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Kaul, Ravi
- Characterization of Extractable Uranium in Domiasiat Sandstones, West Khasi Hills District, Meghalaya
Authors
1 Atomic Minerals Division, Begumpet, Hyderabad 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 40, No 1 (1992), Pagination: 76-78Abstract
Uranium mineralisation in Domiasiat sandstone is due to migration and fixation by biogenic processes, and leaching and redistribution by surface and groundwater. Fine-sized pitchblende and coffinite are associated with carbonaceous matter and pyrite. Characterization of the extractable uranium indicates that its nature varies from sample to sample and appears to be dependent on pH, Eh and the amount of soluble sulphates in them and to some extent on gangue minerals like calcite which can neutralise the acid component. It is inferred that alteration of sulphides and formation of sulphates results in an acidic condition favouring mobilisation.Keywords
Uranium, Khasi Hills, Meghalaya.
- Uranium Mineralization in the Siwaliks of Northwestern Himalaya, India
Authors
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
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 41, No 3 (1993), Pagination: 243-258Abstract
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.