Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 An introduction to the crustal evolution of India and Antarctica: the supercontinent connection N. C. PANT1* & S. DASGUPTA2 1Department of Geology, University of Delhi, Delhi 110007, India 2Department of Geography, Jamia Millia Islamia, New Delhi 110 025, India *Correspondence: [email protected] Gold Open Access: This article is published under the terms of the CC-BY 3.0 license. Perhaps the most important advance in our knowl- Several models predict the repeated juxtaposition edge of the Precambrian Earth over the last three of India and Antarctica and subsequent multiple decades has been the general consensus on the disintegrations over a geological period spanning episodic nature of the amalgamation and dispersal .1.5 billion years from the accretion of Columbia of supercontinents (e.g. Rogers 1996; Condie & to the formation of East Gondwana. The big ques- Aster 2010; Nance et al. 2014). The Precambrian tion is how such ‘yo-yo’ tectonics could occur, if history of the Earth is thought to be punctuated by at all. Where, why and when did such repeated inte- the assembly and breakdown of at least three super- grations/disintegrations occur? On an intraconti- continents: Columbia (Nena), Rodinia and Gond- nental scale, how and when were the Proterozoic wana (Fig. 1; e.g. McMenamin & McMenamin mobile belts accreted to the cratons? 1990; Rogers & Santosh 2002; Meert 2012). Convergence of diverse lines of evidence, each Transcontinental correlation in the Precambrian with their own uncertainties, for past intra- and trans- is a complex endeavour requiring multidiscipli- continental correlations, especially in the absence of nary investigations, primarily involving structure/ palaeontological data, is a difficult proposition and tectonics, petrology, geochronology and palaeo- will continue to be debated as more new data are magnetism. A detailed knowledge of all of these generated. disciplines for regions that were supposedly contig- uous as parts of supercontinents is an absolute pri- mary requisite to arrive at any firm conclusion. Rationale for this Special Publication This is the reason why a wide range of disagree- ments exists regarding the exact configurations of There is an increased importance of, and attention the supercontinents, despite the overall consensus paid to, the polar regions, especially Antarctica, on about their existence. Problems are more acute account of the presence of c. 90% of the total fresh- with the older supercontinents, particularly Colum- water of our planet in the East Antarctic Ice Sheet bia and, to some extent, Rodinia. and a projected sea-level rise of c. 60 m if all of Both India and Antarctica are important compo- this melts. In addition, the region acts as a major nents of all three supercontinent configurations, but heat sink because it modulates the ocean circulation their dispositions have been hotly debated (e.g. Rog- and the atmospheric temperature. The sub-ice geol- ers & Santosh 2002; Collins & Pisarevsky 2005; ogy controls this behaviour and major scientific pro- Hou et al. 2008). In particular, two previous Geolog- grammes have been launched to resolve some of ical Society Special Publications (volume 206 these issues, leading to a better definition of the sub- (Yoshida et al. 2003) and volume 383 (Harley ice landscape (e.g. the ADMAP and ICECAP and et al. 2013a)) addressed the many then outstanding ICECAP2 programmes; Bo et al. 2009; Li et al. issues hindering the unambiguous fitting of India 2010; Fretwell et al. 2013). A better understanding and Antarctica into the supercontinent models. of Antarctic history by inferring the sub-ice geology Within each of these continents, the contentious was one of the six priorities identified by the Scien- issue is the identification of terrane boundaries and tific Committee on Antarctic Research (Kennicutt their mutual linkages in the supercontinents et al. 2014). (Fig. 2; Harley et al. 2013b). Extensive isotopic The eastern Gondwana block – consisting of work has revealed the existence of several ter- India, Australia and Antarctica – preserves evi- ranes/domains/provinces, each with distinctive dence of roughly Grenville age orogens, implying geological histories. As a result, no straightforward the existence of simultaneous mountain-building solution is available regarding their correlations. processes in a large continental block. These From:Pant, N.C. & Dasgupta, S. (eds) Crustal Evolution of India and Antarctica: The Supercontinent Connection. Geological Society, London, Special Publications, 457, https://doi.org/10.1144/SP457.14 # 2017 The Author(s). Published by The Geological Society of London. Publishing disclaimer: www.geolsoc.org.uk/pub_ethics Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 N. C. PANT & S. DASGUPTA Fig. 1. Map showing the proposed position of India and Antarctica in archetypal models of Columbia (c. 1.5 Ga), Rodinia (c. 1.0 Ga) and Gondwana (c. 0.5 Ga) supercontinent assembly. Redrawn from Meert (2002); Meert and Torsvik (2003) and Harley et al. (2013b) respectively. orogenic belts preserve evidence of Mesoprotero- Proterozoic and in relation to the presently widely zoic crustal evolution, which can be pieced together separated land masses of India and Antarctica. from currently spatially separated domains to under- This volume presents these studies. stand the subglacial geology of the east Antarctic shield. It is pertinent to quote from the last Special Publication in this context, wherein Harley et al. Organization of this volume (2013b) remarked that: The thirteen papers in this volume are organized into [U]ntil we resolve the subglacial geometry and tectonic two sections. The first section on Antarctic studies setting of the c. 0.5 and 1.0 Ga metamorphism, there contains two papers on the Dronning Maud Land will be no consensus on the configuration of Rodinia, sector in the western part of East Antarctica and or the size and shape of the continents that existed one paper on the rocks from Enderby Land in the immediately before and after this supercontinent. eastern part of this terrain. In proportion to the Some of the contentious issues related to India and exposed terrain and logistic considerations, the sec- Antarctica were discussed and debated at an interna- ond section has ten papers organized into four sec- tional seminar under the aegis of the XIII Interna- tors of the Indian terrain. The first subsection of tional Symposium on Antarctic Earth Sciences in four papers describes the Eastern Ghats Mobile Goa, India in 2015. The presented work and discus- Belt, which is considered to be a geological contin- sions were focused on India- and Antarctica-centric uation of Antarctica. The Chotanagpur Granite studies because both of these constitute key land Gneiss Craton (CGGC), located north of the Singhb- masses for supercontinent reconstructions. It was hum Craton, preserves records of Proterozoic super- realized that there has been significant recent continent activity and two papers illustrate new data regional studies in India with implications for super- from this domain and constitute the second subsec- continent evolution, especially during the tion. Another paper focused further north of the Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 INTRODUCTION Fig. 2. Map showing the locations of the different study areas in India and East Antarctica. Indian tectonic zones redrawn from Ramakrishnan and Vaidyanadhan (2008). East Antarctica in its reconstructed Gondwana context, redrawn from Fitzsimons (2000) and Harley et al. (2013b). CGGC on the South Khasi Hills in the northeastern The outcomes sector of India has been included to describe post-Rodinia thermal activity in the third subsec- Section 1: Antarctica tion. In the next subsection, two papers on the west- ern Indian craton are followed by a paper presenting Mikhalsky et al. (2017) investigate and provide an alternative hypothesis of supercontinent new geochronological data from the Thala Hills amalgamation. area of western Enderby Land, which represents Downloaded from http://sp.lyellcollection.org/ by guest on September 27, 2021 N. C. PANT & S. DASGUPTA a key link between the Indo-Antarctic and Afro- another collisional orogeny related to the amalgam- Antarctic regions. They distinguish three tectono- ation of the Eastern Ghats Belt in Rodinia. magmatic events at c. 980–970, c. 780–720 and c. Using electron back-scattered diffraction and 545–530 Ma. field data, Sawant et al. (2017) interpret an east– Roy et al. (2017) provide a detailed investigation west shear zone between the Eastern Ghats Province of a small nunatak, Baalsrudfjellet, in central Dron- and the Rengali Province as a strike-slip fault juxta- ning Maud Land. They describe a two-stage meta- posing these rocks against Archaean cratonic granu- morphic evolution through the study of granulites lites. The authors correlate this shear zone with at c. 680–660 and c. 580 Ma and provide evidence similar Archaean–Proterozoic intercalations in the for the inland continuation of the extension of East Rauer Group of East Antarctica. African Orogen as the suture between the east and the west Gondwanaland blocks during the Chotanagpur Granite Gneiss Craton. Mukherjee Neoproterozoic. et al. (2017) investigate a variably retrogressed Further west within the east Antarctic shield, granultic orthogneiss and associated lithologies Moabi et al. (2017) describe the Straumsnutane and infer a c. 943 Ma continent–continent collision Formation lavas in western Dronning Maud Land event of the Mesoproterozoic CGGC rocks, linking and compare these with the Espungabera Formation this to the formation of the Rodinia supercontinent. lavas of central Mozambique and the Borgmassivet They suggest the Proterozoic geothermal gradient to intrusions in Dronning Maud Land, Antarctica. be similar to the present day continental geothermal They suggest correlation with the c. 1100 Ma gradient. Umkondo Igneous Province of South Africa. Saikia et al. (2017) describe a volcano- sedimentary sequence, the Bathani sequence, from the northern CGGC and relate it to island arc mag- Section II: India matism.