A B C D E F G H I J K L M N O P Q R S T U V W X Y Z All
Pandit, S. A.
- The Application of Hydrogeochemical Method in Uranium Exploration - A Case Study from Barabazar-Manbazar Area, Purulia District, West Bengal
Authors
1 Atomic Minerals Directorate for Exploration and Research, Jamshedpur-831002, IN
2 Atomic Minerals Directorate for Exploration and Research, Hyderabad-500016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 72, No 4 (2008), Pagination: 561-570Abstract
Hydrogeochemical exploration were earned out over an area of 700 sq km in Barabazar-Manbazar area of Purulia district, West Bengal, in order to identify target areas for the uranium mineralization. Water samples were collected from 504 borewells in the Singhbhum Group meta-Sediments and Chhotanagpur Granite Gneissic Complex (CGGC) including South Purulia Shear Zone (SPSZ). For individual Iithological domains, univariate and multivariate statistical techniques were applied to the analytical data on 10 variables, i.e. U, Na+, K+ , Mg+2, Ca+2, SO4-2, HCO3, Cl-, conductivity and pH. Five hydro uranium anomalous zones withm CGGC were delineated at Raghunathpur, Tentla, Chepua-Dighi, Ban and Jitujon areas. However, distinct pattern of high uranium values along with uranium/Conductivity are observed only in Raghunathpur-Tentla and Chepua-Dighi areas in the proximal tectonized zones of SPSZ. Based on the distinctive hydrogeochemical attributes, and favourable geology and structure, the areas in the vicinity of Raghunathpur-Tentla and Chepua-Dighi in the northern proximal contact of SPSZ, are designated as potential target areas for detailed geological and geophysical exploration.Keywords
Hydrogeochemistry, Uranium, SPSZ, CGGC, Singhbhum Group, Purulia, West Bengal.
- Uranium Mineralisation in the Neoproterozoic Bhima Basin at Gogi and near Ukinal: an Ore Petrological Study
Authors
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 01 6, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Bangalore - 560 072, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 59, No 4 (2002), Pagination: 299-321Abstract
Uranium mineralisation in the Neoproterozoic Bhima basin todate has been found near Ukinal and at Gogi. U-mineralised phosphatic horizon near Ukinal includes the lithounits of phosphatic micritic limestonelchert and siliceous, calcareous phosphorite, some of which are manganiferous and glauconite-bearing. Uranium in these phosphatic rocks, correlatable with P2O5content (r>0.9), occurs mostly in collophanc and is difficult to extract. This mineralisation is sedimentary-diagenetic.Mineralisation at Gogi is more promising. This occurs within the major E-W trending Gogi-Kurlagere fault, near to its intersection with a NE-SW trending fault and is hosted by both brecciated, siliceous limestone and deformed basement rock represented by low-Ca biotite granite-granodiorite. Over 80% of the mineralisation at Gogi occurs as veins, veinlets and fracture-fills, composed of coffinite, lesser pitchblende, accessory U-Ti-Si complex (only in granitoid), associated intimately with reductants like sulphides and organic matter, and also clays (illite, smectite). Pitchblende is of two generations, both replaced by and replacing coffinite, and these two U-minerals, in turn, arc replaced by U-Ti-Si complex. The U-minerals occurring in limestone are Th-poor and are characterised by variable contents of U, Pb, Si and lanthanides (LREE>HREE), and as compared to those in granitoid are marked by higher contents of U, Pb, Fe and lower contents of Si and lanthanides. Amongst the sulphides, pyrite is predominant and occurs in three modes, viz., coarse euhedral-subhedral, framboidal and reticulate. The rest comprise marcasitc, chalcopyrite and galena in accessory to minor amount. These sulphides carry notable contents of Co, Ni, Se As, Ag and Au, with enrichment of Ag, Co, Ni in chalcopyrite followed by pyrite (more in framboidal type), Se in galena and Au more in sulphides from the granitoid. These high-value metals can be recovered as by-products during extraction of U. The organic n~atteris heterogenous and contains U, Si, Ca, Al, Pb and Fe, with the one rich in U is also high in the other elements. Radioactive clay contains U, P and REE. Both radioactive organic matter and clay are almost free of Th and Zr, with LREE>HREE. Paragenetically, the uranium minerals were formed later than the sulphides and organic matter. U-mineralisation at Gogi is poly-phase and poly-metallic, hydrothermal vein type with an Eh of -0.2 to -0.3V, pH of 7 to 8, and temperature of <200°C. The controls for this U-mineralisation are: (a) fertile granitoid as source, (b) structurally weak and permeable zones of faults, folds, brittle-ductile deformation and unconformity, along basin margin, (c) presence of strong reductants of organic matter and sulphides, (d) impervious and reactive cover rock of limestone and (e) dyke activity in the basement which may have acted as heat source and created necessary geothermal gradient for remobilisation and precipitation of U. These can be taken as guides for U-exploration in similar geologic set-up.
Keywords
U-Mineralisation, Hydrothermal, Neoproterozoic, Bhima Basin, Gogi, Ukinal, Karnataka.- Radioactive Quartz-Pebble Conglomerates from Western Margin of Bonai Granite Pluton, Sundargarh District, Orissa - A New Find
Authors
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Khasmahal, Jamshedpur - 831 002, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 73, No 4 (2009), Pagination: 537-542Abstract
Several radioactive quartz-pebble conglomerate (QPC) occurrences at the western margin of Archaean Bonai granite and overlying Iron Ore Group (IOG) rocks have recently been located over a total strike length of 8-10 km intermittently in a NE-SW to E-W trend with steep dips due north- west to north in parts of Sundargarh district of Orissa. The QPC samples have analysed up to 0.039% U3O8 and 0.035% ThO2 with high concentration of Y (74 to 518 ppm), La (<100 to 880 ppm), Cr (126 to 633 ppm), Zr (137 to 1250 ppm) and Pb (31 to 581 ppm). Cellulose Nitrate (CN) film studies of few QPC samples indicated adsorbed uranium over goethite and infiltrated ferruginous material (limonite), secondary uranium as encrustation and fracture filling and discrete sub-rounded grains of monazite, zircon, allanite and rare xenotime in the matrix of QPC as radioactive phases. Higher content of Th over U, elevated concentration of Y and La in QPC eliminates the possibility of its low temperature product by epigenetic processes. Poor correlation of U with elements like Pb, Y, Zr, La and Cr can be explained due to surficial leaching of uranium from QPC after its deposition as reflected by adsorbed U over iron- oxides and low U/Th ratio in QPC in the area.Keywords
Quartz-Pebble Conglomerate, Bonai Granite, Radioactive Minerals, Orissa.References
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