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

G. R. Gangadharan ¹, K. K. Achar ¹, K. Umamaheswar ¹, Mary K. Kumar ¹

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

Abstract

No Abstract.

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D. B. Sen ¹, Suresh Kumar ¹, G. R. Gangadharan ¹

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, West Block VII, R.K. Puram, New Delhi-110 066, IN

Abstract

Several shear-controlled and fracture-filled/disseminated type uranium occurrences are known in the Rampur Window. This paper presents the geology and genetic aspects of fracture-filled type of mineralisation in Chhinjra area on the basis of recent stratigraphical, geochronological and tectonic data. Based on the angular unconformity between Manikaran quartzites and overlying chlorite phyllites, the geological evolution of Chhinjra area has been reconstructed in two stages: Pre-unconformity and post-unconformity. Each stage is characterised by different phases of deformation with typical structural style and accompanying mineralisation processes. Four major tectonic events can be recognised here, namely 2500 Ma, 1200 Ma, 700 Ma and 55 Ma. Each event has left its imprint on the rocks as well as uranium mineralisation of Chhinjra area.

Keywords

Uranium Mineralisation, Structural Geology, Chhinjra Area, Rampur Window, Himachal 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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