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

A. V. Subrahmanyam ¹, Jagmer Singh ²

Affiliations
1 RCER, AMD, (P.O), Assam Rifles, Shillong - 793011, IN
2 1-10-153/156, AMD, Begumpet, Hyderabad - 500 016, IN

Abstract

The geochemistry reveals LREE enrichment, high degree of fractionation, positive Ce anomalies and negative Eu anomalies in the samples. Red mud contains 18 to 29% of heavy minerals; and thus the red mud could be an alternative source to beach sands.

Keywords

Economic Geology, REE, Bauxite, Heavy Minerals, Orissa.

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A. V. Subrahmanyam ¹, L. Siddiram Reddy ¹

Affiliations
1 AMDER, 1-10-156, AMD Complex, Begumpet, Hyderabad - 500 016, IN

Abstract

Molybdenite occurs as veins and fracture fillings in the crystalline limestone patches that occur with in quartzite of Ghansali Formation at Thayeli area in the Bhillangana valley, Tehri district. The limestone contains anomalous quantities of trace elements like Ba, Sr, Cu, Mo, U and Th. The mineralogy, trace element chemistry and geological setting of the crystalline limestone patches reveal that the limestone has under gone contact metamorphism into a skarn due to intrusion of the chirpatiyakhal granite.

Keywords

Molybdenite, Crystalline Limestone, Skarn, Uttaranchal.

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H. K. Sabot ¹, A. V. Subrahmanyam ², S. Nayak ²

Affiliations
1 AMD Complex, Hyderabad - 500 016, IN
2 AMD ER/DAE, Hyderabad - 500 016, IN

Abstract

No Abstract.

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A. V. Subrahmanyam ¹, K. K. Sinha ², A. K. Bagchi ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, IN
2 Atomic Minerals Directorate for Exploration and Research, Nongmynsong, PO Assam Rifles, Shillong-793 001, IN

Abstract

No Abstract.

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S. C. Patel ¹, A. V. Subrahmanyam ², T. Desapathi ², M. Nageswara Rao ², Y. V. Rathaiah ², V. Anil Kumar ², D. Rajasekhara Reddy ³, Malathi Vemuri ³

Affiliations
1 Department of Earth Sciences, IIT, Powai, Mumbai - 400 076, IN
2 Atomic Mineral Directorate for Exploration and Research, Begumpet, Hyderabad - 560 016, IN
3 Department of Geology, Andhra University, Visakhapatnam - 530 003, IN

Abstract

No Abstract.

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S. N. Kak ¹, A. V. Subrahmanyam ¹, S. Nag ², T. Pal ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad - 500 016, IN
2 Geological Survey of India, Sector E, Aliganj, Lucknow-226024, IN
3 Geological Survey of India, Kolkata, IN

Abstract

No Abstract.

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S. N. Kak ¹, A. V. Subrahmanyam ¹

Affiliations
1 1 - 10- 15311 56, AMD Complex, Begumpet, Hyderabad - 500 016, IN

Abstract

Depositional conditions deduced from field, petrography and textural studies show that Lower Mahadek sediments (LMS) are of fluvial and Upper Mahadek sediments (UMS) are of marine origin. A hard lateritic ground represents the discontinuity surface between the fluvial, reduced uranium-mineralized facies (LMS) and the marine, oxidized facies (UMS). The change in facies, together with the pyroclastics discovered recently, represents a distinct time gap within the Mahadek sedimentation not reported earlier and is related to Sylhet volcanism. The pyroclastics and discontinuity surface indicate that the Lower Mahadek sediments may range from late Jurassic to early Cretaceous and Upper Mahadek sediments are most probably late Cretaceous, the intervening period being represented by the deposition and denudation of pyroclastics. This study shows that the Lower Mahadek are volcanoclastic sediments and brings out an unconformity within the Mahadek Formation of Meghalaya plateau.

Keywords

Discontinuity Surface, Pyroclastics, Mahadek Formation, Meghalaya.

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