U-Pb geochronology and structural geology across major shear zones of the Southern granulite terrain of India and organic carbon isotope stratigraphy of the Gondwana coal basins of India : their implications for Gondwana studies
Doctoral Thesis
1998
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University of Cape Town
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Abstract
This thesis is divided into 2 parts. The first part (Chapters 1-5) concentrates on unravelling the . Precambrian geological history of the high-grade poly-metamorphic and poly-deformed basement of southernmost India, using field geology and U-Pb geochronology. Because Peninsular India occupied a central position in Gondwana, this work bears on reconstruction models of central Gondwana between circa 600 Ma and 200 :f1,a. The second part of the thesis (Chapter 6) tests the use of organic carbon isotopes as a chemostratigraphic tool to correlate between the lower part of terrestrial Gondwana (Upper Carboniferous to Triassic) sequences in India. This work contributes to (i) intra-basinal and inter-basinal stratigraphic correlation and carbon isotope variations during the Pennian-Triassic extinction event of Gondwana; and (ii) refines the inter-continental correlations of the Gondwana type sequences in India with those in South Africa and Madagascar. This century much attention has been focused on the reconstruction of Gondwana, and as a result, the broad relative positions of different Gondwana fragments and their later dispersal histories is now well understood. Finer-scale reconstructions, based on modern geochronological and isotope studies integrated with field studies of continental rocks, are still needed to resolve the detailed kinematic histories of continental break-up and the evolution of continental lithosphere in general. Shear zones that cross the boundaries of continental fragments provide 'piercing points' in fitting the fragments back together. To realize this, the kinematics and the timing of major shear zones need to be determined. The first part of this thesis, therefore, primarily focuses on understanding the kinematics and geochronology of a number of subvertical continental scale shear zones in the Southern Granulite Terrain of India (SGT).
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Bibliography: p. 277-308.
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Ghosh, J. 1998. U-Pb geochronology and structural geology across major shear zones of the Southern granulite terrain of India and organic carbon isotope stratigraphy of the Gondwana coal basins of India : their implications for Gondwana studies. University of Cape Town.