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The Geological Survey of India , established in 1851, is a government organization in India which is an office attached to the Ministry of Mines of Union Government of India for conducting geological surveys and studies. It is one of the oldest of such organizations in the world and the second oldest survey in the country. The GSI is the prime provider of basic earth science information to the government, industry and the general public, as well as responsive participant in international geoscientific fora. The vibrant steel, coal, metals, cement and power industries. Wikipedia.

Pal T.,Geological Survey of India
Journal of the Geological Society | Year: 2011

The Andaman ophiolite occurs as thrust slices in the outer arc of the Andaman-Java infduction zone. This ophiolite preserves the mantle sequence, layered ultramafic-mafic rocks, intrusive and extrusive rocks. The mantle sequence is represented by serpentinized lherzolite and harzburgite, hosting dunite and chromitite pods. The low Cr-number (0.2-0.4), Cr-number-TiO 2 relation of the chromites, oxygen fugacity (fO 2) values (δlog fO 2(FMQ)=-1.90) and trace elements of mantle peridotites indicate a mid-ocean ridge basalt-suprainfduction-zone (MORB-SSZ) setting. The MORB mantle underwent a low degree of melting (c. 10-15%) and interacted with the infduction-zone melts. Melt-rock interaction of the peridotites in a suprainfduction zone is demonstrated by the replacement of pyroxene grains by olivine grains (Fo90), composition of chromites and oxygen fugacity (δlog fO 2(FMQ)=-1.90 to +2.16, where FMQ is the fayalite-magnetite-quartz buffer). The chromite composition of chromitite pods (Cr-number 0.72-0.75), fO 2 levels and trace elements for layered peridotites, and occurrence of the extrusive rocks as low-Ca boninite and island arc tholeiitic (IAT) basalt indicate interplay of both boninite and IAT melts for the Andaman ophiolite. The MORB mantle of the infducting Indian plate accreted into the mantle wedge and then melting of the accreted mantle produced boninite melt at the first stage and tholeiitic melts at the second stage. © The Geological Society of London.

Mukhopadhyay S.K.,Geological Survey of India
Journal of the Geological Society of India | Year: 2012

Guembelitria is an essential biotic component in the Late Cretaceous-Early Paleogene (K/Pg) marine successions to provide crucial information about the K/Pg boundary; however, it is not well studied in Indian subcontinent. Biostratigraphically well constrained K/Pg successions of Therriaghat and Mahadeo in the East Khasi Hills District, Meghalaya, India provided a scope to present a comprehensive account of the genus in the perspective of differences of opinion about its species. A total of six species including Guembelitria langparensis n. sp., are recognized and their stratigraphic distribution is recorded. A review of the taxonomic validity of the known species, an evaluation of the diverse concepts of Guembelitria cretacea Cushman, and semiquantitative analysis of the recovered species permitted their clustering into two morphogroups that had different ecology. Morphogroup I comprising Guembelitria cretacea, Guembelitria trifolia and Guembelitria langparensis n. sp., is characterized by flared and short spire tests that form a bioseries and thrived as surface floaters. Morphogroup II comprising Guembelitria irregularis, Guembelitria danica and Guembelitria sp a, possesses high spire, narrow tests that have morphological abnormalities and had preference for living in subsurface stressed environment. The occurrence of the species and accompanying other features like ratio of planktonic to benthic foraminifera (p/b), lithologic assemblage and incidence of phosphorite, are used to infer depositional environments and sea level changes during successive biozones of the sequence. The recognized Guembelitria events during the K/Pg transition are discussed with reference to world occurrences. © GEOL. SOC. INDIA.

Bandopadhyay P.C.,Geological Survey of India
Journal of Asian Earth Sciences | Year: 2012

Turbidites composed of sandstone-shale alternations on the Kalipur-Shibpur coast, North Andaman Island, classified under the Palaeocene-Eocene Mithakhari Group in several recent papers are identified as and compared with the type section of the Oligocene Andaman Flysch exposed at Corbyn's Cove, South Andaman Island. The Kalipur turbidites were interpreted as the inner fan and the latter as the distal mid fan facies of a forearc submarine fan. The turbidites of these two locations are separated by ~250. km. Detailed studies concerning the identification and comparison, have however, revealed significant differences, and the turbidite outcrops are not continuous between these two localities.Turbidites at Kalipur-Shibpur and adjacent areas are part of a melange terrane, normally gritty and coarse grained, massive to locally graded bedded, calcareous, intercalated/interstratified with conglomerates and reefoidal limestones and show a framework composition varying from volcanolithic to lithic-poor arkosic sandstones, deposited in several isolated basins, fed by transverse supply of detritus from an accreted and uplifted ophiolite and arc massif. The Kalipur-Shibpur coast exposes marginally deformed, sandstone-dominated turbidites (coherent units) containing abundant ichnotraces, late Palaeocene foraminifera, and rip-up shale clasts, indicating deposition in shallow water accretionary slope basins. South of Kalipur, the Ramnagar coast exposes mud-rich turbidites showing accretion-related deformation. These deformed turbidites are interpreted as offscraped trench deposits. Further south, on the Rampur coast, turbidites intercalated with reefoidal limestones containing late Palaeocene foraminifera indicate deposition on the upper slope or on top of the accretionary slope basin. In contrast classical Bouma sequence-bearing sandstone-shale turbidites at Corbyn's Cove, are part of a continuous outcrop belt of siliciclastic turbidites, lack fossils, carbonate facies and conglomerates, and consist of compositionally uniform greywackes, deposited in an open deep sea fan, fed by axially transported detritus derived from the continental blocks of western Burma.These key differences together with previous mapping and stratigraphic studies confirm the incorrect identification of Andaman Flysch in North Andaman Island in recent papers. The turbidites of these two locations were neither produced by the same sediment gravity flows nor deposited in the same forearc fan during the Oligocene, instead, they were derived from different palaeographic domains, deposited in different tectonic and sedimentary environments and also at different times. This provides new insights into the Paleogene turbidite deposition in this part of Western Sunda Arc. © 2011 Elsevier Ltd.

Radhakrishna T.,Center for Earth Science Studies | Joseph M.,Geological Survey of India
Bulletin of the Geological Society of America | Year: 2012

New geochemical and paleomagnetic results are presented on two Late Cretaceous dikes of the 85-90 Ma leucogabbroic and doleritic dikes and the 65-70 Ma dolerites in Kerala, India. The dikes are rich in incompatible elements, have fractionated patterns with light rare-earth element enrichment and are akin geochemically to Cretaceous basalts on the east coast of Madagascar. The magmas were formed at garnet lherzolite depths above the Marion plume, constituting part of a large igneous province in Madagascar. In contrast, the 65-70 Ma dolerites are moderately depleted in incompatible elements, with almost flat, rare-earth element patterns and resemble the upper formations of the Deccan Traps and the tholeiitic dikes of the Seychelles. These dolerites were formed by melting of spinel lherzolite over the Reunion plume. Paleomagnetic data from the dikes and the other coeval igneous units from south India provide the 90 Ma pole (latitude: 24°; longitude: 293°; A95 = 5.9; N = 18 sites) for India. The 65-70 Ma dolerites possess both normal and reverse polarities, and the mean pole (latitude: 36°; longitude: 283°; A95 = 5.7°; N = 10 sites) compares well with the Deccan superpole. Paleolatitude estimates indicate ~5° southward migration for the Marion plume and a northward migration for the Reunion plume, in conformity with global mantle-circulation models; however, distinguishing migration of the Reunion plume from the effects of true polar wander is difficult. Furthermore, the geodynamic reconstructions extending the shear zones of southern Madagascar into south India are not tenable. © 2012 Geological Society of America.

Mishra O.P.,Disaster Management Center | Mishra O.P.,Geological Survey of India
Bulletin of the Seismological Society of America | Year: 2013

In order to resolve an enigmatic issue relating to the existence of fluidrelated or temperature-related anomalies at the mainshock hypocenter of the 2001 Bhuj, India, earthquake (Mw 7.6), an estimate of the 3D bulk-sound velocity structure is made from the inverted high-quality P- and S-arrival times from a total of 368 aftershocks recorded by 12 temporary seismic stations installed following the 2001 Bhuj earthquake. Results reveal strong lateral and vertical heterogeneity in bulk velocity (Vφ{symbol}) beneath the source zone. The 2001 Bhuj mainshock and its aftershock source zones are associated with anomalously high bulk-sound velocity (high Vφ{symbol}), indicating high bulk elastic strength of the source rocks at the mainshock hypocenter due to high pore pressures of the fully saturated cracked rocks associated with solute precipitation through the processes of acoustic fluidization and cementation. The interpretation of bulk velocity tomograms suggests that the processes of mineral dehydration and permeation of sea/surface water through several active Quaternary faults down to the deep crust might have contributed to in situ fluid-related material heterogeneity in bulk velocity within the fluid-filled fractured rock matrix in the paleorift zone at the 2001 Bhuj mainshock hypocenter, which in turn increased pore pressure, lowered the effective stress, and brought the system into a brittle failure. High Vφ in the intersecting fault geometry in the fractured rock matrix at the mainshock hypocenter can be taken as evidence for the strong role of fluids in association with the intraplate earthquake of the Indian peninsula. © 2013 by the Seismological Society of America.

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