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

S. Srinivas ¹, A. S. K. Murthy ², G. S. Yadav ², K. M. Srivastava ²

Affiliations
1 Plot No 12, Vtkaspuu, S R Nagat (Post), Hyderabad 500 038, IN
2 Department of Geophysics, Banaias Hindu University Varanasi 221005, IN

Abstract

The Chattisgarh Basin ot the Ccntial Indian Piecambnan Shield is one of the Puiana basins of Meso to Neopioteiozoic age which has not been geophysically investigated in good detail so far Under the Deep Continental Studies Pioject, two regional magnetic piofiies over a stietch of 382 and 403 km acioss the Chattisgaih legion weie can led out fot the fust time in ncai east west and noith south dnections respectively

The Chattisgaih Basin lecoided a bioad magnetic high compared to Sakoh Belt and Dongargaih Supergioup in the west and Sonakhan Greenstone Belt in the east which were reflected as lows on either side of the basin Two dimensional modelling of the data reveals a maximum thickness ot 3000 m toi the Chattisgaih sediments The acidic and basic volcanic locks associated with Sakohs Dongargarh, Sonakhan Greenstone belt and Kondagaon Granuhte belt weie demaicated and their geometiy decipheied The Indravati sediments along north south piofile indicate a maximum thickness of 2500 m Besides this, modelling of magnetic data also leveals the presence of possible inti usives into the Chattisgaih and Indravati sediments / basement

Based on the model lesults and available geological information an attempt is made to study the natuie of the uppei ciust beneath die Chattisgarh basin It appeals that the detritus to the basin sediments is derived fiom the basic locks in the centie, aiound Raipur while the peripheries are of gtanitic / acidic natuie indicating a ring type stiuctuie.

Keywords

Geophysics Magnetic Modelling, Ciustal Structuie, Pioterozoic Chattisgarh Region.

Full Text

     

G. S. Yadav ¹, Rakesh Mohan ², H. K. Sabot ³, M. Nagendra Kumar ², S. Q. Hoda ²

Affiliations
1 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Jaipur - 302 030, IN
2 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Shillong - 793 011, IN
3 Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Hyderabad - 500 016, IN

Abstract

Significant Sandstone-Type uranium mineralisation is recorded from the Rongcheng Plateau and Rongdi nala, located north and WNW of Balphakram Plateau, South Garo Hills district, Meghalaya. Mineralisation is associated with grey coloured, medium to coarse grained, poorly sorted arkosic Wacke-Subarkose suite of sandstones, belonging to the late Cretaceous Mahadek Formation. Sixteen uranium occurrences located 2-30 m above crystalline basement and with dimensions varying from 5 to 300 m × 0.5 to 4 m, have been identified. Grab samples have assayed up to 0.52% eU₃O₈ 0.46%U₃O₈ (beta/gamma) and <0.010%Tho₃. The fertile Precambrian basement crystallines constitute the source of uranium. Presence of organic matter and pyrite in the sandstone provided reducing environment for deposition of pitchblende as the principal discrete uranium mineral.

Keywords

U-mineralisaton, Sandstone-Type, Mahadek Formation, Uraninite, Balphakram Area, Meghalaya.

Full Text