Shear zones in the boundary between Eastern Ghats Province (EGP) and the cratons of Singhbhum in the north and Bastar in the west provide an excellent opportunity to study the tectonics of shear zone development and i...Shear zones in the boundary between Eastern Ghats Province (EGP) and the cratons of Singhbhum in the north and Bastar in the west provide an excellent opportunity to study the tectonics of shear zone development and its timing in relation to the evolutionary history of the granulite suites. Detailed structural, microfabric and quartz C-axis patterns revealed a high temperature shear zone, at the western boundary between EGP and Bastar Craton (BC) around Paikmal. Petrological studies in this shear zone indicated decompression coeval with stretching in the sheared granulites. Geochronological constraints provided here indicate rapid exhumation of deep seated granulites in this boundary shear zone;the timing also is late in relation to the long-lived thermal (granulite formation) event in the EGP. Additionally, our geochronological data demonstrated the ~1600 Ma event in the Eastern Ghats Belt (EGB) involving sedimentation, magmatism, metamorphism and crustal anatexis, as a significant world event.展开更多
The Southern Granulite Terrane(Dharwar Craton),South India,is a key unit for understanding the origin of charnockite.New U-Pb and Lu-Hf analyses in zircon crys-tals from 16 samples representing a wide variety of litho...The Southern Granulite Terrane(Dharwar Craton),South India,is a key unit for understanding the origin of charnockite.New U-Pb and Lu-Hf analyses in zircon crys-tals from 16 samples representing a wide variety of litho-types from the quarries in Kabbaldurga reveal a complex geological history in the Archean and early Paleoprotero-zoic.Magmatic protoliths predominantly record Paleoar-chean ages between 3.4 and 3.2 Ga.Combined U-Pb and Lu-Hf signatures indicate a history of recurrent crustal anatexis,juvenile magmatic input,and felsic injections.Mesoarchaean magmatic charnockites were generated mainly from hornblende-dehydration melting of Paleoar-chaean mafic rocks.In addition,Peninsular Gneissic Com-plex of the Dharwar Craton,commonly described as TTG suites,are likely generated by melting of hydrated basalt.The new data are consistent with the idea of a convecting magmatic cycle and also support the proposal that the southern Dharwar Craton comprises a tilted cross-sec-tion through the Archaean crust.Paleoproterozoic high-temperature event is documented here as a complex unit involving juvenile mafic magmatism,granulite facies imprints and crustal anatexis as well as felsic injections,occurring within a short time period around 2.5 Ga.展开更多
文摘Shear zones in the boundary between Eastern Ghats Province (EGP) and the cratons of Singhbhum in the north and Bastar in the west provide an excellent opportunity to study the tectonics of shear zone development and its timing in relation to the evolutionary history of the granulite suites. Detailed structural, microfabric and quartz C-axis patterns revealed a high temperature shear zone, at the western boundary between EGP and Bastar Craton (BC) around Paikmal. Petrological studies in this shear zone indicated decompression coeval with stretching in the sheared granulites. Geochronological constraints provided here indicate rapid exhumation of deep seated granulites in this boundary shear zone;the timing also is late in relation to the long-lived thermal (granulite formation) event in the EGP. Additionally, our geochronological data demonstrated the ~1600 Ma event in the Eastern Ghats Belt (EGB) involving sedimentation, magmatism, metamorphism and crustal anatexis, as a significant world event.
基金funded by the India-Brazil bilateral co-operation Project:INT/BRAZIL/P-02/2013by Indian Statistical Institute,Geoscience Institute of São Paulo University,Brazil and Department of Geology,University of Calcutta.M.Hueck thanks FAPESP for a post-doctoral fellowship(grant 2019/06838-2).
文摘The Southern Granulite Terrane(Dharwar Craton),South India,is a key unit for understanding the origin of charnockite.New U-Pb and Lu-Hf analyses in zircon crys-tals from 16 samples representing a wide variety of litho-types from the quarries in Kabbaldurga reveal a complex geological history in the Archean and early Paleoprotero-zoic.Magmatic protoliths predominantly record Paleoar-chean ages between 3.4 and 3.2 Ga.Combined U-Pb and Lu-Hf signatures indicate a history of recurrent crustal anatexis,juvenile magmatic input,and felsic injections.Mesoarchaean magmatic charnockites were generated mainly from hornblende-dehydration melting of Paleoar-chaean mafic rocks.In addition,Peninsular Gneissic Com-plex of the Dharwar Craton,commonly described as TTG suites,are likely generated by melting of hydrated basalt.The new data are consistent with the idea of a convecting magmatic cycle and also support the proposal that the southern Dharwar Craton comprises a tilted cross-sec-tion through the Archaean crust.Paleoproterozoic high-temperature event is documented here as a complex unit involving juvenile mafic magmatism,granulite facies imprints and crustal anatexis as well as felsic injections,occurring within a short time period around 2.5 Ga.
