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

Syed H. Akhter ¹, A. K. Bhattacharya ¹, D. K. Sen Gupta ¹, I. K. Kaul ¹

Affiliations
1 Department of Geology and Geophysics, I. I. T., Kharagpur 721 302, IN

Abstract

Thermoluminescence (TL) studies on the metasediments of Jabar, lying in the northwestern part of Purulia district of West Bengal, show natural thermoluminescence (NTL). These metasediments of Precambrian age, predominantly consist of marble, calc-silicates and granite gneiss. Each of the representative rock sample exhibits distinct TL glow-curves which can be successfully utilised in a number of geological applications. On the basis of natural as well as artificial thermoluminescence glow-curves, two distinct types of marble sequence have been identified.

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S. K. Som ¹, A. K. Bhattacharya ¹

Affiliations
1 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur 721302, IN

Abstract

Recent weathering of Panchpatmali bauxite-bearing terrain, Koraput district, Orissa has been discussed in terms of groundwater geochemistry. pH and Eh are in favour of Fe (OHh development, whereas Na⁺ : Ca²⁺ vs. HCO₃ : SiO₂, HCO₃ : SiO₂ vs. ppm HCO) and pH -pNa, 2pH -pCa, pK-pH vs. -log [H₄ Si0₄] are all in favour of kaolinite development with a minor amount of gibbsite. These observations have been confirmed by X.R.D., I.R., and S.E.M. of the recent weathered samples of the area. The condition of development of these mineral phases with respect to C0₂ has  also been discussed.

Keywords

Ground Water Geochemistry, Weathering, Bauxite, Koraput, Orissa.

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S. K. Som ¹, A. K. Bhattacharya ²

Affiliations
1 Geological Survey of India, Unit: VIII : Nayapalli, Bhubaneswar - 751 012, IN
2 Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur - 721 302, IN

Abstract

Mineralogy of bauxite profile, after khondalite parentage, at Panchpatmdi area, Koraput district, Orissa is studied by XRD, JR, DTA and Optical/electron microscopy. XRD shows thedominance of kaolinite in saprolite, whereas IR and DTA results confirm its presence in the entire profile. All the above studies confirm the strongly disordered nature of kaolinite. Gibbsite, geothite, hematite, diaspore and allophane are present in the entire profile with the intermittent occurrence of boehrnite, anatase, and futile. Microscopic investigation reveals poIycyclic crystalisation of gibbsite and ultimately resilicated to kaolinitevia dlophane. Transformation of alurninious parent minerals to gibbsite is direct without the intermediate kaolinite stage. Evidences are presented to show that gibbsites are later transformed to kaolinite due to ground water activities.

Keywords

Bauxite, Mineralogy, Panchpatmali, Orissa.

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A. Basu ¹, A. K. Bhattacharya ¹, D. K. Paul ²

Affiliations
1 Geological Survey of India, 15 A & B Kyd Street, Calcutta - 700 016, IN
2 Indian School of Mines, Dhanbad - 826 004, IN

Abstract

The dyke swarms intruding the Gondwana sequence in the east Bokara Coalfield, Bihar include lamprophyres and lamproites such as olivine lamproties, olivine-leucite lamproites and leucite lamproites. Basic intrusives and rare siderite rich carbonates (carbonatite ?) are also found. The olivine lamproites contain xenocrysts of olivine and rare xenoliths of harzburgite. Gold values upto 3.6 ppm on grab samples have been noted from the intrusive rocks in the area. These lampropbyric rocks are considered to have formed from a highly incompatible element enriched metasomatised mantle source probably of harzburgitic composition.

Keywords

Petrology, Geochemistry, Lamprophyric Rocks, Gold, Bokaro Coalfield, Bihar.

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T. K. Mallik ¹, A. K. Bhattacharya ²

Affiliations
1 FD-317, Sector - III, Salt Lake, Kolkata -700 106, IN
2 Geological Survey of India, Eastern Region, Salt Lake, Kolkata - 700 091, IN

Abstract

Samples from the Kaolinite deposits at Bagru Hills, Lohardaga, Bihar have heavy mineral assemblage of rutile, opaque, tourmaline, biotite, staurolite, pyroxene, sphene, epidote, zircon, kyanite, muscovite and tremolite/actinolite derived from igneous and metamorphic sources. The lighter fraction includes iron hydroxides, chlorite, feldspar, carbonate and some muscovite or limonite. The major, minor and trace elements remain nearly the same irrespective of colouration of samples. The chemical composition and the size of the kaolinite grains coupled with its purity clearly indicate that it can be used in a number of industries.

Keywords

Kaolinite, Bauxite, Heavy Minerals, Differential Thermal Analysis, X-Ray Differentiation, Chemical Analysis, Bagru Hills, Lohardaga, Bihar.

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A. K. Bhattacharya ¹, N. Dhar ¹, S. Lahiri ¹

Affiliations
1 Opn: WB-SK-A&N, Geological Survey of India, North Block, 41h Floor, DK-6, Sector II, Salt Lake, Kolkata - 700 091, IN

Abstract

No Abstract.

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