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

A. K. Roy ¹, A. Saha ², R. P. Singh ³, R. M. Sinha ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, New Delhi, IN
2 Atomic Minerals Directorate for Exploration and Research Jamshedpur, IN
3 Atomic Minerals Directorate for Exploration and Research, Hyderabad-16, IN

Abstract

A radioactive fault breccia zone trending N30°E is exposed intermittently within the puru granite dome, near Kuchanapalle village in the NE margin of Cuddapah basin. A major part of the fault zone is under soil cover. Within this fault zone, a dark coloured ferruginous and uraniferous fault breccia is exposed over an area of 150m x 2.5m. In order to trace the continuity of the concealed fault zone, the uraniferous breccia zone was tested by closed circuit soil-gas radon (CCT) measurement, solid state nuclear track detection (SSNTD) survey, and trace element analysis of augur-hole soil samples. Radon levels in 164 auger holes vary from 9 to 863 per 50 sec. The alpha track density on cellulose nitrate films used in SSNTD surveys varies from 27 to 820 per sq. mm. The iso-alpha track density map has confirmed the anomalous patterns obtained by the soil-radon survey.

Trace element data of soil samples have been processed using R-mode factor analysis of correlation matrix. These data along with radon and SSNTD surveys have thus been found to be very effective in delineating the extension of the radioactive breccia zone under soil cover, up to 1200 m towards north.

Keywords

Economic Geology, Exploration Geochemistry, Soil Radon Surveys, Uranium, Cuddapah Basin, Andhra Pradesh.

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Minati Roy ¹, A. K. Roy ², P. S. Parihar ³

Affiliations
1 AMD, Department of Atomic Energy, Northern Region, New Delhi-110066, IN
2 AMD, Department of Atomic Energy, F-1149, Chittaranjan Park, New Delhi (Ex AMD, NR, New Delhi), IN
3 AMD, Department of Atomic Energy, Head Quarter, Hyderabad-500016, IN

Abstract

Radioactive carbonaceous matter, possibly of organic origin, with coffinite inclusions {U(SiO₄)_{1_x}(OH)_4x} are reported for the first time in the fractures within the core samples of highly deformed Bundelkhand granitoids in the Gwalior Basin. Intense hydrothermal alterations along these fractures are manifested in the form of silicification, argillic alteration (clay formation), chlontisation, ferruginisation and by sulphide formation. The globular radioactive carbonaceous matter is of organic origin and generally associated with silica rich veins. Globular nature of this carbonaceous matter indicates their formation from coagulation of smaller colloids in a low temperature hydrotherm. Mixing of descending oxidizing hydrotherm derived from basinal fluid rich in heavy metals, uranium, organic matter and ascending reducing fluid (hydrotherm) rich in H₂S and Si in these fracture zones has resulted in the precipitation of sulphides, secondary quartz, carbonaceous material and coffinite.

Keywords

Radioactive Material, Bundelkhand Granite, Gwalior Basin, Madhya Pradesh.

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