Journal ArticleDOI
Ancient crustal metamorphism at low p H 2 O :charnockite formation at Kabbaldurga, south India
TLDR
Arrested charnockitic conversion of amphibolitic gneiss at Kabbaldurga, Karnataka State, south India, was studied mineralogically.Abstract:
Arrested charnockitic conversion of amphibolitic gneiss at Kabbaldurga, Karnataka State, south India, was studied mineralogically. Iron-rich pyroxenes were generated from amphibole in patches and stringers without melting. The dark colour of charnockite arises from numerous tiny veins of chlorite and manganese-bearing calcite, particularly in feldspars. The metamorphism was effected by very local, mainly grain-boundary, migration of volatiles low in H2O, and probably dominantly CO2. This was followed by vein alteration at lower temperatures from volatiles richer in H2O. The volatiles are ascribed to massive liberation from the mantle in upwelling areas, and this may have been an important process in the evolution of the deep continental crust.read more
Citations
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Carbonic metamorphism, granulites and crustal growth
TL;DR: The hot-spot and plate-tectonic models of Precambrian crustal evolution lead to different schemes for CO2 delivery to continental roots as mentioned in this paper, and new tectonic concepts may be needed to explain carbonic metamorphism, minor-element depletions, and local phenomena of arrested development of charnockite in terrains.
Journal ArticleDOI
Precambrian Tectonics and Crustal Evolution in South India
TL;DR: In this paper, it was shown that a large N-S strike-slip shear belt was formed by a plate tectonic and thermal event that purged the deep crust of H₂O to form granulites.
Journal ArticleDOI
The transformation of amphibolite facies gneiss to charnockite in southern Karnataka and northern Tamil Nadu, India
TL;DR: In this paper, Petrologic investigations in the transitional zone south of Mysore have established the following points:============ ✓ ✓ ✓ • ✓ ✓• ✓ • • ✓• • • • · • •• •• The transition from the metamorphic grade to the granulite grade is prograde.
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Age and tectonic evolution of Neoproterozoic ductile shear zones in the Southern Granulite Terrain of India, with implications for Gondwana studies
TL;DR: In this article, the authors present new geochronological and structural data that indicate a continuation of the Dharwar Craton into the Southern Granulite Terrain as far south as a newly identified Neoproterozoic shear zone, here named the Karur-Kamban-Painavu-Trichur Shear Zone (KKPTSZ).
Journal ArticleDOI
The tectonic framework of the South Indian craton: A reconnaissance involving LANDSAT imagery
S. A. Drury,R.W. Holt +1 more
TL;DR: In this article, a 1:1,000,000 scale LANDSAT imagery and reconnaissance structural analysis has revealed a pattern of tectonic evolution in the South Indian craton extending from Archaean times to the late Proterozoic.
References
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Journal ArticleDOI
The evolution of the earth's crust: Modern plate tectonics to ancient hot spot tectonics?
TL;DR: In this article, it is suggested that massive mixing processes occur near the base of the continental crust when mantle magmas are ponded near the Moho interface and this process is responsible for the general geochemistry of granitic magmas.
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Geochemistry of Granulite Facies Rocks and Problems of their Origin
TL;DR: The author’s opinion the important problem associated with granulite facies rocks is not that of their origin, but rather of their importance as constituents of the continental crust, and how they attained their present chemistry.