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

Anand Kumar Srivastava ¹, Gopendra Kumar ², D. Bhattacharya ³

Affiliations
1 Department of Geology, Lucknow University, Lucknow, IN
2 48 Pandariba, Lucknow - 226 004, IN
3 AMD/DAE, NR, West Block - 7, R K Puram, New Delhi - 110 066, IN

Abstract

No Abstract.

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D. Bhattacharya ¹, Madhuparna Roy ¹, Dhirendra Kumar ², Pawan Misra ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, NR, New Delhi - 110 066, IN
2 Flat No. B-170, Kendnya Vihar, Sector-51, Noida, IN

Abstract

The Lower Proterozotc (1800-2400 Ma) Jungel Valley mafic-ultramatic complex (JVMUC) is an integral pait of Mahakoshal greenstone belt in district Sonbhadra. The complex is known for its diversity of locks like alkali olivine basalt, kimbeihte and ultramalic lamprophyre. In addition to these, a carbonate rich rock having igneous affinity is being reported for the first time from this complex High CaO, CO₂, Sr and Ce with low SiO,, A1₂O₈ and TiO₂ characterise this rock. However, these rocks are not significantly enriched in incompatible elements and REE, implying that these may have possibly formed by partial melting of a depleted mantle at shallow depth. The geochemical characters combined with association of mantle derived rocks, presence of high level of carbonate in the lamprophyre and absence of sedimentary limestone in the area point towards an igneous origin, probably as a residual concentrate of a differentiated Kimberlite-Ultramahc lamprophyre sequence Sr isotope data, which fall well within the range of reported carbonatites of India, suggest moderate crustal contamination. The mafic-ultramafic suite together with the carbonate rocks developed in Son-Naimada nit zone are interpreted to be coeval with the intrusive syenite pluton, alkali gabbio and lamprophyres of the adjoining areas and is related to the development of Mahakoshal greenstone belt.

Keywords

Jungel Valley, Caibonate Lamprophyre, Mahakoshal Greenstone Belt, Uttar Pradesh.

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D. Bhattacharya ¹, Madhuparna Roy ¹, G. B. Joshi ¹

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, New Delhi-11 0066, IN

Abstract

Field observations, petromineralogical and geochemical studies on the locks of Jhirgadanpdi pluton indicate three phases of igneous activity, compositionally ranging from gianodiorite, Quartz-Monzonite to granite. The wide spread intermediate phase of this suite shows anomalous concentration of U, Ce and Th as compared to average granite and enrichment of K, Rb, Ba relative to Zr, Nb and Y. The radioactive minerals identified are thorite, uranothorite, allanite monazite and samaiskite Molybdenite and chalcopyite are the other are minerals Presence of REE (1 are earth element) minerals, distibution pattern of LIL (large Ion lithophile) elements, various elemental ratios and increasing metaluminous tendency indicate moderate degree of differentiation Petromineralogical study of rocks suggests partial melting of a magic source of lower crustal rocks Geochemical data suggests that the granitic rocks of the three phases are comagmatic. Available age data together with tectonic considerations indicate that the magmatic activity is relaled to the development of Mahakoshal greenstone belt which might have culminated with the emplacement of Post-Tectonic Jhirgadandi sulte (∼ 1800 Ma), possibly under the influence of a mantle plume.

Keywords

Jhirgadandi Granite Post-Tectonic, Mantle Plume Radloactive Minerals Sonbhadra District, Uttar Pradesh

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A. Chaki ¹, D. Bhattacharya ², J. S. Rao ³, A. K. Chaturvedi ³, A. K. Bagchi ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy Bangalore - 560 072, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy NewDelhi - 110 066, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy Hyderabad 500 016, IN

Abstract

Rb-Sr isotopic data for the Tamparkola granite, northwest of Bonaigarh, and Bamra granite, southeast of Barnra, Sundergarh district, Orissa have yielded similar ages of 2746&#177144 Ma and 2738±28 Ma, respectively. Small granite exposures intruding the Iron Ore Group in the southern part of Tamparkola granite, have also indicated similar Whole Rock Rb-Sr age of 2867&#17786 Ma. These may be correlated with the Bonai granite. Significant crustal component was involved in the generation of these granites, as indicated by high initial Sr ratio, and their emplacement probably marks a major terminal cratonisation event in northwestern part of the Singhbhum-North Orissa Craton.

Ths study does not support the view that the Tamparkola Granite is equivalent to the Itrna/Ekma granites that are intrusive into the Gangpur Group. These age results call for a revision of the stratigraphy of the Bonai-Gangpur tract, in that the Darjing Group unconformably overlies both the Bonai granite and Tamparkola granite, with the Mesoproterozoic Kunjar sedimentary sequence representing the youngest of the regional succession.

Keywords

Rb-Sr isotopics, granites, stratigraphy, Kunjar basin, Darjing Group, Gangpur Group, Sundergarh District, Orissa.

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Aniruddha Basu ¹, L. K. Das ¹, M. Moitra ¹, D. Bhattacharya ¹, A. K. Lahiri ¹

Affiliations
1 Marine Wing (HQ). GSI, Kolkata, Bhubijnan Bhawan, Karunamoyee, Salt Lake, Kolkata - 700 091, IN

Abstract

This note records the occurrence of a lamproitic body traversing the Archaean greenstone belt in Singhbhum craton near Rajnagar-Tiring area in east Singhbhum district of Jharkhand. This discovery opens up new vistas of search for similar rocks in this region.

Keywords

Lamproites, Singhbhum Granite, Rajnagar Tiring Area, Jharkhand.

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S. Viswanathan ¹, D. Bhattacharya ²

Affiliations
1 Flat B-203, Block-B, Unite Avenue Apts, South End, 7-1-29, Ameerpet, Hyderabad - 500 016, IN
2 AMD/DAE, NR West Block-7, R K Puram, New Delhi - 66, IN

Abstract

No Abstract.

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D. Bhattacharya ¹, G. B. Joshi ¹, G. S. Sharma ², D. B. Sen ³

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, New Delhi-110066, IN
2 Atomic Minerals Directorate for Exploration and Research, Jaipur -302030, IN
3 Atomic Minerals Directorate for Exploration and Research, 313/4, Sector-56, Rail Vihar, Gurgaon, Haryana, IN

Abstract

Surface indications of uranium mineralisation associated with ferruginised brecciated rocks is traceable, intermittently, over a strike length of 25 km, exposed along the Jamual -Markundi Fault (JMF), at the tectonic contact of Neo- to Meso-Proterozoic Vindhyan Supergroup and Paleo-Proterozoic Mahakoshal Group between Gurdah and Mohariya, Sonbhadra and Sidhi districts of U.P. and M.P. respectively. Preliminary investigations reveal uranium (U₃O_g) content upto 610 ppm with little or no ThO₂. Uranium occurs in adsorbed state in the ferruginised groundmass of brecciated rock and probably related to hydrothermal activity. This is the first reported uranium occurrence from this unconformity related geological set up in the Son valley.

Keywords

Uranium mineralisation, Unconformity, Jamual-Markundi fault, Son-valley, U.P., M.P.

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