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

R. C. Misra ¹, A. K. Singh ¹, J. B. Singh ¹

Affiliations
1 Department of Geology, University of Lucknow, Lucknow, IN

Abstract

No Abstract.

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B. D. Shukla ¹, A. K. Singh ¹, Prem Swarup ¹

Affiliations
1 Lucknow, U. P., IN

Abstract

Presence of scheelite is reported in the panned concentrates prepared from stream sediments collected from certain tributaries of Pindar river in Chamoli district. Studies carried out so far show that scheelite mineralisation is strata-controlled occurring within a garnetiferous-mica schist member. The host rocks are (i) green coloured epidote-amphibole rich rock (amphibolite?) and (ii) light coloured quartz-epidotecalcite bodies (boudins ?). Associated minerals are calc-silicates namely, actinolite, diopside, garnet and epidote; calcite is also present mainly in boudins, The garnetiferous schist member has been traced in both the limbs of Almora-Dudatoli syncline, along with the mineralised host rocks. The study indicates possibility of tracing extensive scheelite deposits in the crystalline nappe rocks of Himalayas. The deposits are believed to be of volcano-sedimentary origin, where tungsten is derived from submarine volcanic processes that took place during the deposition of limy argillaceous sediments.

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B. D. Shukla ¹, A. K. Singh ¹

Affiliations
1 U.P., Lucknow, IN

Abstract

No Abstract.

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Rajendra Singh ¹, R. Dhana Raju ², A. K. Singh ³

Affiliations
1 Atomic Minerals Division, Department of Atomic Energy, Hyderabad-500 016, IN
2 Atomic Minerals Division, Department of Atomic Energy, Bangalore-560 072, IN
3 Atomic Minerals Division, Department of Atomic Energy, Calcutta-700 026, IN

Abstract

A zirconium-rare earth (RE)-thorium-uranium fossil placer with about 60-84% heavy and resistant minerals is recorded in association with quartzite and metagreywacke of the Proterozoic Miri Group from the Boleng area in East Siang District of Arunachal Pradesh. The heavy minerals occur as thin layers with variable thickness of a fraction of a cm to a maximum of 12 cm. The mineralised rocks are hard, highly compact, very heavy (sp. gr. 3.96-4.66), massive (at places, banded) and exhbit clastic texture with rounded to subrounded and well sorted fine grains of heavy minerals pointing to a long distance of transportation. Mineralogically, it consists of 46-61% opaques (mostly Ti-hematite), 9-13% rutile, 3-9% cyrtolite, 0.7-4.5% monazite and 0.2-0.9% thorite, all set in 10-30% sericitic matrix. Chemically, it is markedly different from the widespread unconsolidated coastal and inland placers, and analyses about 43-62% iron oxides, 1.7-5.4% Zr0₂, 0.5-3.1 % (RE,Y)₂O₃, 0.1-0.5% ThO₂, and 0.01-0.9% U₃O₈. Chondrite-normalizcd REE-pattems show light REE enrichment and heavy REE depletion, with (Ce/Yb)_cn ratio of 9-10 and markedly negative Eu-anomaly (Eu/Eu: 0.18-0.22). Generally, consolidated placers (fossil placers) are monazite-rich, whereas unconsolidated placers are, zircon-rich and viewed in this light, the cyrtolite (zircon)-rich fossil placer from the Boleng area is a rare occurrence.

Keywords

Fossil Placer, Radioactivity, Boleng, Arunachal Pradesh.

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S. A. Farooqui ¹, A. K. Singh ¹

Affiliations
1 Directorate of Geology and Mining, Lucknow - UP, IN

Abstract

Incidence of Pt and Pd along with Au and Ag has been recorded in the serpentinised peridotites near Ikauna village(24°23'19"78°52'40"), Lalitpur district, Uttar Pradesh, which are in contact with gabbroic/dioritic and granitic rocks in the north and dioritic rocks in the south. The peridotite/serpentinised Talc-Actinolite schist zone has been traced for a distance of 15 km along the strike with an average width of 90m. Selected trench samples have shown Pt up to 1 71 ppm, Pd 2 02 ppm, Ir 0 62 ppm, Ru 0 07 ppm, Rh 0 30 ppm, Au 0 23 ppm, Ag 19 99 ppm, and NI 4800 ppm, Co 397 ppm, and Cr 4400 ppm. The zone continues eastwards and westwards with reduced width, but with incidence of these metals. Exploration is continuing for ascertaining existence of econormically viable mineralization.

Keywords

Platinum Minerallisation, Madaura Ultrabasic Complex, Ikauna Area, Lalitpur, Uttar Pradesh.

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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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S. C. Patel ¹, S. Behera ², A. Mohanty ¹, A. K. Singh ³, S. K. Patel ³

Affiliations
1 Department of Earth Sciences, Indian Institute of Technology, Powai, Mumbai, 400076, IN
2 Department of Applied Geology, Indian School of Mines, Dhanbad, 826004, IN
3 Orissa Mining Corporation Ltd., Bhubaneswar, Orissa, 751001, IN

Abstract

Cordierite-phlogopite dominated Mg-Al rich rocks occur as small enclaves at the Hatimunda hill near Junagarh in the Orissa sector of the Eastern Ghats belt. Peak mineral assemblages in these rocks included phlogopite, bronzite, kyanite (now reliet) and quartz/corundum. Sapphirine typically occurs as corona around corundum or in chisters along with corundum. The sapphirine is slightly more aluminous than the MgO:Al₂O₃:SiO₂ ratio of 7:9:3. Textural criteria and phase analysis in the model system MAS indicate the follwing reactions: Opx+Sil+Qtz+Crd; Opx+Sil=Crd+Crn; and Opx+Crn=Spr+Crd. A qualitative petregenetic grid shows that these reactions may be crossed in sequence along a decompressional P-T trajectory. The rocks preserve textural evidence of formation of sapphirine, at least in part, from phlogopite and sillimanite. P-T conditions for peak metamorphism were 700-800° C and > 8kbar based on the stability field of mineral assemblages. Texturally, early kyanite and late sillimanite indicate that the decompression is possibly part of a clockwise P-T path. This interpretation is supported by the occurrence of Mg-rich garnet (X_prp + 0.47) in the amphibole-dominated Mg-Al rich schist of the neighbouring Jilindara area.

Keywords

Sapphirine, Cordierite, Phlogopite, Relict kyanite, Decompression, Eastern Ghats.

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B. Nayak ¹, A. K. Singh ², A. K. Upadhyay ¹, K. K. Bhattacharyya ¹

Affiliations
1 National Metallurgical Laboratory, Jamshedpur - 831 007, IN
2 Wadia Institute of Himalayan Geology, 33, GMS Road, Dehradun - 248 001, IN

Abstract

Lower Gondwana coal from Garu-Gensi area in the West Siang district of Arunachal Pradesh in the Eastern Himalayas have been characterized with respect to their maceral constituents, mineral matter, ash composition, sulphurand trace-element contents. These are low-rank bituminous coals (V₀ = 0.64) and their vitrinite content is about 60%. A first hand data with respect to twenty one trace-elements are reported. Our data indicate that these Lower Gondwana coals of extra-peninsular region are richer in terms of their trace-element content when compared with their counter parts of peninsular India.

Keywords

Lower Gondwana Coal, Trace Element, Eastern Himalaya, Arunachal Pradesh.

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A. K. Singh ¹, J. N. Singh ¹

Affiliations
1 Basin Studies Division, K.D.M.I.P.E, ONGC Ltd., Kaulagarh Road, Dehradun - 248195, IN

Abstract

The paper defines the Pre-Tertiary stratigraphy of the Ganga Basin which is concealed beneath the thick cover of Cenozoic sediments. The sub-surface structural configuration is characterised by development of four major depressions, separated by transverse uplifts. Ganga Basin represents two main stages of geological evolution: a pre-collisional (Pre-Tertiary) stage consisting mainly of Proterozoic and Gondwana sediments, and a post-collisional (Tertiary) stage representing the Siwalik molasse. The Pre-Tertiary succession is classified into four mega sequences; three of these representing Precambrian sediments, comprising of Aravalli, Bijawar, Delhi and Vindhyan systems and one megasequence corresponding to Gondwana system in the Pumea Depression.

Keywords

Sequence Stratigraphy, Sedimentology, Ganga Basin.

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