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

T. M. Ganesan ¹

Affiliations
1 Geological Survey of India, IN

Abstract

No Abstract.

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S. V. Srikantia ¹, T. M. Ganesan ¹, P. K. Sinha ¹, B. Tirkey ¹

Affiliations
1 Geological Survey of India, Nilofar Building, Raj Bagh, Srinagar 190008, IN

Abstract

The presence of tourmaline bearing granite clasts in the diamictite of the Thango Formation (Lower Silurian) of the Haimanta Group, in Zanskar Valley of Ladakh, J&K State, suggests the existence of Pre-Silurian tourmaline granite in the Higher Himalaya.

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T. M. Ganesan ¹, J. L. Thussu ²

Affiliations
1 Geological Survey of India, Bhutan Unit,. Chamurchi Post, Jalpaiguri District, West Bengal, IN
2 Geological Survey of India, Bhutan Unit,. Chamurchi Post, Jalpaiguri District, West Bengal., IN

Abstract

The Deoban structural belt of the Tons Valley is lithostratigraphically divided into three Groups-the lower Dharagad Group, the middle Deoban Group and the upper Jaunsar and Simla Groups. The contact between the Dharagad and Deoban Groups is an angular unconformity, while the one between Deoban and Sirnlajfaunsar Groups varies from disconformity to paraconformity. The rocks of the Jaunsar Group are thrust over Deoban and Simla Groups along the south hading Tons thrust.

The Sherar syncline, a prominent, NE-SW trending doubly plunging syncline, affecting the Deoban and Simla Groups and truncated by the northwest trending main Himalayan folds is considered a remnant fold of an earlier orogeny.

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T. M. Ganesan ¹, R. N. Verma ¹

Affiliations
1 Geological Survey of India, Srinagar, IN

Abstract

The Deoban structural belt is a WNW-ESE trending autochthonous belt and exposes some of the oldest sediments of the Lesser Himalaya. The Deoban Group represents a thick pile of carbonate sequence of Riphean age deposited in a stable shelf environment. It is succeeded by the geosynclinal sequence' of the Simla Group in the central and southern parts of the basin. In the northern part it is succeeded paraconformably by eugeosynclinal sediments of the Jaunsar Group comprising argillaceous and argillocalcareous rocks with associated volcanics and lenticular conglomerate and boulder bed at places. The Jaunsar Group is welded to its basement in the northern part, while in the south it rides over the Simle Group (some times the Deoban) which is now marked by the Tons thrust. The Pharat and Bidalna windows expose the Simla Group rocks beneath tbe Chandpur Formation of the Jaunsar Group in a tectonic window of the Krol superficial nappe over the Simla Group

The Shali and the Barahat-Pithoragarh structural belts are the continuation of the Deoban structural belt in the west and east respectively, beneath the veneer of the Jaunsar or the Jaunsar-Jutogh thrust sheets.

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S. V. Srikantia ¹, T. M. Ganesan ², C. Wangdus ²

Affiliations
1 29, J. L. Nehru Road, Calcutta 700 076, IN
2 Nilofar, Rajbagh, Srinagar 190 008, IN

Abstract

The Pangong Tso-Spanggur Tso and the Shyok-Chushul-Dungti are the two tectonic zones in the area north of the Ladakh Range. The former zone has an association of metapelites, metacarbonates and metavolcanics in a graben type basin bounded by granitoids. The latter zone comprises Orbilina limestone, argillite, lava flows and grey-purple conglomerates in another graben type basin bounded on the NE by Pangong Granitoid and on the sw by the Ladakh Granitoid belts. These, along with the Indus Tectonic zone represent NW-SE trending parallel tectonic zones in the Trans-Himalayan Zone. The Pangong Tso-Spanggur Tso appear to be part of the larger Permian basin of Tibet. The Orbiloina limestone-volcanics-conglomerates or the Shyok-Chushul Tectonic Zone are comparable with the Sangeluma belt or the Indus Tectonic Zone. These are independent zones but comtemporaneous in development.

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A. Sahni ¹, S. V. Srikantia ², T. M. Ganesan ³, C. Wangdus ⁴

Affiliations
1 Department of Geology, Punjab University, Chandigarh, IN
2 Department of Geology, 2, Church Street, Bangalore-560 001, IN
3 Department of Geology, Madras, IN
4 Department of Geology, Srinagar, IN

Abstract

A collection of Tertiary fishes and molluscs from the Kuksho Formation of the Indus Group near Nyoma, Ladakh are described, The fish families represented are: Siluridae, Channidae and Cyprinidae. The fishes are associated with dextrally coiled gastropods and unionid pelecypods.

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T. M. Ganesan ¹, K. Gopalakrishnan ¹, R. Renganathan ¹, S. S. Sivasankaran ¹

Affiliations
1 Geological Survey of India, Inner Ring Road, Guindy Industrial Estate, Chennai 600032, IN

Abstract

A sheath fold with inverted hinge is recorded within the charnockite exposed around Nekkanamalai in the Southern Granulite Terrain. The area lies within the NNE-trending Gudiyatham-Bhavani Straight Belt (GBSB) bounded on either side by two distinctly different tectono-stratigraphic terranes brought into juxtaposition along major tectonic contacts. Such folds are known in regions of re-folding, with later folding events of high intensity at high angles to the earlier folds, as well as in shear zones, where the direction of shear is subparallel to the sheath axes. The sheath fold in the area is interpreted to be due to superposed folding resulting from the complicated pattern of deformation produced during the welding of different terranes along the GBSB, which had brought about not only plunge reversals but also plunge inversion of the earlier folds.

Keywords

Structural Geology, Sheath Fold, Granulite Belt, Tamil Nadu.

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