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

P. B. V. Subba Rao ¹, B. P. Singh ¹, P. B. Gawali ¹

Affiliations
1 Indian Institute of Geomagnetism, Colaba, Mumbai 400 005, IN

Abstract

Ocean bottom magnetometer (OBM) investigations were made across the Ninetyeast Ridge in the Bay of Bengal and geomagnetic field variations were recorded for a period of about one month. Analysis of data indicates that the thickness as well as resistivity of the oceanic crust/upper mantle reduces from 17 - 14 km and 439 - 308 Ohm-m respectively, as one moves from the Bay of Bengal to the Andaman arc region. The highly conducting Andaman arc region may have formed due to subduction related processes at the Andaman trench.

Analysis of OBM data collected earlier across the Barren Island in the Andaman Sea indicates the presence of two conductivity zones, at 17 - 27 km and 80 - 100 km depth. The enhanced conductivity at a shallow depth may be due to the conducting material/magma that has been emplaced by upwelling of the mantle material at the tectonic zone. The thickness of this material increases from north to south of the Barren Island and seems to concentrate the induced currents within the island. The enhanced conductivity at greater depths may be due to the H₂O and CO₂, that may be released by metamorphic reactions of the suhducting lndian plate beneath the Burmese plate.

Keywords

Geophysics, Ocean Bottom Magnetometer Investigations, Oceanic Crustal Structure, Partial Subduction, Low Resistivity Layer, Andaman Sea, Bay of Bengal.

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B. P. Singh ¹, B. K. Fotedar ¹, A. S. Rao ¹

Affiliations
1 Post Graduate Department of Geology, Jammu University, Jammu, IN

Abstract

The importance of the sandstones of Murree Group is becoming more and more due to the possibilities of occurrence of hydrocarbons. It is evident from the petrographic and geochemical studies that these sandstones are of sublitharenite type. Probably low to medium grade metamorphic, intermediate to acid igneous and preexisting sedimentary rocks were sources for these rocks. A cratonic near-shore depositional environment is suggested for these sediments. The palaeoclimatic conditions were mild as indicated by their mineralogy.

Keywords

Petrology (Sedimentary), Geochemistry, Sandstone, Murree Group, Jammu, Kashmir Himalaya.

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B. P. Singh ¹, C. S. Sudan ¹

Affiliations
1 Department of Geology University of Jammu, Jammu - 180 004, IN

Abstract

Trace fossils are found in the lower Siwalik rocks at Mansar and Jhajjar Kotli. The trace fossils are identified as Thalassinoides and Imbrichnus. It is interpreted that these fossils were developed in flood plains.

Keywords

Palaeontology, Trace Fossils, Siwalik Rocks, J&K, Himalaya.

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B. P. Singh ¹, U. Raval ²

Affiliations
1 Department of Geology, Banaras Hindu University, Varanasi - 221 005, IN
2 Hyderabad, IN

Abstract

No Abstract.

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S. K. Acharyya ¹, B. P. Singh ², J. S. Pawar ², Mithila ²

Affiliations
1 Dept Geol. Sci. , Jadavpur Univ , Kolkata - 700032, IN
2 Postgraduate, Department of Geology, University of Jammu, Jammu - 180 006, IN

Abstract

No Abstract.

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B. P. Singh ¹, J. S. Pawar ¹, Mithila ¹

Affiliations
1 Postgraduate Department of Geology, University of Jammu, Jammu - 180 006, IN

Abstract

The sedimentary structures in the bauxite deposits of the Jammu area are suggestive of a reworked bauxite precursor. Trace elements and REE concentrations show that the precursor bauxite originated from the weathering of basalt. It means that the bauxite forms a part of the earliest interval of the Himalayan foreland sedimentary sequences.

Keywords

Bauxite, Reworked Basalt, Geochemistry, Sedimentary Structures, Jammu Area, Jammu and Kashmir.

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B. P. Singh ¹, S. P. Singh ¹, H. K. Sachan ²

Affiliations
1 Postgraduate Department of Geology, University of Jammu, Jammu - 180 006, IN
2 Wadia Institute of Himalayan Geology, 33, Gen Mahadeo Singh Road, Dehra Dun - 248 001, IN

Abstract

The Kashmir and Chamba sub-basins of the Proto-Tethys were the sites of wide spread evaporitic deposition along the northern most part of the Indian passive continental margin during the Neoproterozoic. The evaporite lithologies of the Kashmir sub-Basin in the form of layered gypsum and nodular gypsum show deformational features and largely, secondary textures. Evidence of anhydritization and compaction/deformation is present in the form of anhydrite porphyrotopes, alignment of the crystals in a plane (recrystallization) and flowage layers (the result of plastic deformation). The original sulphate precipitates have passed through stages of burial diagenesis, metamorphism and exhumation, with formation of alabastrine and porphyrotopic sulphate. The exhumation of the sulphate sequence resulted in the development of overgrowths, dissolution along the relict anhydrite crystal boundaries, and the formation of lenticular gypsum crystals.

The Chamba sub-Basin contains a more complete example of evaporite sedimentation including carbonates, sulphate and chloride sedimentation. The sulphate sequences here show alabastrine, porphyrotopic and ameboid textures suggesting dehydration and rehydration reactions simlar to Kashmir sub-Basin. The fibrous satin-Spar gypsum occurring in the fractures of the carbonates most likely formed by the gypsum-Saturated brine released from dissolution and reprecipitation of near surface sulphate evaporites.

The rock salt in the Chamba sub-Basin is comprised of banded halite together with variable amount of clay and other impurities. The halite consists of interlocking crystals with zoning and irregular internal outline due to burial and subsequent recrystallization. The ragged outer edges and coigns of the zoned crystals, and brecciated texture are suggestive of groundwater dissolution during exhumation.

The microthermometric experiments on single-Phase fluid inclusions occuring in the crystals demonstrate that fluid inclusions were formed around 45°C, the temperature at which anhydrite rehydrated to gypsum and halite reprecipitated during exhumation.

Keywords

Evaporites, Diagenesis, Neoproterozoic, NW Lesser Himalaya, India.

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B. P. Singh ¹, A. K. Srivastava ¹

Affiliations
1 Department of Geology, Banaras Hindu University, Varanasi - 221 005, IN

Abstract

Late Paleocene-middle Eocene Subathu Formation represents the earliest deposits of the western Himalayan foreland basin. A large part of this formation is comprised of impure limestone and grey shale intercalations. The limestones contain sole marks, intraformational conglomerates, hummocky cross stratification and wave ripples. The occurrence of sole marks suggests that they are developed by the unidirectional currents at the initial phase of the storm that resulted erosion and subsequent deposition. The intra-formational limestone conglomerate also suggests erosion of the earlier deposited limestone hard grounds as a consequence of storm associated transgression. The hummocky cross stratification formed by the oscillatory flows during the long-shore littoral drift. The depth of formation of the hummocky cross stratified limestone facies was less than 40 m and most likely deposited between shore-face to backshore regions of the gulf similar to present day Persian Gulf. The identification of deeper facies (shelf facies) from Pakistan and coastal facies from India suggest that the gulf was open from the west and closed from the east.

Keywords

Hummocky Cross Stratification, Tempestites, Himalayan Foreland Basin, Subathu Formation, Northwest Himalaya.

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B. P. Singh ¹, S. K. Tandon ²

Affiliations
1 Department of Geology, University of Jammu, Jammu - 180 006, IN
2 Department of Geology, University of Delhi, Delhi - 110 007, IN

Abstract

Calcretes occur commonly in both Quaternary and pre-Quaternary continental and marginal marine sequences, and are generally considered as indicators of seasonal, aridlsemi-arid climatic conditions. The marginal marine and continental sedimentary basins of the Himalaya and the Phanerozoic Gondwana basins are analysed here to evaluate the possibilities of calcrete and palaeosol occurrences in them. A compilation of the known occurrences of calcretes and related palaeosols in pre-Quaternary and Quaternary sequences of India is also given.

The importance of calcretes and their evaluation in the Himalayan foreland for obtaining insights on Cenozoic climates is highlighted. Possibilities of future studies on calcretes and related palaeosols include: (a) the application of gradualistic pedofacies model in the well developed alluvial sequences of the Siwalik Group and the Gondwana Supergroup, (b) the identification of lowstand systems tract in the marginal marine basins of India, and (c) understanding the directions of climate changes in the Indian stratigraphic record.

Keywords

Calcretes, Palaeosols, Phanerozoic Stratigraphic Record, India.

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C. S. Sudan ¹, B. P. Singh ¹, U. K. Sharma ¹

Affiliations
1 Department of Geology, University of Jammu, Jammu - 180 006, IN

Abstract

The Murree Group is a cyclic succession of alternating argillaceous and arenaceous sediments. Trace fossils recovered from this succession include Chondrites isp., Cosmorhaphe fuchsi, Dendrotichnium cf. llarenai, Imbrichnus cf. wattonensis, Ophiomorpha isp., Planolites isp., Skolithos isp. and Thalassinoides isp. The ichnofauna suggests that the sediments of the Murree Group were deposited in coastal environments under brackish to fresh water conditions. The sandstone with Ophiomorpha was deposited in an estuarine channel whereas sandstone containing Costnorhaphe and small Thalassinoides was deposited on the levee-crest. Siltstones with Skolithos, Chondrites and Imbrichnus were deposited in the inter tidal zone whereas mudstones containing large Thalassinoides were deposited as mudflat 1 overbank sediments.

Keywords

Ichnofacies, Murree Group, Palaeogene, Jammu and Kashmir.

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B. P. Singh ¹, U. K. Shukla ¹, R. Bhatla ², D. Prakash ¹, A. S. Naik ¹, Kuldeep Prakash ¹, C. K. Singh ¹

Affiliations
1 Centre of Advanced Study in Geology and Banaras Hindu University, Varanasi - 221 005, IN
2 Department of Geophysics, Banaras Hindu University, Varanasi- 221 005, IN

Abstract

A National Seminar on “Geology and Geo-resources of the Himalaya and the cratonic regions of India” was organised by the Department of Geology, (Centre of Advanced Study), Kumaun University, Nainital during 10-12^th March, 2012. The Seminar was co-sponsored under the CAS Programme by the University Grants Commission, New Delhi; Department of Science and Technology, New Delhi; Uttarakhand State Council for Science and Technology, Dehradun; Kumaun University, Nainital; Censico International (P) Ltd., Agra. In all, 125 delegates from all over India actively participated in this national seminar.

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