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Verma, M. B.
- Uranium and Polymetallic Sulphide Mineralisation in the Banded Iron Formation at Udaisagar, Udaipur District, Rajasthan
Authors
1 Atomic Minerals Directorate For Exploration and Research, Department of Atomic Energy, Hyderabad - 500016, IN
2 Atomic Minerals Directorate For Exploration and Research, Department of Atomic Energy, Jaipur - 302018, IN
3 Atomic Minerals Directorate For Exploration and Research, Department of Atomic Energy, Nagpur - 440 001, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 61, No 6 (2003), Pagination: 703-710Abstract
Thmly laminated, pelagic, Banded Iron Formation (BIF) of Lower Proterozoic Aravalli Supergroup lies close to basement granite and phyllites over a stretch of 5 km along the Udaisagar-Kalamagra tract, Udaipur district, Rajasthan. BIF is characterised by rhythmic stratification of meso- and micro-bands of iron oxides with light coloured bands of silica/chert. Banded Haematite Quartzite (BHQ), a part of BIF, is 5-30 m in width and is intercalated with carbonaceous shale/phyllites. Primary sedimentary structures, viz., bedding, banding, laminations, convolute lammations and synsedimentary breccia and faults, coupled with low value for Co/Ni (0.18; n = 7) suggest its deposition as chemogenic sediment in a calm, tranquil and deep-sea environment.BIF analysed on an average (n=5) 35.81 % Fe2O3 and 34.5% Si02 with enrichment in sulphides and uranium (138 ppm). Correlation matrix shows strong positive correlation between uranium and copper (r = 0.80) and negative correlation of U with V, Ni, Co and Mo. Uranium content varies from 100 to 470 ppm (n = 37) and appears to be in adsorbed state on ferric oxide. Field relationship, coupled with ternary plots of Al2O3 - (CaO + MgO) - SiO2, Fe2O3 - (CaO+MgO) - SiO2 and Eu/Sm ratio (av. 0.275; n = 10) confirms its Proterozoic age. BIF exposed at Udaisagar-Kalamagra tract forms a linear belt and resembles the early Proterozoic Lake Superior type in its geochemical signatures.
Keywords
Geochemistry, BIF, Uranium, Base Metal Sulphides, Aravalli Supergroup, Udaisagar, Rajasthan.
- Geochemical Assessment of Groundwater Around Macherla- Karempudi Area, Guntur District, Andhra Pradesh
Authors
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Begumpet, Hyderabad - 500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 73, No 2 (2009), Pagination: 202-212Abstract
Groundwater in Palnad sub-basin is alkaline in nature and Na+-Cl--HCO-3 type around Macherla–Karempudi area in Guntur district, Andhra Pradesh. Total dissolved solids (TDS) show strong positive correlation with Cl-, Na+, Ca2+ and Mg2+, and positive correlation with SO2-4, K+ and HCO-3. Calcareous Narji Formation is the dominant aquifer lithology, and water-rock interaction controls the groundwater chemistry of the area. Chloro-alkaline indices (CAI) are positive at Miriyala, Adigopula, Mutukuru, Macherla and Durgi suggesting replacement of Na+ and K+ ions from water by Mg++ and Ca++ ions from country rock through base exchange reactions. Negative CAI values are recorded at Terala, Rayavaram and Nehrunagar, which indicate exchange of Na+ and K+ from the rock as cation-anion exchange reaction (chloro-alkaline disequilibrium).
TDS range from 91 to 7100 ppm (Avg. 835 ppm) and exceed the prescribed limit of drinking water around Mutukuru, Durgi, Rayavaram, Khambampadu and Ammanizamalmadaka areas. Scanty rainfall and insufficient groundwater recharge are the prime factors responsible for high salinity in the area. Fluoride content ranges from <1 to 3.8 ppm and contaminated areas were identified around Macherla (1 sq km; 3.8ppm), Mandadi (1 sq km, 2.1ppm) and Adigopula (2 sq km, <1 to 3.7 ppm). The % Na+ content varies from 17 to 85 with the mean value of 57, and eighty (80) samples showed higher %Na+ in comparison to the prescribed limit of 60 for irrigation water. Sodium Adsorption Ratio (SAR) and % Na+ in relation to total salt concentration indicate that groundwater (51%) mostly falls under doubtful to poor quality for irrigation purpose. Groundwater of Adigopula village is fluoride contaminated and remedial measures are suggested to improve the water quality.
Keywords
Chloroalkaline Indices (CAI), Potability, Total Dissolved Solids (TDS), Fluoride, Sodium Absorption Ratio (SAR), Macherla-Karempudi, Andhra Pradesh.- Hydrouranium Anomalies as an Effective Tool in Exploration of Concealed Unconformity Related U-Deposit in Srisailam Subbasin, Andhra Pradesh - Case Study from Chitrial Area
Authors
1 Atomic Minerals Directorate for Exploration and Research, Bangalore-560 072, IN
2 Atomic Minerals Directorate for Exploration and Research, Hyderabad -500 016, IN
Source
Journal of Geological Society of India (Online archive from Vol 1 to Vol 78), Vol 78, No 5 (2011), Pagination: 468-476Abstract
Relationship of hydro-uranium anomalies (2-649 ppb) vis-a-vis underlying uranium ore body has been attempted based on seventy nine water samples collected from the exploratory boreholes on the northern periphery of Srisailam sub basin, Nalgonda district, A.P. Water table is hosted in the granitoid aquifer which underlies the cover rocks of Srisailam Formation. TDS (total dissolved salt) range from 123 to 1088 ppm (x- = 329 ppm) and analyzed >500 ppm in eight samples. Water samples show a strong positive correlation of TDS with Cl- (r=0.90), Na+ (r=0.82), Mg (r=0.80) and a moderate positive correlation with Sr (r=0.48) and Ca (r=0.70). Low value (<0.4) of Normalised Magnesium (NMg) indicates that host rock aquifer has not undergone chloritisation. Accumulate contour plan of uranium ore body shows NW-SE trend and coincides with the hydro-uranium contour. Correlation sections of ore body display true as well as false hydro-uranium anomalies in N-S and E-W profiles. Hydro-uranium anomalies owe their origin to uranium cations, dissolved from the mineralized horizon in to groundwater. Hydro-geochemical orientation survey carried out at Chitrial plateau may be applied regionally in the Srisailam sub basin as an effective tool to explore the concealed unconformity type uranium mineralization below Srisailam Formation.Keywords
Hydrouranium Contours, Chitrial Plateau, Srisailam Formation, Accumulate Contour Map, Andhra Pradesh.References
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