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B. K. Nayak ¹, V. Panchapakesan ²

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun 248001 (U.P.), IN
2 Department of Earth Sciences, I.I.T., Bombay 400076, IN

Abstract

The thermodynamical calculations for the oxygen and sulphur fugacities of Mosaboni mineralisation have been made based on the equilibrium reactions for various mineralogical associations like, (a) bornite-pyrite-chalcopyrite. (b) pyrite-pyrrhotite. (c) pyrite-magnetite, (d) pyrrhotite-magnetite and (e) pyrite-pyrrhotite-magnetite and the temperatures determined by fluid inclusion studies. The association of pyrite-pyrrhotite-magnetite indicates that oxygen fugacity was 10^-24.3 atmosphere at 450°C and this got reduced to 10^-32.5 atmosphere at 300°C. Presence of bornite in place of magnetite shows that there was fluctuation in the fugacity of sulphur. This might be varying from 10^-6.3 to ^-1.6 atmosphere at 450°C and from 10^-11.6 to 10^-6.4 atmosphere at 300°C.

Keywords

Fluid Inclusion, Thermodynamics. Mosaboni, Sulphide Mineralization, Bihar.

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B. K. Nayak ¹, V. Panchapakesan ²

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun 248 001 (U.P.), IN
2 Department of Earth Sciences, LLT., Bombay 400 076, IN

Abstract

There exists a strong control of fluid inclusion homogenization temperature on the assay of copper ore in the Mosaboni mine. The ores, having copper assay greater than or equal to 1.5%,are more or less confined to a homogenization temperature range of 320° and 360°C. This also reflects that these ores were precipitated within narrow salinity limits of 38.6 and 42.8 equivalent wt. per cent NaCl. The homogenization temperature varied between 275° and 420°C with the highest recorded temperatures at the bottom levels indicating that the ore-forming fluids came from below and migrated upward precipitating various grades of ores at favourable sites under suitable physico-chemical conditions.

Keywords

Fluid Inclusion, Economic Geology, Mosaboni Mine, Singhbhum, Bihar.

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B. K. Nayak ¹, Rajesh Sharma ²

Affiliations
1 Regional Research Laboratory, Bhubaneswar 751013, IN
2 Wadia Institute of Himalayan Geology, Dehra Dun 248001, IN

Abstract

A strong stratigraphic control is exhibited by the sporadic Pb-Zn occurrences in the Great Limestone of Riasi, J & K. Fluid inclusion thermometry and stable isotope data suggest their remobilisation and concentration in the fractures developed in the host-rock at the time of orogenic movements and the final deposition may be due to the mingling of at least two fluids; one epithermal; generated due to orogenesis and the other, meteoric water.

Keywords

Pb-Zn Mineralization, Great Limestone, Riasi, Jammu and Kashmir, Fluid Inclusion.

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B. K. Nayak ¹, V. Panchapakesan ²

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun - 248 001 (U.P.), IN
2 Department of Earth Sciences, I.I.T. Powai, Bombay - 400076, IN

Abstract

The equation, N = 2πX²/√3, has been derived to find out the number of hexagonally distributed points (N), in a given circle of radius 'R' and the point-point distance 'd'. where X = R/d. For a given set of microscopic conditions, the above equation is applied to construct 4 standard circular graphic charts. An, attempt has been made to use these charts to study the population of fluid inclusions, by visual comparison, in the quartz samples intimately associated with the sulphides collected from the Mosaboni mine of Bihar.

Keywords

Fluid Inclusion, Mosaboni, Bihar.

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S. K. Das ¹, R. K. Sahoo ¹, J. Muralidhar ¹, B. K. Nayak ¹

Affiliations
1 Regional Research Laboratory, Bhubaneswar-751013, Orissa, IN

Abstract

In the Sukinda ultramafic belt of Orissa, significant deposits of nickeliferous laterite have formed by weathering of large chromiferous dunite-peridotite suite of rocks. Two typical laterite profiles obtained by drilling (BH-1 = 50 m and BH-2 = 46 m) from Kansa sector of Sukinda belt were studied in order to establish petrochemical relationships between supergene Ni-laterites and the parent rock. In BH-1, ferruginous layers comprise the profile where goethite is intimately admixed with quartz, kaolinite and gibbsite at various depths. In BH-2, a complete laterite profile from bed rock (altered dunite) to top pisolitic laterite with transitional clay-serpentinite zone is encountered. The altered dunite is essentially composed of olivine (FO_93.8 ≅ 35% vol.) and serpentine. The clay-serpentinite zone consists of varying proportions of smectite clay (nontronite) and antigorite with minor amount of chromite, goethite and quartz. This zone is enriched in Ni with a maximum value of 1.09% Ni. In the ochreous ferruginous zone overlying clay-serpentinite zone, serpentine and nontronite disappear completely and goethite constitutes the principal mineral with varying proportions of secondary quartz. This zone is rich in Fe, Ni, Co, Mn, Al and Cr and is formed by residual concentration of stable oxides. Mass-balance equation assuming Cr₂O₃ as constant chemical constituent reveals that nickel is strongly accumulated in the clay-serpentinite zone. A second maximum in nickel concentration is found in ochreous ferruginous zone with almost complete removal of magnesium. Normalised major and trace element data generated on the bore hole samples have been processed, by using R-mode factor analysis of correlation matrix to understand the natural process of weathering. Leaching studies of the samples suggest that nickel occurs in adsorbed state within amorphous hydrated iron oxide and in weakly bonded and lattice bound states within gaethite and secondary silicates.

Keywords

Economic Geology, Geochemistry, Nickeliferous Laterite, Leaching, Sukinda, Orissa.

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B. K. Nayak ¹, S. K. Paul ¹

Affiliations
1 Wadia Institute of Himalayan Geology, Dehra Dun 248001, IN

Abstract

Antimony mineralisation occurs in the form of Sb-Pb-Zn and Sb sulphide veins in the fractures of the granites present close to the Tethyan Thrust near Barashigri glacier of Himachal Pradesh. SimiJar strike and dip patterns of the Tethyan Thrust and the mineralised fractures indicate that the mineralisation may be either syn- or post-thrusting event. Two types of primary inclusions observed in the quartz intimately associated with the sulphides are, (i) liquid + vapour (15-40% by volume) and (ii) liquid + vapour + dark crystal, the latter being found only in Sb-Pb-Zn veins. Heating and freezing studies of the inclusions reveal that the mineralising fluid was epithermal in nature having low salinity and the final deposition of the sulphides was through a simple cooling phenomenon.

Keywords

Fluid Inclusion, Antimony, Barashigri Glacier, Vein, Epithermal, Labaul and Spiti, Himachal Pradesh.

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B. K. Nayak ¹, V. Panchapakesan ²

Affiliations
1 Regional Research Laboratory, Bhubaneshwar, Orissa 751013, IN
2 Dept. of Earth Science, IIT, Bombay-400076, IN

Abstract

Distribution pattern of fluid inclusion homogenisation temparatures and assay of copper ores hove been uscd to ascertain the mineralising fluid ascent direction. Thetrigonametric relationships to calculate the parameters of this direction have been derived which show that the bearing of ascent of ore fluids isN 53.°E-S 53°W having plunge 38° and rake 77°. There is high probability of encountering rich ores underneath 30th level in a direction opposite to fluid ascent at selected locations.

Keywords

Fluid inclusions, Ecodornic Geology, Sulphide Deposits, Mosnboni, Bihar.

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B. K. Nayak ¹, B. C. Acharya ¹, R. K. Sahoo ¹

Affiliations
1 MM Division, Regional Research Lab., Bhubaneswar-751 013, IN

Abstract

Complex system of geochemical variables obtained from manganese ores of Balaghat mine, M.P., is simplified by using R-mode factor analysis of correlation matrix. Eighteen major oxides and trace elemental variable have been expressed in terms of the three common (rotated) factors and genetic interpretations of these factors have been brought out in relation to the manganese deposit.

Keywords

Factor Analysis, Manganese Ore, Balaghat, Madhya Pradesh.

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B. K. Nayak ¹, Swati Mohanty ¹, Rajeev ¹, R. K. Sahoo ¹

Affiliations
1 Regional Research Laboratory, Bhubaneswar-751013, IN

Abstract

Normalised major and trace element data of manganese ores from Nishikhal are processed by using R-mode factor analysis of correlation matrix. Twenty major and trace elemental variables are expressed in terms of 3 common (rotated) factors to understand the mineralogical occurrences and the processes of formation of the manganese deposit. Varimax factor scores are used to classify in a finer detail the manganese ore types.

Keywords

Factor Analysis, Geochemistry, Manganese Ore, Orissa.

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S. K. Das ¹, B. K. Nayak ¹, P. Chattopadhyay ¹, J. Muralidhar ¹, B. B. Nayak ¹, A. K. Singh ², R. K. Sahoo ³

Affiliations
1 Regional Research Laboratory, Bhubaneswar - 751 013, IN
2 2N3/278, IRC Village, Bhubaneswar - 751 015, IN
3 137, Jagganath Vihar, Bhubaneswar - 751 003, IN

Abstract

At Gopur, Onssa, auriferous quartz veins with stringers and rich disseminations of sulphides occur in the latcntes derived by tropical weathering of metabasaltic rocks. Minute to coarse irregular gold grains were hand picked from the panned heavies obtained by washing the excavated wall rock materials of the quartz veins which are composed of powdery latente ± kaolinite ± quartz. The gold grains display pitted, fractured, striated, wavy surface and occasional smooth contour pattern. The gold content of the quartz veins and latentic wall rocks vanes widely from < 1 ppm to 9 ppm SEM-EDS and microprobe analytical results of four gold grains reveal contrasting chemical characters. One gold gram exhibits nmward increase in fineness value indicating that silver has been preferentially leached out by supergene fluid. This grain possibly represents the residually concentrated hypogene gold. The other gold grains do not show chemical gradients within the domain of individual gram and formed by precipitation from supergene fluids.

Keywords

Gold, Supergene Mineralisation, Vein Quartz, Latentcs Fineness, Gopur, Orissa.

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