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

K. B. Anantharaman ¹, S. Sethuram ¹

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, Hyderabad, IN

Abstract

Abnormally radioactive granitoids are targets of uranium exploration because they can be the source for uranium deposits as well as the hosts. Significant uranium mineralization is known to occur northwest of Suryamalai granite batholith at Kullampatti situated 40 km southwest of Salem. This paper embodies the geophysical exploration for uranium, using results of magnetic and radiometric methods. The investigations revealed that uranium mineralization is structurally controlled and such structures have magnetic expression. Incidentally, correlation of anomalous content of W with U is also brought to light.

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R. L. N. Rao ¹, R. Srinivas ¹, S. Sethuram ¹, J. R. Subba Rao ¹

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, Begumpet, Hyderabad - 500 016, IN

Abstract

Interpretation of gravity and magnetic data in a strip of 250 sq.km. over Lanji-Darekasa tract of Khairagarh basin has been attempted in order to delineate regional structures and controls of uranium mineralisation in the province. Magnetic map indicates three parallel east-west trending lineaments representing basic dykes cutting across the geologic fonnations. The orthogonally intersecting gravity and magnetic trends around Saheki (80° 31' : 21° 27' 30") reveal a tectonised zone favourable for uranium minelisation. Gravity low of the order of five milligals near Nimbanaka (21° 19' : 80° 31' ) suggests a sharp increase in the thickness of Bijli rhyolites.

Based on observed gravity, magnetic data and the available surface geological information, the paper proposes a model for configuration of Khairagarh basin along Lat. 21° 25' between Parsori and Khairagarh. Maximum thickness for volcano-sedimentary pile filling the basin along this section is estimated to be around 2300m. The model also indicates possibility for the presence of a concealed high density formation (Pitepani Volcanics?) below Bortalao sandstones.

Keywords

Geophysics, Khairagarh Basin, Madhya Pradesh.

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R. L. N. Rao ¹, S. Sethuram ¹, Subhash Ram ², B. N. Rao ¹, K. L. Tiku ¹

Affiliations
1 Department of Atomic Energy, Hyderabad - 500 016, IN
2 Department of Atomic Energy, Nagpur - 440 001, IN

Abstract

Geophysical methods have been extensively used for delineation of structural features such as fractures and shear zones which often control and host economic mineralisation. Numerous fractures hosting uranium mineralisation and confined to younger intrusives and leucogranites occur within basement gneissic complex on the southwestern margin of the Mesoproterozoic Cuddapah basin. The geophysical signatures of one such mineralised fractore zone near Mulapalle are discussed. Mineralised fractures are mostly confined to a zone of cataclastic rocks characterised by widely varying magnetic character with respect to the surroundings. A strong redox barrier associated with the mineralisation is revealed by seIf-potential data. The mineralised zone is also indicated by a higher order resistivity attributable to the enrichment of silica in the fracture zone.

Keywords

Geophysics, Fracture, Redox Barrier, Uranium Mineralisation, Peninsular Gneiss, Cuddapah Basin, Andhra Pradesh.

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