Recent Contribution to the Antarctic Gelology

Abstract

Indian geoscientists have been studying Antarctic geology for three and a half decades in Antarctica. The studies were mainly carried out in campaign mode for long but have now assumed greater focus as these have started investigating scientific questions of global interests. Starting from early report of anorogenic magmatism in the central Dronning Maud Land (cDML), identification and description of magmatic charnockites representing a chemically distinct magma to characterizing and confirming the continuation of East African Orogen in Antarctica. These studies represent some of the key contributions besides providing the baseline geological maps of the cDML area. The establishment of permanent station at the Larsemann Hills has allowed wider India-Antarctica geological correlation.The land-sea-ice interface in the cDML and use of marine sediments as archives of ice-sheet fluctuations as well as providing clues to the sub-ice geology is demonstrated from the Wilkes Land sector in east Antarctica. These ice-sheet proximal deposits allow reconstruction of time-constrained advance and retreat of the east Antarctic ice sheet.The contributions include study of Quaternary deposits, especially the lake deposits which have significant bearing on understanding the ice sheet behavior during late Quaternary. Increasing participation in global scientific programs, multidisciplinary studies and active involvement in Scientific Committee on Antarctic Research (SCAR) specially in geoscience augurs well for future progress of Antarctic geoscience studies in India. IntroductionIndian contribution to the Antarctic Geology has largely been confined to the central Dronning Maud Land (cDML) sector of the east Antarctica for nearly three decades . This was on account of the location of the first two stations, Dakshin Gangotri, located on the ice-shelf and Maitri, the second station on ice free Schirmacher Oasis, from which only limited access was possible. The studies which began as localized geological descriptions have assumed significance lately for two reasons-first recognition of cDML terrain as possible extension of the East African Orogen (EAO) in Antarctica and the significance of sub-ice geology in the context of understanding and predicting East Antarctic Ice Sheet (EAIS) behaviour, the largest single mass of fresh frozen water on planet earth. The studies were extended to the Larsemann Hill sector in eastern Antarctica after 2006,following the identification of site for the Bharati Station in the Grovenes Promontory. Indian contributions to Antarctic geology are described in following description for the three domains, namely, the cDML, the Larsemann Hills and the Wilkes Land sector. Central Dronning Maud Land Sector Geological StudiesThe Wohlthat Massif, a rugged mountainous terrain located ~100km south of the Schirmacher Oasis, exposes large magmatic bodies. Indian geologists in pioneering studies recognized largely anorogenic 270Naresh C Pant et al.nature of this magmatism which ranged from ultrabasic to acidic in co...

Investigations on baseline levels for natural radioactivity in soils, rocks, and lakes of Larsemann Hills in East Antarctica

“…Larsemann Hills are essentially constituted of Granulite facies rocks. Detailed lithological mapping in and around Bharti station revealed occurrence of four major rock types namely pyroxene granulite, garnetiferous granite-granodiorite, sillimanite gneiss, and metapelite (Pant et al, 2017). Representative hand specimen and thin section of the granitic rock samples collected from the Larsemann region are shown in Figs.…”

Advances in Antarctic geoscience studies: Indian contributions

“…Structurally, the NE-SW trending shear zones and mylonites in Schirmacher that show flow planes parallel to the regional foliation of East African Orogeny are believed to have evolved during the late phase of D2/M2 to early D3/ M3 tectonothermal event. Based on the regional setting, the nature and timing of these shear zones and their association with the retrogressive amphibolite facies metamorphism, these zones are suggested to be a part of exhumation (D'Souza et al, 2011;Pant et al, 2017b).…”