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

Sunil Kumar ¹, S. K. Dash ¹, U. P. Sharma ¹, K. Ramadoss ¹, Rajendra Singh ², K. K. Dwivedy ²

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, Bangalore-560072, IN
2 Atomic Minerals Division, Department of Atomic Energy, Hyderabad-500016, IN

Abstract

Univariate and multivariate statistical analyses, especially correlation study and factor analysis of uranium and other major ions in the groundwater of Chenchalapalle-Mulapalle area, known for its fracture controlled uranium mineralization, in the southwestern crystalline margin of Middle-Upper Proterozoic Cuddapah basin have revealed - (i) several well defined and distinct anomaly zones of > 200, > 500, > 1000 ppb of uranium, (ii) enriching factors like TDS(Ec), HCO₃^-, Na⁺, K⁺, Ca⁺² , Mg⁺², Cl^-, SO₄^-2 have poor to negligible influence on high uranium content and (iii) factor-3, identified as "mineralization factor" has high loading for uranium (0.948). The study on saturation indices of several uranium and other minerals indicated undersaturation for most of the aqueous uranium species, except for a few hydroxides. Particularly, schoepite (2UO₃.5H₂O) has low to moderate degree of supersaturation in samples from major anomalous zones.

Based on the distinctive hydrogeochemical attributes and geological and structural favourability factors, the tracts in the vicinity of Varikuntapalle (VKP). Dapepalle (DPL) and Pulikunta (PLK) villages, between Chenchalapalle-Mulapalle area in the southwestern crystalline margin of Cuddapah basin, are designated as potential target areas for detailed exploration.

Keywords

Hydrogeochemistry, Uranium, Groundwater, Cuddapah Basin, Andhra Pradesh.

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Himadri Basu ¹, G. R. Gangadharan ¹, Suresh Kuman ¹, U. P. Sharma ¹, A. K. Rai ¹, Anjan Chaki ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Nagarbhavi, Bangalore 560 072, IN

Abstract

Middle Proterozoic Gulcheru Quartzite marks the onset of sedimentation, after the Eparchaean unconforrnity, in the Cuddapah Basin. In the southwestern margin of the basin it is made up dominantly of orthoquartzites. On the basis of lithology, stratigraphic relationship, bedding characteristics, texture and colour of sediments and sedimentary structures, five lithofacies were recognized within Gulcheru Quartzite. The Gulcheru Quartzite, though dominantly of shallow marine origin, shows imprints of other depositional regimes. Detailed interpretation of the facies and study of their field relationships reveal that pink massive quartzite, the lowermost unit of Gulcheru Quartzite, is of fluvio-aeolian origin. Later marine transgression .led to the development of a moderate to low energy beach, which evolved with time into a barrier: spit complex.

Keywords

Depositional environment, Facies analysis, Fluvio-Aeolian, Barrier-Spit, Gulcheru Quartzite, Cuddapah Basin, Andhra Pradesh.

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S. Zakaulla ¹, K. Umamaheswar ², P. V. Tirupathi ¹, U. P. Sharma ¹, H. Basu ¹, M. A. Ali ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Nagarabhavi, Bangalore, IN
2 Atomic Minerals Directorate for Exploration and Research, Nagarabhavi, Shillong, IN

Abstract

Gulcheru Formation constitutes 200 m-250 m thick siliciclastic sediments Based on grain size texture and colour of the sediments, four distinct facies are demarcated They are pink massive quartzite, cross bedded grey quartzite, purple siltstone and pitted quartzite The ratios of Si/Al is higher (62 9 to 292 18) in pitted quartzite and lowest (2 122 - 18 247) in siltstone, where as grey quartzite has wide range of 3 78 - 8637 67 Ths difference is essentially due to higher quartz content in pitted quartzite and dominance of clays/shaly component in siltstone The wide range of Si/Al ratio in grey quartzlie is due to interlayering of siltstone/shale laminations/bands Distribution of uranium indicates grey quartzite (av U₃0₈= 9 9 ppm) and siltstone (av 15 42 ppm) have higher intrinsic uranium than that of pitted quartzite (average 5 6 ppm) and pink massive quartzite (average 7ppm) which is considered very high in comparison to normal sandstone (av = 0 5ppm, Taylor, 1965) Trace elements like Mo, V, Ni, Cu and Pb are enriched in mineralised grey quartzite Pitchblende is the man uranium mineral in grey and pitted quartzite unlts It occurs as fracture fillings and also as interstital material, associated intimately with chlorite Close association between pitchblende and sulphides like pyrite, chalcopyrite and galena is seen when pitchblende occurs as fracture fills Uranium in siltstone, is generally in adsorbed form with ferruginous material, where as associated trace elements like Mo (r = 0 515), V (r = 0 806), Nt (r = 0 4) and even Ti0₂, (r = 0 87) are well correlated with Al₂0₃, suggesting their clays/phyllosilicates U/Pb dating of uraniferous grey quartzite indicated ages of 1336k±4 Ma and 446±29 Ma suggesting remobilisation and concentration of intrinsic uranium.

Keywords

Gulcheru Formation, Cuddapah Supergroup, Siliciclastic Sediments, Uranium incidence, Gandi Area, Andhra Pradesh.

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