Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

P. L. Narula ¹, Ravi Shanker ¹, S. Chopra ¹

Affiliations
1 Geological Survey of India, IN

Abstract

Chamoli earthquake of 29 March, 1999 (m_b 6.8) has caused extensive damage to life and property. Macroseismic surveys conducted around Chamoli have indicated maximum intensity of VIII on MSK scale. The epicentral tract of this event is oriented in the E-W direction. The aftershocks for the first few days are concentrated in an area of 40 km x 30 km which is bound by MCT in the north and the Alkananda Fault in the south. The authors have suggested a source model of this event on the basis of data generated as well as the seismotectonic setting of the area and have surmised that this event nucleated at the intersection of a transverse fault and the rupture propagated towards west along the detachment surface.

Keywords

Chamoli Earthquake, Seismotectonics, Seismicity in Garhwal, Source Mechanism, Source Dimension, Source Model.

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Ravi Shanker ¹

Affiliations
1 Geological Survey of India, Lucknow, IN

Abstract

No Abstract.

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V. K. Mathur ¹, Ravi Shanker ¹

Affiliations
1 Himalayan Geology Division, Geological Survey of India, Lucknow 226 020, IN

Abstract

Late Precambrian Ediacaran medusoid coelenterates, viz., Tirasiana sp., Medusinites sp, and Beltanella sp. are reported from the upper part of the Krol Formation in the Naini Tal Syncline, Lesser Himalaya in association with other Ediacaran fossils, viz., Beltanelliformis sp., Pteridinium sp, and Ichnogenus Gordia sp.

Keywords

Palaeontology, Krol Formation, Ediacaran Fauna, Naini Tal, Himalaya, Uttar Pradesh.

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Ravi Shanker ¹

Affiliations
1 Geological Survey of India, Lucknow, IN

Abstract

Son-Narbada-Tapti (Sonata) lineament zone - a remarkable megatectonic feature - stradling across Indian Peninsula is a major structural zone, lying between Malwa-Vindhyan Plateau and Ajanta-Buldana-Bastar-Chota Nagpur Plateus, bounded by well defined fault features. It is divisible into several longitudinal fault bound blocks, which are further segmented by number of cross faults into sub-blocks. These blocks have been moving relative to each other right through early Proterozoic to the present. The "Sonata" zone is thermally anomalous with relatively high geothennal gradiants and heat flow. It is also characterised by five layered crustal structure. Thinning of the upper crust, high gravity anomaly, shallowing of the base of magnetic crust, elevated curie-point and solidus of basalt geoisthenns in the axial portion ofthe "Sonata" are very significant features, which support the inference that it is a "mid-continental rift" similar to that of Gregory, Rio-Grande and Red Sea rifts, Rhine graben and Mississipi embaymenL The exposed geological sequences within the "Sonata" rift contain remnants of paleorifting and suturing of Proterozoic times.

Keywords

Narmada-Tapti Lineament; Mid-Continental Rifting; Heat-Flow

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Ravi Shanker ¹

Affiliations
1 Dy. Director General, Geological Survey of India, Lucknow - 226 020, IN

Abstract

No Abstract.

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Ravi Shanker ¹

Affiliations
1 Geological Survey of India, Aliganj, Lucknow-226024, IN

Abstract

No Abstract.

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J. K. Pati ¹, S. Raju ¹, V. D. Mamgain ¹, Ravi Shanker ¹

Affiliations
1 Geological Survey of India (NR), Aliganj, Lucknow-226 024, IN

Abstract

Geological mapping in parts of Bundelkhand Granitoid Complex (BGC) reveals a number of E-W trending shear zones marked by mylonites. Synkinematic fluid activity along these shear zones is conspicuous. Anomalous gold values in the range of 5 and 1000 ppb in BGC is recorded against a background value of l to 2 ppb in most Precambrian granitoids.

Keywords

Economic Geology, Gold, Granites, Precambrian, Bundelkhand, Central India.

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Ravi Shanker ¹, D. D. Bhattacharya ², A. C. Pande ³, V. K. Mathur ²

Affiliations
1 B-5, Sector K, Aliganj, Lucknow 226 024, IN
2 Geological Survey of India, Lucknow, IN
3 Geological Survey of India, Shillong, IN

Abstract

The Ediacaran biota is already known from the Kaurryala Formation (Upper Krol) of Krol Group, Lesser Himalaya, India. The present work records the Ediacaran biota from the underlying Jarashi (Middle Krol=Krol B) and Mahi (Lower Krol=Krol A) Formations. The biota occurs in the intercalated shale-Siltstone sequence deposited in a tidal flat environment. The biota from the Jarashi Formation includes soft-Bodied rmetazoans - Pteridinium sp cf P carolinaense(St Jean) and Charniodiscus sp cf C arboreus Glaessner. The biota of Mahi Formation is represented by Nimbia sp cf N occlusa Fedonkin. In the light of already known Ediacaran biota from the Kauriyala Formation (Upper Krol), this find extends the stratigraphic range of Ediacaran biota in the Krol Belt downward. The present biota is comparable with Late Neoproterozoic Ediacaran biota of Russian Platform, South Australia, Namibia, North Carolina and Canada N occlusa Fedonkin has also been recorded from the Cambrian rocks of Arctic Norway and Ireland.

Keywords

Ediacaran Biota, Krol Group, Jarashi Formation, Mahi Formation, Lesser Himalaya.

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Ravi Shanker ¹, S. Nag ², S. Shome ¹

Affiliations
1 Geological Survey of India, Kolkata, IN
2 Geological Survey of India, Lucknow, IN

Abstract

Mesoproterozoic metavolcano-sedimentary sequence in and around Bhowali-Khairna area, Uttaranchal, constitute mostly metabasalts with quartzites, phyllites and variegated slates, referable to Bhimtal Formation. Our study was centred on metabasalts and the rocks occurring in close spatial association with them. Detailed petro-mineralogical and SEM-EDS studies have revealecl the presence of gold which we report here for the first time. Of the two types of metabasalts viz., massive, crudely foliated type and foliated type, both showing mineralogical assemblages of subgreenschist facies and greenschist facies respectively, gold is commonly found in the foliated type and rarely in the massive type. Presence of gold as tiny grains in disseminated fashion suggest that widespread hydrothermal activity caused precipitation of gold after the rocks had witnessed peak metamorphism.

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Ravi Shanker ¹, Prabhas Pande ²

Affiliations
1 Geological Survey of India, Jawaharlal Nehru Road, Kolkata - 70001 6, IN
2 Geological Survey of India, Earthquake Studies Unit, Sector-E, Aliganj, Lucknow - 226024, IN

Abstract

Extensive geoseismological studies of the 26 January 2001 Kutch earthquake have been carried out by Geological Survey of India in an area of 1.2 million sq km. The isoseismal map of the earthquake has been prepared adopting MSK-64 Intensity Scale. Separate studies have been conducted for evaluating the effects of the earthquake on engineered structures, geothermal manifestations and groundwater. A 13-Station MEQ array, in operation for the last two and a half months in the Kutch region, has precisely delineated the aftershock activity. Collation and analysis of data obtained from different sources have enabled understanding of source mechanism of the seismic event.

Keywords

Earthquake, Isoseismal, Intensity, Liquefaction, Coseismic Deformation, Bhuj, Kutch, Gujarat.

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Ravi Shanker ¹, T. Pal ¹, P. K. Mukherjee ¹, S. Shome ¹, S. Sengupta ¹

Affiliations
1 Geological Survey of India, Kolkata - 700 016, IN

Abstract

No Abstract.

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V. K. Mathur ¹, Ravi Shanker ¹

Affiliations
1 Himalayan Geology Division, Geological Survey of India, Lucknow, IN

Abstract

The paper records the discovery of Ediacaran fossils, viz., Beltaneliformis sp. cf. B. brunsae Menner, Pteridinium sp. cf. P. simplex Gurich and Ichnogenus Gordia sp. cf. G. marina Emmons from the upper part of the Krol Formation in the Naini Tal Syncline, Lesser Himalaya. These taxa are comparable with the fossils present in the late Precambrian Wernecke assemblage of Canada and Ediacaran assemblage of other areas, particularly Australia and Eurasia.

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R. K. Bandyopadhyay ¹, Ravi Shanker ²

Affiliations
1 Project Arsenic, Eastern Region, G.S.I., Salt Lake, Sector-2, Kolkata - 700 091, IN
2 B-5, Section-K, Aliganj, Lucknow - 226 024, IN

Abstract

No Abstract.

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