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

Ravi Kaul ¹, K. Umamaheswar ¹, S. Chandrasekaran ¹, R. D. Deshmukh ¹, B. M. Swarnkar ²

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, AMD Complex, Begumpet, Hyderabad 500 016, IN
2 Atomic Minerals Division, Department of Atomic Energy, Uniara Gardens, Jawaharlal Nehru Road, Jaipur 302 004, IN

Abstract

The Siwalik Group constituting about 6000m of fluvial sedimentary rocks of Middle Miocene to Pleistocene age has been under exploration for uranium over the last two decades using different techniques including exploratory drilling, mining. More than 350 uranium occurrences forming eight major clusters between Poonch (Jammu, Kashmir) in the west and Tanakpur (Uttar Pradesh) in the east have been identified. A majority of these occurrences are confined to three distinct stratigraphic horizons: (1) lower part of Upper Siwaliks corresponding to the upper part of Garchandi energy sequence; (2) upper part of Middle Siwaliks (the middle part of Garchandi energy sequence); and (3) upper part of Lower Siwaliks (Jwalamukhi energy sequence).

Uranium mineralization occurs as small peneconcordant lensoid bodies with the longer dimension of individual lenses traceable from a few tens of metres to 700m, sub-parallel to strike or dip. The average grade of different occurrences in Siwaliks varies from 0.02-0.06% U₃O₈ and thickness less than a metre to 4m. Uraninite, pitchblende, coffinite, and a variety of secondary uranium minerals including tyuyamunite, uranophane, bayleyite, andersonite, schoepite, liebigite, swarlzite, and schroeckingerite have been identified. Azurite and malachite are also associated in some of the uranium occurrences in Lower Siwaliks. The sedimentological, geochrmical, and tectonic attributes of the Siwaliks indicate a sedimentary uranium province.

Uranium mineralization in Siwaliks is attributed to concentration of intrinsic uranium in the sediments derived from fertile Himalayan provenance and subsequent remobilisation by groundwater. Enrichment of uranium is controlled by sedimentary and lithological characteristics such as porosity-permeability barriers and abundance of reductants such as organic carbon, pyrite, and anaerobic bacteria. A secondary control by faults has also been observed at some places. Relatively higher concentrations of Se, Mo, Cu, Co, V, and Au have been noted in some of the uraniferous zones.

Keywords

Uranium Mineralization, Siwalik Group, North-Western Himalayas.

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Mithilesh Sharma ¹, T. P. S. Rawat ¹, Y. C. Sharma ², B. M. Swarnkar ¹, Jagmer Singh ³

Affiliations
1 Department of Atomic Energy, AMD, New Delhi - 110 066, IN
2 40312, Chand Nagar, New Delhi - 1 10 018, IN
3 407, Pacific Apartment, X/39, Dwarka, New Delhi - 110 045, IN

Abstract

Ground radiometric survey carried out in the early Tertiary Dagshai-Kasauli Formations in the northwestern foothill Himalaya has led to the discovery of uranium mineralised sandstone bands extending for about (a) 500 m, with 5-10 m width, at Tarol, 8 km southwest of Solan and (b) 250 m, with 4-7 m width, at Maltu, 6.5 km southwest of Solan, in the Solan district of Himachal Pradesh. Grab samples from (a) Tarol assayed up to 1.41% eU₃O₈, 1.65% U₃O₈ (β/γ) and <0.005% Tho₂ and (b) Maltu assayed up to 0.24% eU₃O₈, 0.28% U₃O₈ (β/γ) and 2. In both the localities, majority of the samples show disequilibrium in favour of parent (uranium). Uraninite and uranophane are the main uranium minerals, which occur in close association with disseminated pellets of organic matter.

Keywords

Economic Geology, U-Mineralisation, Sandstone Type, Tertiary, Dharamsala, Solan, Himachal Pradesh.

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