parameters for entire area and individual units, i.e., PIS, MRL, LKS and CSH as

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proposed by Folk and Ward (1957) and Folk (1980) (Table-1). They observed that the

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sediment admixture of PIS have comparatively higher proportion of medium to fine sand and

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clay, whereas, LKS and CSH sediments are dominantly coarse to fine sand whereas, MRL is

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marked by more quantity of medium to very fine sand. The cumulative weight percentage

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frequency curves of all the samples show a general tendency of horizontal closeness, which

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indicating a poor sorting of grains. The average values of mean size of the sediments

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belonging to various units (Mz) i.e., PIS (av. 1.33 Φ), LKS (av. 1.33 Φ), MRL (av. 1.74 Φ)

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and CSH (av. 1.52 Φ) indicate predominance of medium sand size sediments with local

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variations in the proportions of coarse to fine sand for separate unit. The graphic standard

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deviation (σ1) of the sediments for PIS (av. 1.70 Φ), LKS (av. 1.91 Φ), MRL (av. 1.49 Φ) and

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CSH (av. 1.61 Φ) respectively indicate poor sorting of the grains. Though, the average

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values, show poor sorting of the sediments ranging between 1.00 Φ to 2.00 Φ, however, their

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degree of sorting depicts an increasing trends i.e., LKS
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skewness (Sk1) values broadly show the dominance of fine skewed sediments followed by

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near-symmetrical, excluding PIS sediments which are dominantly very fine skewed in nature.

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The average kurtosis (KG) values shows that the sediments from PIS are mostly mesokurtic

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(av. 1.01 Φ) LKS, platykurtic (av. 0.81 Φ), whereas, MRL (av. 1. 18 Φ) and CSH (av. 1.70

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Φ) are leptokurtic in nature. The entire region shows the dominance of platykurtic sediments

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followed by leptokurtic and mesokurtic, very leptokurtic and very platykurtic sediments are

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of minor representation.

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ACCEPTED MANUSCRIPT Srivastava et al. (2009, 2011) have attempted to find out any possible interrelationship

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of sediments among various geomorphic units. The plot of mean vs. standard deviation shows

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that the sediments of entire area fall in poorly to very poorly sorted categories with minor

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exceptions of moderately sorted sediments. The later may be due to localized phenomenon as

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continuous flow of the melt water causes removal of fine grain material from the sediment

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admixture. The PIS and LKS sediments in the same plot show their clustering at the boundary

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of coarse and medium sand whereas; the MRL sediments lack any definite pattern but tends

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to cluster in the field of fine-grained sediments. The CSH sediments are dominantly of

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medium sand size and poorly sorted. The scatter of mean size vs. skewness shows a pattern of

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comparatively more fine material in medium-grained sand in PIS and LKS sediments, fine

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skewness in fine sand fraction for MRL sediments, whereas, dominantly near-symmetrical to

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fine skewed in coastal shelf. The scatter of mean size vs. skewness shows two groups of

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clustering for the sediments i.e., one group is restricted near the boundary of coarse and

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medium-size sand, whereas, the other have a long range of scatter i.e., entire field covering

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medium to fine sand. The mean vs. kurtosis graph indicates a very weak relationship among

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the sediments of individual units. The plot of standard deviation vs. skewness is not

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convincing as the sediments lack any definite pattern. Standard deviation vs. kurtosis plot of

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the entire area show two trends i.e., i) a faint tendency of increasing kurtosis with decrease in

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sorting in a few sediments of MRL and PIS and, ii) a decrease of kurtosis with decrease of

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sorting in the range of 1.5 Φ to 2.25 Φ values. The skewness vs. kurtosis plot lacks any

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define pattern as there is a wide scatter of points of individual glacial units.

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Testing of group differences have also been attempted to find any possible

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relationship of textural parameters of different glacial units with an assumption that the

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dominant physical parameters of each unit might have played a role in sediment

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accumulation of different nature resulting to variability in textural parameters. It has been

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ACCEPTED MANUSCRIPT done by comparing various populations by performing t- and F- tests applications. The t-test

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has been carried out for mean, standard deviation, skewness and kurtosis of the sediments

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belonging to all the four glacial units as proposed by Davis (1986). Null hypothesis has been

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applied assuming that the mean values of all the glacial units are equal. A total of six

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combinations, e.g., PIS/LKS, PIS/MRL, PIS/CSH, LKS/MRL, LKS/CSH and MRL/CSH,

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have been taken on both equal and unequal variances and tested at 1% and 5% levels of

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significance. The results show that mean of all the six combinations have no significant

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differences of four glacial units and the same trends stand for standard deviation, skewness

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and kurtosis. The F- test was done considering one-way and two-way variances of the

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samples, phi values and textural parameters to test whether the two population variances are

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equal and, also for testing the significance differences between the means of several samples

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as proposed by Dean and Voss (1999); and Walpole et al. (2004). One-Way ANOVA applied

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among the textural parameters of different glacial units i.e., mean, standard deviation,

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skewness and kurtosis on values at 1% and 5% levels shows that all the data are non

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significant. Two-Way ANOVA, applied for samples and phi values for samples are non

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significant; whereas, between phi values, it is significant as the phi values are based on

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diameter of the sediments. Similarly, the samples and textural parameters inclusive of mean,

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standard deviation, kurtosis and skewness for all the four geomorphic units have also been

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calculated. The F-values for textural parameters for PIS and LKS are significant, and non

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significant for CSH at both 1% and 5% levels, as well as MRL for 5%, whereas, the values of

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MRL are significant at 5% and non significant at 1% level.

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Overall granulometric analysis indicates that though, the Oasis is clearly

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distinguishable into four distinct units i.e., PIS, MRL, LKS and CSH area, but their sediments

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characteristics are almost same i.e., poor to very poor sorted. However, certain samples also

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show deviation in their sorting index i.e., medium to well sorted. It is because of the influence

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ACCEPTED MANUSCRIPT of local physical agencies like action of melt water channel or, naturally controlled

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unidirectional wind flow which sorts the sediments as per its own energy conditions.

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Similarly, the changes in textural parameters of the sediments from various geomorphic units

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are interpreted to be because of cumulative effect of geological activities like, wind and melt

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water. Low to high velocity winds normally erodes the sediments, however, settles also in

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shadow zones. These winds are also responsible for the transport of the sediments of entire

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area through mostly traction and saltation modes during low temperature period of 3-4

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months when surface area remains ice-free. The net result of medium to high energy winds is

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the mixing of the surface sediments of entire area resulting poor to very poor sorting of the

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same. The other significant physical agency evolves during this period is the melt water

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channels that come into existence due to rise in temperature. This causes the release and

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transport of entrapped sediments in the ice. This melt-water mostly acts as depositional

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channel because of its low velocity. The finer fragments get deposited in channel affected

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area at proximal or distal distances depending upon the energy condition of the medium and

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slope of the ground. The coarser sediments including clasts normally settle down in proximal

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area. The combined effect of wind and melt-water results into through mixing and haphazard

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distribution of the sediments on exposed area of the Oasis i.e., main rocky land, lakes and

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coastal shelf. During cold months, when Oasis is mostly covered with ice, high velocity snow

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laden winds mostly work as an erosive agent for elevated areas and high altitude peaks.

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Simultaneously, the sediments including clasts carried out by the snow laden winds get

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accumulated on the surface of polar ice, lacking any pattern of sorting or size parameters.

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Both these agents i.e., high velocity winds and melt water together or individually play a

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major role in erosion, transport and deposition of the sediment in and around the Oasis that

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eventually results into continuous reshuffling of the sediments in a uneven manner.

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5. Heavy minerals analysis The available data on heavy minerals by Srivastava et al. (2010) is based on the study

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of five representative samples from each unit i.e., polar ice sheet (P1, P3, P5, P7, P8), lakes

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(L1, L3, L4, L5, L9), main rocky land (M1, M2, M3, M4, M7) and coastal shelf (S1, S4, S8,

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S10, S12) making a total of twenty. The heavy mineral assemblage of entire area consists of

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zircon, tourmaline and rutile (ultrastable); garnet, kyanite, sillimanite, enstatite, zoisite

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(moderately stable), and hornblende, hypersthene and andalusite (unstable) with minor

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occurrences of chlorite, spinel, topaz and lawsonite. The stability index followed is as per

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Pettijohn et al. (1973). Opaque minerals represented dominantly by magnetite, hematite have

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fair representation in the entire assemblage. The grain counts from polar ice sheet, lakes,

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mainland area and coastal shelf indicate that excluding opaques, their is a dominance of

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hornblende, hypersthene and garnet in entire area, however, it may vary for individual glacial

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unit (Srivastava et al., 2010) (Table-2). For example, the assemblages of lake and mainland

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area show higher percentage of hornblende compared to the average of the entire area; garnet

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is less in polar ice sheet sediments but show almost equal representations in lake, mainland

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and shelf area; hypersthene is high in polar ice sheet but low in mainland sediments. The

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variations in the concentrations of heavy minerals in different units are probably because of

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nature and pattern of transporting medium and agent.

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Srivastava et al. (2010) have also attempted to compare the quantitative distribution of

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various heavy minerals in different glacial units. The ultrastable minerals i.e., zircon,

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tourmaline and rutile are comparatively higher in polar ice sediments, however, their trends

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of distribution is almost same in all the units. In case of lake and mainland area, their average

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values are very close as the lakes are a part of the broader domain of main rocky land. In the

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shelf sediments, the ultrastable minerals are comparatively less in percentage as enrichment

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of heavies are not possible due to absence of frequent reworking process because the

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ACCEPTED MANUSCRIPT sediments are entrapped in the ice, however, the trend of their abundance is similar as of

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other units. The same trend has also been noticed for aluminosilicates i.e., kyanite, sillimanite

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and andalusite having highest average values in mainland area, however, sillimanite

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dominates for entire area compared to other two minerals. It is due to the high-grade

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metamorphic terrain that releases the sediments through mechanical weathering of rocks and

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erosion through high velocity winds. Topaz, also follows the same trend i.e., higher average

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value in mainland area including the lakes. Epidotes are comparatively low.

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The ZTR index ranging from 14.3 to 20.99 is low showing immature nature of the

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sediments (Hubert, 1962). The values for mainland (14.3) and lakes (15.26) are

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comparatively low and show rapid erosion, short transportation and quick deposition (Hubert,

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1962). The polar ice sheet and coastal shelf area sediments are comparatively more mature

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than lakes and mainland areas as revealed by little higher index value. The nature and

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abundance of heavy minerals indicate a high-grade metamorphic terrain as the source rock

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which is evident by the dominance of hornblende, hypersthene, garnet, kyanite, sillimanite,

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andalusite, lawsonite and spinel (Mange and Maurer, 1992). It is comparable with high-grade

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metamorphic terrain as the source rock of Weddell sea, Antarctica having dominance of

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mineralogically low mature heavy minerals i.e., garnet, green hornblende and various

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clinopyroxene in glacial-marine surface sediments (Diekmann and Kuhn, 1999). They have

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also commented for the spatial variations of provenance and transport paths of terrigeneous

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sediments from Antarctica sources on the basis of the mineralogical and granulometric

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properties of the sediments around Weddell Sea and adjoining areas. However, the possibility

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of other sources for the supply of sediments cannot be ruled out as rounded, sub-rounded to

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subangular grains of zircon and tourmaline showing transportation have also been recorded.

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Such grains are normally considered as the derivatives of non-metamorphic to low grade

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metamorphic terrains that might have been supplied from schists and gneisses of the area

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ACCEPTED MANUSCRIPT (Deer et al., 1992). The provenance for widespread occurrence of tourmaline may be due to

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pelitic and psammitic source rock (Henry and Guidottic, 1985; Mange and Maurer, 1992).

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Fair representation of rutile and garnet along with kyanite, sillimanite and andalusite clearly

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indicate high grade metamorphic terrain as the source rock (Force, 1980; Mange and Maurer,

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1992) comparable with Paleocene sediments of Seymour island of Larsen ice shelf, northern

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Antarctica (Elliot et al., 1992). Geochemical studies of garnets from various rock units

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exposed in Antarctic Peninsula to identify their sources indicate that most of the garnets

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belong to metamorphic sources (Hamer and Moyes, 1982; Moyes and Hamer, 1983).

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The interpretation of controlling factor for the distribution of heavies in different

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glacial units is difficult as all are characterized by different set of mechanism for sediment

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accumulation, their release and transport. The grain size data of various glacial units show a

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very weak relationship with the distribution of heavy minerals in the area. The average

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glacial sediments of entire area are of medium sand size, poorly sorted, finely skewed and

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mesokrutic in nature, which is also applicable for various glacial units with exception of a

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few samples because of localized action of geomorphic agents (Srivastava et al., 2009, 2012).

312

In this condition, it can be interpreted that the hydrodynamic forces and nature of the terrain

313

can be the controlling factors for heavy minerals concentration rather than the grain size of

314

the sediments. The polar ice sheet, getting the sediments mostly from wind on the top surface

315

show maximum concentration of zircon, tourmaline, rutile, hypersthene, chlorite, enstatite

316

and spinel but low in hornblende and garnet. Simultaneously, high percentages of hornblende

317

and hypersthene along with kyanite, sillimanite, andalusite and topaz in lakes and mainland

318

area depict their local sources rich with the same i.e., existing metamorphic terrain.

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319

In the present case, the nature and composition of the source rock are interpreted to be

320

the major controlling factors for the distribution of heavy mineral in various glacial units.

321

However, they can also get affected by other processes as all the four glacial units are

13

ACCEPTED MANUSCRIPT 322

different in nature. The climatic and weathering conditions, transport mechanisms, reworking

323

of the sediments etc. also affect the distribution as well as the stability of grains which are

324

quite evident in various units of the Oasis (Elliot et al., 1992; Ehrmann and Polozek, 1999).

325 6. Clay mineralogy

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326

Thermal analysis and mineralogy of the clay based on sixteen representative samples

328

i.e., polar ice sheet (P1, P4, P6, P7), main rocky land (M2, M3, M4, M7), lakes (L1, L3, L6,

329

L9) and coastal shelf area (S3, S5, S10, S11) have been provided by Srivastava et al. (2011).

330

The methodology followed for separation of clays from the sediments admixture is as

331

proposed by Jackson (1979). A comparative study of DTA curves of all the samples exhibit

332

almost similar trend showing uniformity of clay mineral contents in the admixture. Since, all

333

the samples are surficial in nature, similar kind of clay mineralogy has been observed. A

334

small notch of endothermic peak around 5850C shows that kaolinite is common in all the

335

samples which may be due to the removal of structural water from the aluminium atoms (O′

336

Gorman and Walker, 1973; Kotoky, 2006). Similarly, the uniform patterns of TGA curves

337

indicate minor loss or gain in the weight that may be because of loss of the bound water in

338

clays (Liptey, 1973). Clay minerals have been identified on the basis from their peak values

339

(Jackson, 1979) six diffractograms of each sample i.e., saturated with Ca, glycolated, treated

340

with K and heated at 250C, 1000C, 3000C and 5500C. Illite, with strong and well defined

341

peaks in all the samples is quite evident along with kaolinite, smectite and vermiculite,

342

whereas, chlorite with low peak is identifiable in a few samples (Table-3). Besides, primary

343

minerals like quartz, feldspar, mica and amphibole are also represented in diffractograms.

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344

In order of abundance, illite is dominant in all the glacial units followed by smectite,

345

vermiculite and kaolinite, however, lacks any trend in individual unit or among various units.

346

A general observation made on the basis of mean values of various clay minerals shows that

14

ACCEPTED MANUSCRIPT illite and smectite are the two most dominant minerals, whereas, kaolinite and vermiculite

348

with low values have almost uniform trends. Illite is widely reported along the Antarctic

349

continental margin and East Antarctic Craton (Drab et al., 2002; Hillenbrand and Ehrmann,

350

2003) and the source of the same in East Antarctica is interpreted to be the biotite-bearing

351

metamorphosed rocks (Holmes, 2000). In glacial environment, this mineral can be produced

352

by weathering of any metamorphic rock of low to high grade as felsic to basic plutons and

353

dykes (Setti et al., 2001). The terrain of Oasis is characterized by high grade metamorphic

354

suite of rocks that probably acted as the source rock for illite in the sediments through

355

weathering of terrain in glacial environment.

SC

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347

Kaolinite is also reported in the sediments of all glacial units with low percentage. It

357

is a widely reported mineral from Antarctic Peninsula (Ehrmann et al., 2003) reported it as

358

prominent mineral of the Cenozoic Battye Glacier Formation, North Prince Charles

359

Mountain, East Antarctica, whereas, low in percentage in the Cenozoic sediments of

360

McMurdo Sound, Antarctica (Ehrmann et al., 2005). In continental area, kaolinite is a

361

common mineral which is considered to be a product of weathering under tropical condition

362

(Biscaye, 1965; Singer, 1984). Keller (1970) opined that the formation of kaolinite i.e.,

363

Al2SiO5(OH)+ is possible by weathering of any aluminium silicate where K+, Na+, Ca++,

364

Mg++ and Fe++ can be easily leached out from the parent rock. Granites and gneisses, rich in

365

feldspars, yield kaolinite after weathering and leaching away of K+ and Na+, mainly under the

366

influence of ground water Keller, 1970. Its formation in glacial environment is a matter of

367

discussion. Ehrmann et al., 2003 and Hillenbrand and Ehrmann, (2003) tried to explain its

368

course and origin in glacial condition and suggested that kaolinite cannot be formed in polar

369

conditions hence, its occurrences in Battye Glacier Formation is due to its formation during

370

the intervals of warmer and wetter conditions due to chemical weathering of some

371

metamorphic rocks or, it is introduced as of detrital origin from a distant source, lying

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356

15

ACCEPTED MANUSCRIPT beneath the ice. In Schirmacher Oasis, the basement consisting of gneissose plateau is rich

373

with feldspar, but, prevailing cold condition is not conducive for its weathering and formation

374

of kaolinite. In this condition, the presence of kaolinite is possibly due to variation of

375

temperature in the past within the limits of prevailing cold climate along with humidity

376

allowing chemical weathering of feldspar and release of kaolinite. It is comparable as the

377

kaolinite is reported from the drill core sediments of Paleocene-Eocene boundary at Maud

378

Rise, Weddell Sea region, East Antarctica as a product of chemical weathering (Robert and

379

Kennett, 1994).

SC

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372

Smectite, present in all the glacial units of the area have a widespread report from

381

Cenozoic and Quaternary sediments of Antarctica as a significant mineral for reconstruction

382

of paleoclimate (Campbell and Claridge, 1987; Robert and Maillot, 1990; Ehrmann and

383

Mackensen, 1992; Ehrmann, 2001; Setti et al., 2000, 2001). Smectite can be added in the

384

sediment of marine set up due authigenesis (Chamley, 1989) or, detrital constituent (Güven,

385

1988). The authigenic origin is suggested mainly due to submarine alteration of volcanic

386

glass and fragments of volcanism due to hydrothermal activity and digenetic processes

387

(Chamley, 1989). The detrital variety is mostly sourced from the nearby areas and acts as a

388

significant tool to interpret source of sediments, weathering pattern and past climate (Güven,

389

1988). The authigenic varieties mostly belongs to nontronites or saponites whereas, detrital

390

smectite corresponds to aluminous montmorillonite-beidellite series (Chamley, 1989; Hiller,

391

1995). Humid and relatively warm climatic conditions, having environments with slow water

392

facilitates its origin in continental area (Chamley, 1989). A detailed study of smectite carried

393

out in two different cores collected from Victoria Land Basin, Antarctica by Ehrmann, (2001)

394

and Setti et al., (2000) respectively show a change in their shape, abundance, concentration

395

and crystallinity at different stratigraphic levels and interpreted the same because of

396

authigenic and detrital modes of smectite genesis at various levels depending upon the

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380

16

ACCEPTED MANUSCRIPT mineralogical composition of host rock, diagenetic processes, climate and hydrothermal

398

fluids. Ehrmann et al., (2003) suggested that the chemical weathering of basaltic rocks gives

399

rise to authigenic smectite whereas, detrital smectite comes from the soil of adjacent

400

continent during humid climate (Hillenbrand and Ehrmann, 2005). The prevailing climatic

401

condition of Schirmacher Oasis supports authigenic origin of smectite as the highly

402

metamorphosed terrain bears many intrusions of basaltic rocks.

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397

Vermiculite, an uncommon mineral of glacial environment, is a part of clay fractions

404

recovered from all the sediments admixture. In continental deposits, it is normally produced

405

because of pedogenic or, diagenetic activities (Hiller, 1995). In Antarctic Peninsula and

406

Antarctic Ocean, it is mostly reported from the soils of Lassiter Coast, south of Antarctic

407

Peninsula (Setti et al., 2004; Prince Charles Mountain (Boyer, 1975; Bardin et al., 1979 and

408

Vandraveroel et al., 2000). The existence of illite-vermiculite mixed layer in Pleistocene

409

sediments of northwestern Atlantic ocean are interpreted to be because of chemical

410

weathering of micaceous phyllosilicates due to erosion of high latitude continental areas

411

followed by their transport by rivers and deep water masses (Bardin, 1982). Similarly, its

412

occurrence from subsurface strata of the continental shelf, Weddell Sea, Antarctica is

413

considered due to hydration of the primary mica (Kristofferson et al., 2000; Drab et al.,

414

2002).

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415

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403

Chlorite is also reported from the study area but their occurrence is restricted in a few

416

samples only. In continental deposits, it is mostly detrital in nature and produced due to

417

intense weathering of feldspar bearing rocks in tropical condition (Biscaye, 1965). However,

418

it is well documented from glaciated regions for its occurrence and origin i.e., Green land ice-

419

sheet (Drab et al., 2002); Antarctic Peninsula (Tingey, 1991) including Victoria Land Basin

420

(Setti et al., 2001); Pagodroma Group (Ehrmann et al., 2003); McMudro Sound (Kristoffersen

421

et al., 2000); (Ehrmann et al., 2003). Jeong and Yoon (2001) reported kaolinite from King

17

ACCEPTED MANUSCRIPT George Island, West Antarctica and interpreted its presence due to weathering of unaltered

423

bed rock. Chlorite in the southern polar areas is considered to added due the physical

424

weathering of metamorphics and igneous rocks forming the basement in which the altered

425

calc-alkaline volcanics acted as the prime major source (Jeong and Yoon, 2001; Hillenbrand

426

and Ehrmann, 2003).

RI PT

422

427 428

7. Paleoclimate

The climate manifests its imprint on grain characteristics, mineralogy and process of

430

deposition at large. In the present case, the sediments studied are detrital in nature having

431

their influx largely from metamorphic terrain of Schirmacher Oasis as the source rock for

432

main land and lakes; whereas, from other unknown sources in case of sediments from polar

433

ice sheet and coastal shelf. All these sediments are under accumulation and reworking

434

processes in the glacial environment from last thousands of years, therefore, attributed with

435

characteristics features of cold climate at present stage. Since, the current study is based on

436

the grab samples, therefore, our interpretations for climate and environment are applicable to

437

recent past only which are based on grain size analysis, heavy minerals and clay.

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429

Grain characteristics including their textural parameters may be considered as one of

439

the proxies of glacial climate. The sediments of Schirmacher Oasis are reported to be angular

440

to subangular in shape and poorly to very poorly sorted in nature which are characteristics

441

features of glacial environment (Asthana and Chaturvedy, 1998; Asthana et al., 2005;

442

Srivastava et al., 2009, 2012; Warrier et al., 2017). As such, paleoclimatic studies for the

443

Oasis are very limited; however, certain attempts had been made for the reconstructions of

444

the same on the basis of lake sediments. Phartiyal et al. (2011) based on magnetic

445

susceptibility and loss on ignition data from seven sediment profiles interpreted the existence

446

of five large lakes in Schirmacher Oasis during Holocene that reduced to smaller lakes in due

AC C

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18

ACCEPTED MANUSCRIPT course of time. They had also interpreted that the present day land-locked lakes were

448

originally glacial lakes as the Oasis was dominated by glaciers during 13-12.5 cal ka B.P.

449

Warrier et al. (2014) revealed environmental magnetic record of glacial-interglacial climatic

450

variations in Schirmacher Oasis and interpreted that the Holocene period was characterized

451

by alternating phases of relatively warm (12.55-9.88 cal. ka B.P.) and cold (9.21-4.21 cal. ka

452

B.P. and from ~2 cal. ka B.P. onwards) events.

RI PT

447

The clay minerals are widely considered as a good proxy of climate (Biscaye, 1965;

454

Chamley, 1981) and have added significance for high latitude areas having frequent climatic

455

variations and intensive erosional processes (Erhamann, 1991). The clay mineral assemblage

456

under study consists of chlorite, illite, kaolinite, smectite and vermiculite of which chlorite

457

has less representation. Chlorite and illite, mostly detrital in nature, are normally introduced

458

in system as a result of physical weathering and glacial erosion. These minerals are typical of

459

high latitude (Holmes, 2000) and have wide spread occurrence in glacial region including

460

East Antarctica (Junttila, 2007). Washener et al. (1999) considered illite as typical mineral of

461

cold climate and interpreted that in Arctic basin it is derived from the surrounding shelf area.

462

Kaolinite in the glacial sediments of Schirmacher Oasis is note worthy as the same cannot be

463

formed under polar conditions (Erhamann et al., 2003; Hillenbrand and Erhamann, 2003;

464

Junttila, 2007). Its formation is normally attributed with weathering of granitic and basic

465

rocks followed by subsequent leaching under tropical condition (Millot, 1964; Biscaye, 1965;

466

Singer, 1970). Here, its presence indicates prevalence of warmer condition in the past, may

467

be during interglacial period. The same is also interpreted for kaolinite of the Battye Glacier

468

Formation, East Antarctica (Erhamann et al., 2003; Hillenbrand and Erhamann, 2003).

469

Smectite, for its use as a proxy of climate, require to have the idea about its mode of origin

470

i.e., due to hydrothermal alteration of volcanic substrate prior to surficial weathering

471

(Chamley, 1989; Mirabell et al., 2005; pedogenic origin (Prudencio et al., 2002; Yousefifard

AC C

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453

19

ACCEPTED MANUSCRIPT et al., 2015 ; aeolian input (Colman, 1982). The smectite, induced in the sediment during

473

warm interglacial period by hydrothermal alteration of volcanic substrate is interpreted from

474

Victoria Land basin, Antarctica (Erhamann, 2001; Setti et al., 2000) and Prydz Bay (Junttila,

475

2007) and the same may be applicable for Schirmacher Oasis as having the similar

476

lithological setting of the terrain.

RI PT

472

477 478

8. Conclusion

The present work has been carried out to interpreted various controlling factors

480

responsible for sediment accumulation on Schirmacher Oasis. It has been observed that

481

existing geomorphologic units of the Oasis i.e., i) polar ice sheet, ii) main rocky land

482

including lakes and, iii) coastal shelf area have their specific methods for the release,

483

transport and accumulation of the sediments. The significant agents identified for the

484

transport and accumulation of sediments are low to high velocity winds, melt water and ice,

485

which strongly controls the nature and pattern of the sediments. Composition of the basement

486

rocks, its weathering and erosion also play significant role in fixing overall mineralogical

487

composition of the sediments. These controlling factors may work separately or in

488

contribution.

EP

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SC

479

The effect of various physical agencies on nature and pattern of sediments can also be

490

noticed through textural parameters of the sediments, heavy mineral and clay mineral

491

assemblages. The granulometric analysis of the glacial sediments of entire area depicts poor

492

to very poor sorting. The factors responsible for lack of any trend in the sediments admixture

493

are because of the physical factors working in the area which are mainly melt water, high

494

energy winds and ice that reshuffle the sediments in a continuous manner, a characteristic

495

feature of glacial climate. In general, it is difficult to differentiate various geomorphic units

496

on the basis of various textural parameters. Heavy mineral assemblage represented by

AC C

489

20

ACCEPTED MANUSCRIPT hornblende, hypersthene, garnet, kyanite, sillimanite, andalusite, lawsonite and spinel depicts

498

metamorphic terrain as the source rock. The ZTR index reflects an immature nature of the

499

sediments. The statistical and comparative studies of these minerals belonging to various

500

geomorphic units lack any definite trend or correlation. The main controlling factors

501

interpreted for the abundance and distribution of heavy minerals in entire area as well as in

502

various units may be the nature and composition of the basement rock. However, reworking

503

of the sediments, transport mechanism, climate change also played significant role. Various

504

clay minerals identified from the entire area, ranging from hydrous aluminum silicate to

505

potassium, magnesium, iron, sodium and calcium rich varieties show almost uniform pattern

506

in their distribution and abundance in various glacial units. It can be interpreted that the

507

formation of these clay minerals is because of significant change in physio-chemical

508

condition operating within the system. These conditions may include variability of the

509

temperature, mineralogical and chemical compositions of the terrain and the sediment

510

admixture derived due to the weathering and erosion of the same.

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497

Interpretation of paleoclimate on the basis of textural and mineralogical parameters of

512

the sediments reveals mainly the evidences of glacial climatic conditions prevailed in the

513

recent past over the Schirmacher Oasis. It is quite obvious that the sediment admixtures

514

studied are the accumulations of recent past only. Chlorite and illite minerals are the typical

515

minerals of high latitudes, marked by the cold climate. However, the presence of kaolinite

516

and smectite suggests increased temperature condition in the past.

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511

518

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519

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520

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South Shetland Islands, West Antarctica, and its implication for the clay mineral composition of marine sediments. J. Sed. Pet. 71, 833-847.

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625

Kumar, R., 1986. Note on the P-T Conditions of metamorphism of Schirmacher Range, East

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629

Schirmacher Oasis and sea bed sediment of Princess Astrid Coast, Queen Maud Land

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Technical Publication No.3, 219-223.

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Liptey, G., 1973. Atlas of Thermoanalytical Curves, Akademiai Kiado, Budapest, 84-85.

633

Mange, M.A., Maurer, H.F.W., 1992. Heavy Minerals in Colour. Chapman and Hall,

634

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632

Moyes, A.B., Hamer, R.D., 1983. Constrating origins and implications of garnet in rocks of

636

the Antarctic Peninsula. In: Oliver, et al. (Eds.) Antarctic Earth Science, Austr. Acad.

637

Sci., Canberra, 358-362.

639 640 641 642 643 644

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638

EP

635

O' Gorman, J.V., Walker, P.L., 1973. Thermal behavior of mineral fractions separated from selected American coals. Fuel. 52, 71-79.

Palanisamy, M., 2007. Snedra ulna (Nitzsch) Ehrenberg: A new generic record in Schirmacher Oasis, East Antarctica. Curr. Sci. 92 (2), 179-181. Parthasarathy, G., Sharma, S.R., Ravinran, T.R., Arora, A.K., Hussain, S.M., 2003. Structural and thermal studies of graphite from East Antarctica. J. Geol. Soc. India 61, 335-343. Pettijohn, F.J., Potter, P.E., Siever, R., 1973. Sand and Sandstone.Springer-Verlag, 618.

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ACCEPTED MANUSCRIPT 645 646 647 648

Polozek, K., Ehramann, W., 1999. Distribution of heavy minerals in CRP-1.Terra. Antarct. 5, (3) 633-638. Phartiyal, B., 2014. Holocene palaeoclimate variation in the Schirmacher Oasis, East Antarctica: a mineral magnetic approach. Pol. Sci. 8, 357-369. Phartiyal, B., Sharma, A., Bera, S.K., 2011. Glacial lakes and geological evolution of

650

Schirmacher Oasis, East Antarctica during late Quaternary. Quat. Internat. 235, 128-

651

136.

654 655

SC

653

Ravindra. R., 2001. Geomorphology of Schirmacher Oasis, East Antarctica. In Proceedings Symp.“On Snow, Ice and Glacier”. Geol. Sur. India Spec. Publ. 53, 379-390. Robert, C., Kennett, J.P., 1994. Antarctic humid episode of Palaeocene-Eocene boundary:

M AN U

652

RI PT

649

clay mineral evidence. Geology 22(3), 211-214.

Robert, C., Maillot, H., 1990. Palaeoenvironments in the Weddel Sea area and Antarctic

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climates, as deduced from clay mineral associations and geochemical data ODP Leg

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TE D

656

Sengupta, S.M., 1986. Geology of Schirmacher range (Dakshin Gangotri), East Antarctica.

660

Sci. Rep., 3rd Ind. Sci. Exp. Antarctica. DOD, Govt. of India Publ. Technical

661

Publication No.3, 187-217.

663

Sengupta, S. M., 1996. Introduction to Sedimentology. Oxford & IBH publishing Co-Pvt.

AC C

662

EP

659

Ltd, New Delhi, 305.

664

Setti, M, Marinoni, L., López-Galindo, A., Delgado Huertas, A., 2000. Compositional and

665

morphological features of the smectite of sediments of CRP-2/2A, Victoria Land

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667

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of CRP-3 drill core (Victoria Land basin, Antarctica): Preliminary results. Terra.

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Antarct. 8(4), 543-550.

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ACCEPTED MANUSCRIPT 670

Setti, M, Marinoni, L., López-Galindo, A., 2004. Mineralogical and geochemical

671

characteristics (major, minor, trace elements and REE) of detrital and authigenic clay

672

minerals in a Cenozoic sequence from Ross Sea, Antarctica. Clay Miner. 39, 405-422.

673

Sharma, C., Bera, S.K., Upreti, D.K., 2002. Modern pollen spore rain in Schirmacher Oasis, East Antarctica. Curr. Sci. 82 (1), 88-91.

RI PT

674

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676

Priyadarshini Lake sediments, Schirmacher Oasis East Antarctica: the palynological

677

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675

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central and southern Portugal: climate significance. Catena 49, 77-89.

684 685 686 687 688 689

Singh, R.K., 1986. Geology of Dakshin Gangotri hill range, Antarctica. Sci. Rep., 3rd Ind.

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Ear. Sci. Rev. 21, 251-293.

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682

Singer, A., 1984. The palaeoclimatic interpretation of clay minerals in sediments: a review.

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AC C

681

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and provenance of heavy minerals in glacial sediments of Schirmacher Oasis, East Antarctica J. Geol. Soc. India 75, 393-402.

690

Srivastava, A.K., Khare, N., Ingle, P.S., 2011.Characterization of clay minerals in the

691

sediments of Schirmacher Oasis, East Antarctica: their origin and climatological

692

implications. Curr. Sci. 100 (3), 363-372.

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Srivastava, A.K., Ingle, P.S., Lunge, H.S., Khare, N., 2012. Grain-size characteristics of

694

deposits derived from different glacigenic environments of Schirmacher Oasis, East

695

Antarctica. Geologos 18 (4), 251-266. Srivastava, A.K., Randive, K.R., Khare, N., 2013. Mineralogical and geochemical studies of

697

glacial sediments from Schirmacher Oasis, East Antarctica. Quat. Internat. 292, 205-

698

216.

701 702

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700

Sundararajan, N., Rao, M., 2005. A note on the petrophysical properties and geological

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696

703

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704

Significance of random illite-vermiculite mixed layers in Pleistocene sediments of the

705

northwestern Atlantic Ocean. Clay Min.35, 679-691.

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707

1991. Clay mineral distribution in surface sediments of the Eurasian Arctic Ocean and

708

continental margins as indicator for source areas and transport pathways a synthesis.

709

Boreas 28, 215-233.

711

EP

Walpole, R.E., Myers, R.H., Myers, S.L., Ye, K. 2004. Probability & Statistics for Engineers

AC C

710

TE D

706

& Scientists. Prentice Hall, 730.

712

Warrier, A.K., Mahesh,B.S. and Mohan, R., Shankar, R., Asthana, R. and ravindra, R. 2014.

713

Glacial-interglacial climatic variations at the Schirmacher Oasis, East Antarctica: the

714

first report from environmental magnetism. Palaeogeog. Palaeoclimatol. Palaeoecol.

715

412, 249-260.

716 717

Warrier, A.K., Mahesh,B.S. and Mohan, R., 2017. Lake sediment studies in ice-free regions of East Antarctica. Proc. Indian Nat. Sci. Acad. 83(2), 289-297.

29

ACCEPTED MANUSCRIPT 718

Yousefifard, M., Ayoubi, S., Poch, R.M., Jalalian, A., Khademi, H., Khormali, F., 2015. Clay

719

transformation and pedogenic calcite formation on a lithosequence of igneous rocks in

720

northwestern Iran. Catena, 133, 186-197.

721

RI PT

722 Captions of Figures and Tables

724

Fig.1. Geological map of the Schirmacher Oasis, East Antarctica (after Sengupta, 1986).

725

Fig. 2. Significant geomorphological units of the Schirmacher Oasis (after Ravindra, 2001)

726

SC

723

and location of sampling sites.

Fig. 3. Photographs showing A) northern face of ice sheet in the south of Maitri showing

728

layers of ice due to differential weathering, the arrows mark the sediment accumulation

729

sites, B) main rocky land with a patch of loose sediments, C) main rocky land and

730

Priyadarshini Lake and, D) shelf exposed in the north of Maitri. The marked area is a

731

patch of loose sediments.

735 736 737 738

TE D

734

Table.1. Graphical measures and textural parameters of samples from various geomorphic units of Schirmacher Oasis (Srivastava et al., 2012).

EP

733

Table.2. Heavy mineral counts and ZTR index of the studied samples belonging to polar ice

AC C

732

M AN U

727

sheet, lakes, main land and coastal shelf (Srivastava et al., 2010).

Table.3. Representations of clay minerals identified in the samples of various geomorphic units (Srivastava et al., 2011).

739 740

30

ACCEPTED MANUSCRIPT

Ф 75

Ф-values Ф 50 Ф 25

4.41 4.45 4.42 4.37 4.32 3.31 3.41 4.24

2.98 2.76 3.41 3.15 2.95 2.69 2.95 2.96

2.74 2.26 3.13 2.81 2.81 1.95 2.76 2.61

1.69 1.51 2.66 1.62 1.97 0.67 1.60 1.12

0.36 0.45 1.57 0.38 1.52 -0.73 -1.14 -0.85

L-1 L-3 L-4 L-5 L-6 L-7 L-2 L-8 L-9

4.25 4.71 3.41 4.45 4.20 4.02 3.89 3.41 3.94

2.94 4.05 2.44 2.83 3.29 3.15 3.08 2.85 3.15

2.71 3.15 1.61 2.21 2.93 2.84 2.80 2.59 2.84

1.49 1.67 0.41 1.25 1.73 1.72 1.61 1.58 1.51

-0.23 0.0 -1.14 0.36 -0.66 -0.87 -0.31 0.48 -1.17

M-1 M-2 M-3 M-4 M-5 M-6 M-7

4.39 3.74 4.12 4.23 2.93 4.28 3.45

3.38 2.81 3.22 3.20 2.39 3.44 2.86

3.10 2.20 2.93 2.93 1.91 3.16 2.55

2.46 1.03 2.37 2.22 1.50 2.64 1.22

S-1

4.22

2.92

2.70

0.66

Ф1

Polar ice sheet -0.94 -1.53 36.5 -0.77 -1.40 40.4 0.74 -1.04 18.1 -0.89 -1.44 38.8 1.06 0.47 14.7 -1.03 -1.37 56.7 -1.77 -2.55 44.0 -1.29 -1.78 48.3 Lake -0.89 -1.43 44.0 -0.49 -1.17 41.7 -1.43 -1.82 68.5 -0.64 -1.38 45.1 -1.31 -2.07 40.4 -1.53 -2.40 40.1 -1.09 -1.75 41.5 -0.58 -1.45 39.5 -1.81 -2.57 46.9 Main land 1.06 0.49 15.0 -1.17 -1.72 49.4 1.23 -0.79 14.1 0.70 -1.68 19.7 0.90 -0.58 35.8 0.47 -1.38 25.9 -1.25 -1.96 47.4 Coastal shelf 0.19 -1.42 32.0

EP 2.02 -0.49 1.62 1.51 1.05 0.75 -0.58

AC C 1.73

Ф5

TE D

P-1 P-2 P-3 P-4 P-5 P-6 P-7 P-8

Ф 16

MZ

σ1

Grain size parameters Sk1 KG SOS

RI PT

Ф 84

SKS

1.24 1.17 2.27 1.29 1.99 0.77 0.98 0.93

1.88 1.78 1.48 1.81 1.00 1.63 2.08 1.98

+0.21 -0.14 +0.38 +0.14 +0.12 +0.11 +0.40 -0.05

1.10 1.32 1.43 0.98 1.22 0.71 0.62 0.71

2.97 2.925 2.73 2.905 1.925 2.34 2.98 3.01

2.56 2.83 0.14 2.57 -0.09 3.34 2.76 3.78

1.18 1.64 0.47 1.14 1.23 1.11 1.20 1.28 0.95

1.81 2.13 1.75 1.74 2.19 2.04 1.89 1.50 2.22

+0.13 -0.006 +0.09 +0.01 +0.26 +0.33 +0.24 +0.25 +0.28

0.73 0.76 0.77 1.29 0.71 0.70 0.74 0.94 0.66

2.84 2.94 2.615 2.915 3.135 3.21 2.82 2.43 3.255

2.7 2.54 4.41 3.33 2.81 2.98 2.42 1.7 3.49

2.3 0.89 2.27 2.07 1.59 2.18 0.94

1.17 2.25 1.23 1.52 0.89 1.59 1.83

+0.10 +0.10 +0.21 +0.25 -0.01 +0.37 +0.19

1.48 0.83 1.53 1.70 1.12 0.96 0.70

1.95 2.73 2.455 2.955 1.755 2.83 2.705

-1.02 3.4 0.17 1.47 0.51 0.38 2.97

1.61

1.53

+0.07

1.13

2.82

2.18

SC

Ф 95

M AN U

Textural features/ Sample No.

ACCEPTED MANUSCRIPT

0.31 1.09 -1.06 0.48 -0.16 -1.26 1.61 -1.05 -0.97 -1.05 -0.91 -0.83

-1.49 0.47 -1.78 -1.36 -1.31 -2.14 0.54 -1.79 -1.97 -1.77 -1.37 -1.52

34.2 14.3 42.0 23.4 28.4 36.3 7.5 37.2 49.4 51.3 60.8 24.3

1.88 1.90 1.31 1.97 1.78 1.11 2.42 1.27 0.97 0.91 1.02 1.73

1.69 0.81 2.08 1.55 1.75 1.91 0.84 1.92 1.75 1.66 1.57 1.92

+0.15 +0.04 -0.06 +0.23 +0.22 +0.37 -0.15 +0.30 +0.08 +0.03 +0.22 +0.52

RI PT

0.56 1.51 -0.26 1.22 0.69 -0.32 1.82 0.07 -0.47 -0.33 0.26 0.51

SC

1.95 1.85 1.62 2.19 2.09 1.72 2.62 1.92 1.02 0.93 1.33 2.59

M AN U

2.95 2.56 2.86 2.14 2.98 2.69 2.90 2.83 2.68 2.42 2.00 3.19

TE D

3.39 2.77 3.39 3.26 3.42 2.87 3.05 3.05 2.86 2.85 2.66 3.44

EP

4.60 3.09 4.56 4.30 4.35 3.76 3.71 4.15 3.35 4.05 3.14 4.18

AC C

S-2 S-3 S-4 S-5 S-6 S-7 S-8 S-9 S-10 S-11 S-12 S-13

1.03 1.03 0.83 1.35 1.05 2.02 1.20 0.88 0.69 0.86 1.05 0.87

3.045 1.31 3.17 2.83 2.83 2.95 1.585 2.97 2.66 2.91 2.255 2.85

2.19 -1.08 3.1 1.28 1.48 2.46 -2.07 2.1 3.28 3.96 1.85 0.52

ACCEPTED MANUSCRIPT

Hornble Hypersthe nde ne

Enstatit e

Kyanite

36 35 08 19 23 24.2

27 36 30 12 09 22.8

22 20 10 16 12 16

43 30 59 33 36 40.2

44 47 38 48 55 46.4

43 30 73 39 54 47.8

08 05 04 23 12 10.4

14 14 08 21 10 13.4

L-1 L-3 L-4 L-5 L-9 Avg.

05 18 16 23 34 19.2

20 20 20 09 18 17.4

08 07 15 11 05 9.2

62 70 52 34 45 52.6

70 56 63 42 49 56

59 48 44 52 26 45.8

02 -19 07 07 7

05 06 17 24 13 13

M-1 M-2 M-3 M-4 M-7 Avg.

29 24 16 07 21 19.4

15 20 18 13 09 15

10 05 08 12 08 8.6

39 61 67 44 52 52.6

123 29 43 36 46 55.4

31 13 50 48 49 38.2

06 03 -15 18 8.4

12 33 24 13 07 17.8

S-1 S-4 S-8 S-10 S-12 Avg. Entire area avg.

33 08 10 25 07 16.6 19.8

24 18 12 08 06 13.6 17.2

09 12 16 08 05 10 13.4

86 65 25 40 48 52.8 49.5

36 53 43 59 64 51 52.2

23 47 49 46 49 42.8 43.6

-08 15 14 07 8.8 8.55

EP

AC C

06 14 14 12 21 13.4 14.4

Andal usite

Polar ice sheet 11 06 14 08 13 02 31 19 12 27 16.2 12.2 Lakes 07 03 10 01 27 09 19 19 43 06 21.2 7.6 Mainland 12 38 29 11 46 11 23 16 20 05 26 16.2 Shelf area 27 02 11 20 20 10 13 31 17 18 17.6 16.2 20.25 13.05

TE D

P-1 P-3 P-5 P-7 P-8 Avg.

Sillima nite

Zoisite

Laws onite

Chlo rite

Spinel

Topaz

Opaque

Total

ZTR Total

ZTR. Index

05 02 -09 01 3.4

02 07 02 11 05 5.4

21 21 12 10 08 14.4

05 09 11 09 03 7.4

06 08 02 08 09 6.6

31 39 39 37 53 39.8

325 325 311 272 329 354.4

85 91 48 47 44 63.0

28.33 30.33 16 15.66 14.66 20.99

---07 04 2.2

06 01 11 15 -6.6

09 15 11 14 12 12.2

11 06 06 07 06 7.2

13 05 13 13 11 11

35 66 65 51 41 51.6

315 329 388 311 320 357.6

33 45 51 43 57 45.8

11 15 17 14.33 19 15.26

-11 02 05 03 4.2

02 07 10 08 04 6.2

17 07 08 08 10 10

03 12 -09 04 5.6

04 22 12 13 09 12

31 19 42 51 84 45.4

372 295 357 321 348 368.6

54 49 42 32 38 43.0

18 16.33 14 10.66 12.66 14.30

--03 04 08 3 3.2

-14 11 16 10 10.2 7.1

20 07 15 16 09 13.4 12.5

12 04 09 05 03 6.6 6.7

03 14 06 05 10 7.6 9.3

32 30 59 42 42 41 44.5

313 325 317 344 324 358 359

66 38 38 41 18 40.2 48.0

22 12.66 12.66 13.66 06 19.90 17.61

RI PT

Garnet

SC

Rutile

M AN U

Heavy Zirc Tourm Min. on aline /Sample no.

ACCEPTED MANUSCRIPT

6.60 7.11 8.00 6.34 3.30 12.38 9.07 11.92 8.86 6.21 13.39 2.01 18.44 11.50 11.00 2.25

9.30 5.87 6.14 5.97 5.82 1.96 5.29 4.54 12.27 3.88 3.72 17.28 2.99 16.43 6.00 16.34

11.50 10.83 13.23 11.94 8.32 11.76 10.58 11.92 15.95 ---32.74 10.37 13.96 11.50 22.00 4.51

RI PT

14.5 9.79 13.31 12.68 9.40 7.60 13.00 9.08 3.54 28.49 10.42 12.10 17.70 17.52 13.00 7.34

K-Feldspar

SC

7.20 4.57 6.14 6.43 6.80 3.67 10.88 11.92 9.82 7.25 4.96 5.76 11.21 10.95 12.00 11.86

Quartz

Ca-Feldspar

Amphibole

Vermiculite

M AN U

28.70 33.95 28.00 27.66 42.47 62.52 34.62 13.06 23.46 15.54 22.32 43.79 16.20 15.61 18.00 44.00

Clay Minerals Kaolinite Smectite

TE D

---------------------3.40 6.13 ---------------7.00 4.51

Illite

EP

Chlorite

AC C

Coastal Shelf

Main Land

Lakes

IceSheet

Minerals Identified/ Sample No P1 P4 P6 P7 L1 L3 L6 L9 M2 M3 M4 M7 S3 S5 S10 S11

12.70 13.96 11.00 12.86 7.07 ---------7.63 ----------------------

9.60 13.88 11.00 16.08 17.76 ---16.32 13.63 12.27 16.57 12.40 8.64 19.44 16.43 11.00 9.00

M AN U

SC

S H E L F 2 Km

L

P

I C E

Maitri

45'

I C E

TE D

RI PT

Lake Priyadarshini Other lakes 0

L

40'

Shivaling

P O L A R 35'

EP

P L

L

Streaky gneiss Augen gneiss Khondalite & migmatite Garnet-biotite gneiss

30'

Banded gneiss Garnetiferous alaskite

11°25'E

L

50'

11°55'E

Schirmacher Oasis

ANTARCTICA

Novolazarevskay

AC C

70°44'S

70°47'S

46'

45'

ACCEPTED MANUSCRIPT

P5

L8

L9 S10

P3

S4

S5

L7

M4 M1

45'

M2

L2

L1

M7

M6

P8

P6

M5

P4 P2 P1 P7

L5

L6

S9 S11 S12 S13

M3

Shivaling

TE D

M AN U

I

II

III

40'

EP

SC

RI PT I Shelf Ice

35'

II Main rocky land including lakes Land locked lakes Epishelf lakes Proglacial lakes

30'

III Polar Ice Sample location 11°25'E

AC C

70°44'S

45'

70°47'S

46'

ACCEPTED MANUSCRIPT

L3

0

L4

50'

2 Km

S3 S2 S1 S7 S8

S6

11°55'E

ACCEPTED MANUSCRIPT

RI PT

Priyadarshini Lake

A

M AN U

SC

C

A

ICE SHEET

SHELF ICE

B

AC C

EP

TE D

A

D

A