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

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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K. K. Sinha ¹, Pradeep Pandey ¹, C. L. Bhairam ¹, P. S. Parihar ²

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, West Block VII, R.K. Puram, New Delhi - 110 067, IN
2 Atomic Minerals Directorate for Exploration and Research, AMD Complex, 1-10-153/156, Begumpet, Hyderabad - 500 016, IN

Abstract

In the western part of Bundelkhand massif, a caldera with intra-caldera sediments, known as Dhala Formation, occurs as an outlier in and around Mohar village of Shivpuri district, Madhya Pradesh. For the first time, occurrence of peperite is being reported from the basal part of the Dhala sediment. Two types of peperites have been recognized: blocky and fluidal or globular with variable morphology. In peperitic zones, features like soft sediment deformations, presence of sediment into the rhyolite along cracks, vesiculation of the sediments and other evidences suggestive of sediment fluidization are some definite characteristics of interaction of hot magma with wet sediments forming peperite. The occurrence of peperites reflects the contemporaniety of deposition of the Dhala sediments and volcanism, which is well in accordance to the volcanic origin of Dhala structure. Further, the nature of unconformity between the Dhala and overlying Kaimur which is characterized by merely a few centimeter thick pebbly/conglomeratic bed does not appear to represent a large hiatus as expected between the Semri and Kaimur of Vindhyan Supergroup. So, the contemporaniety of the Dhala Formation (at least the lower part) as reflected by occurrence of peperites, coupled with the available age of the rhyolite and the nature of the unconformity between the Dhala and overlying Kaimur provide convincing evidence to correlate the Dhala Formation with the Lower part of the Kaimur and unlikely with the Semri Group or Bijawar as proposed earlier.

Keywords

Caldera, Peperites, Dhala Sediment, Bundelkhand, Vindhyans, Madhya Pradesh.

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Kalyan Chakrabarti ¹, N. R. R. Ecka ¹, B. Mishra ¹, P. V. Ramesh Babu ², P. S. Parihar ²

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Jamshedpur - 831 002, IN
2 Atomic Minerals Directorate for Exploration and Research, Hyderabad - 500 016, IN

Abstract

Ground Radiometric survey of Paleoproterozoic pyritiferous quartz-pebble conglomerate (QPC) occurring to the north of Pallahara area led to the discovery of a QPC type uranium mineralisation near Mankarhachua village. Significant radioactivity is recorded in three sub-parallel uraniferous QPC horizons with metamorphosed pebbly to medium grained recrystallised massive sandstones. Detrital grains of uranothorite, thorite, radioactive allanite, monazite, zircon, minute uraninite grains in carbonaceous matter and thucolite contributes to the radioactive phases present in QPC matrix. Adsorbed U on limonite and goethite, secondary uranyl minerals in matrix, along bedding planes and fractures are commonly observed. This discovery has opened up a new horizon for future exploration for QPC type uranium mineralization in the area. The paper presents observations on geology, radioactivity, petrological and geochemical nature of the uraniferous QPC horizons.

Keywords

Conglomerate, Uranium Mineralization, Orissa.

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K. Mahendra Kumar ¹, Madhuparna Roy ², G. Behra ², P. S. Parihar ², R. K. Gupta ³, Jamger Singh ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research Shillong 793011, IN
2 Atomic Minerals Directorate for Exploration and Research New Delhi 10066, IN
3 Atomic Minerals Directorate for Exploration and Research Hyderabad 500016, IN

Abstract

Pegmatitic injections within the magnetite bearing granitoid host rare metal and rare earth mineralisation at Jaurahi, Sonbhadra district, Uttar Pradesh. The ore minerals identified are columbite, eschynite, samarskite, fergusonite, monazite, thorite, uranothorite and zircon in association with magnetite, ilmenite and rutile. Samples of mineralised pegmatite have analysed 0.65 to 4.42% Nb and 0.55 to 4.85% Y.

Keywords

Economic Geology, Pegmatite, Columbite, Granitoid, Chhotanagpur Gneissic Complex, Sonbhadra, Uttar Pradesh.

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A. Markandeyulu ¹, I. Patra ¹, B. V. S. N. Raju ¹, A. K. Chaturvedi ¹, P. S. Parihar ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, AMD Complex, Begumpet, Hyderabad – 500 629, IN

Abstract

The Paleo-Meso Proterozoic Gwalior basin (E - W), lying to NW fringe of Bundelkhand massif is represented by litho-package of lower arenaceous Par Formation and upper chemogenic Morar Formation. It is bounded by Indo- Gangetic alluvium in north and east, Kaimur sediments in west and Bundelkhand granitoids in south. Gwalior Basin has been the exploration target for uranium mineralization right from early 60's. Surface radioactivity anomalies due to uranium has been reported in both Par and Morar Formations of Gwalior Group and Vindhyan sediments. Besides presence of syngenetic uranium in the system, presence of post-depositional faults and fractures are the favorable factors. Aeromagnetic survey was carried out by AMD in 2002 with N-S lines of 500 m interval covering 9406 line km. The data with sampling interval of 0.1 sec was corrected for spikes, diurnal variation, IGRF, heading and lag. Final processed images are prepared after suitable leveling and gridding. First vertical derivative of TMI-RTP and tilt-angle derivative images are used to map the litho-contacts, lineaments and structural features. Numerous NE-SW trending low amplitude and NW-SE trending high amplitude magnetic linears corroborate with quartz reefs and basic dykes respectively. Besides, E-W to WNW-ESE and ENE-WSW trending fractures are also evident from the processed image maps. Further, the Euler's depth solution of gridded aeromagnetic data calculated for structural indices of 0 and 1 are very consistent in locating the position of the causative sources. Based on the amplitude and textural character of processed aeromagnetic data, alteration zone is delineated well within the Morar Formation. Enhanced Thematic Mapper (ETM+) image with 30m resolution was merged with IRS PAN 1D (5.8 m resolution) for better spatial/radiometric resolution to extract lithocontacts and lineament patterns. Merged PAN band-4 after linear contrast and edge enhancement techniques deciphered detailed lineament pattern, which corroborate the magnetic data. Merged ETM+ (RGB 751) and PC (PC1-PC2-PC5) images depict litho-logical contrast. Integration of aeromagnetic and satellite imagery data helped in understanding the structural fabric of the Gwalior Basin and to identify favorable loci of uranium mineralization.

Keywords

Gwalior Basin, Aeromagnetic Survey, Satellite Imagery, Structural Fabric.

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