013983   Mukhopadhyay D;Senthil Kumar P;Srinivasan R; Bhattacharya T;Sengupta P (Department of Geology, University of Calcutta, 35, Ballygunge Circular Road, Calcutta-700 019) : Tectono-metamorphic pattern in the eastern sector of the Palghat-Cauvery lineament. Indian Mineralogist 2000, 34(1), 20-1.

013982   Mohanty P R;Bhattacharya B B (Department of Applied Geophysics, Indian School of Mines, Dhanbad-826 004) : Detection of some typical structural and stratigraphic features in coal seams using seismic modelling. Indian Miner 2000, 54(1-2), 85-98.

In geophysical exploration for coal, the presence of the target is generally known unlike the petroleum exploration. High Resolution Reflection Seismics (HRSS) is extensively used in the exploration of coal to map the geological features like faults, wash-outs, wedge-outs and igneous intrustions, etc. The study deals with the interpretational aspects of HRRS data through seismic modelling. Several zero-offset sections have been generated through 2D acoustic modelling for some typical features encountered in the Raniganj Coalfield. It is observed that the detectability of these features depends on the frequency content of the source wavelet, depth and the geometry of the target.

013981   Khorana R K;Dhir N K;Jayapaul D (Geological Survey of India, , Faridabad-121 001) : Preliminary appraisal of gold mineralisation at Tosham, district Bhiwani, Haryana. Indian Miner 2000, 54(1-2), 127-9.

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013980   Jayananda M;Harish Kumar S B;Sadakshara Swamy N (Department of Geology, Bangalore University, Jnanabharathi, Bangalore-560 056) : Crustal accretion patterns on the late archaean eastern Dharwar craton : Kuppam - toppur section. Indian Mineralogist 2000, 34(1), 17-18.

013979   Jayalakshmy K V;Raveendran O;Sreeja S (National Institute of Oceanography, Regional Centre, Kochi-682 014) : Seasonal variation of the environmental parameters along Fort Cochin beach. Fish Technol 2000, 37(2), 98-108.

Monthly observations on heterotrophic bacteria, organic carbon, temperature, salinity, dissolved oxygen, inorganic phosphate, nitrate, nitrite and ammonia from surface water and from water table level during high tide, mid tide and low tide were carried out in the fort Cochin beach for a period of one year. Also, monthly observations on heterotrophic bacteria, organic carbon and temperature were carried out for the same period from sand during the three tidal levels at surface and water table level. The study showed that orgaic carbon in sand controlled the bacterial population to a great extent during fhigh tide at surface and during low tide at water table level. Step-up multiple regression analysis showed that in water the interaction effect of inorganic phosphate and ammonia and that of ammonia and temperature were the most important parameters controlling the bacterial production whereas in the sand at the surface, temperature-organic carbon interaction effect was the controlling parameter. The results of the Q-mode analysis are also presented.

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013978   Jain A K;Manickavasagam R M;Singh S;Devaraju J;Lal N (Department of Earth Sciences, University of Roorkee, Roorkee) : Geodynamics and exhumation of the south Indian granulite terranes : role of intra - continental shear zone across Kanyakumari - Kuppam transect. Indian Mineralogist 2000, 34(1), 8-16.

013977   Ghosh S (Geological Survey of India, , Unit VIII, Nuapalli, Bhubaneswar-751 012) : Muzaffarpur plessitic octahedrite - an example of post-shock superposed shear deformation in iron meteorite. Indian Miner 2000, 54(1-2), 69-78.

Muzaffarpur is a unique Plessitic Octahedrite with signatures of shock deformation, shear deformation and associated thermal alteration. The primary cooling took place between 900°C and 350°C at a slow rate, nearly 6°C/10⁶ years. Shock deformation on Muzaffarpur was limited to a very mild plastic state only (up to 130 kb). Highly deformed neumann lines do indicate the post-shock shearing activity. An imprint of superposed shear deformations, at least of two generations, is distinct in Muzaffarpur and the direction of shearing stress varied. In the beginning, deformation was in a plastic stage and finally continued to a stage of developing slip planes and microcracks. Shear deformation is also responsible for the alteration of duplex plessite to streaky and feathery plessite and H_v-data confirm the whole episode. Thermal alteration associated with both shearing and shock deformation resulted in the formation of coarser finger plessites close to the shear zones with development of micro-widmanstatten pattern in general and recrystallisation of kamacites in particular. Temperature of thermal alteration is estimated to range between 300°C and 750°C.

013976   Ghosh Roy A K;Adhikari B;Pant N C; Mukhopadhyay G (Petrology Division, E R Geological Survey of India, Calcutta-700 016) : Tetraferriphologopite from carbonatite of Temarporpamar shear zone, Purulia district, West Bengal. Indian Miner 2000, 54(1-2), 113-18.

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013975   Dasgupta S;De U K (Atmospheric Science Research Group, Environmental Science Programme, F, Jadavpur University, Calcutta-700 032) : Markov chain models for pre-monsoon thunderstorm in Calcutta, India. Indian J Radio Space Phys 2001, 30(3), 138-42.

Markov chain models of first, second and third order have been used to provide a probabilistic description of pre occurrence of the thunderstorm phenomenon in the pre-monsoon season (March-May) in Calcutta (India). The analysis is based on the relevant data for the 10-year period 1985-94. Use of Akaike's information criterion (AIC) reveals that the Markov chain of the third order is perhaps the model that describes best the phenomenon. This finding is also supported by actual verification of the fact that the Markov chain of third order simulates the observed data best. Besides, the time independent behaviour of the chain has also been studied with the help of the steady state probabilities. The theoretical values of the mean recurrence time for thunderstorm and fair weather days hence obtained are in close agreement with the observed data.

013974   Chetty T R K;Narayana B L;Bhaskar Rao Y J (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Structural cross-section along Krishnagiri-palani geotransect, southern granulite terrain, south India. Indian Mineralogist 2000, 34(1), 4-7.

013973   Chattopadhyay A K;Mishra R N (Geological Survey of India, , Calcutta-700 064) : Ghugra lead and zinc deposit of Ajmer : a case study on broad-based exploration confidence. Indian Miner 2000, 54(1-2), 57-68.

The basemental deposit at Ghugra (23°31'00"N:74°30'08"E), at the north-eastern outskirt of the city of Ajmer in Rajasthan, is a case of sediment-hosted lead-zinc mineralisation of Mid. to Upper Proterozoic age. The stratigraphy is represented by quartzite, calc-silicates and metapsammopelites exposed from foot-wall to hanging-wall side, of which calc-silicates accommodate significant concentration of lead-zinc mineralisation. Sphalerite and galena are the main mineralised components while chalcopyrite is a subordinate association. 2,934 core samples drawn from a total of 4,559.60 m core drilling in 29 drill holes from the data array for grade and reserve estimations and ultimate metal balance studies for the Ghugra basemental deposite, Rajasthan. In each of the estimates, statistical reasoning and treatment have come out with minimal, optimal and maximal values as per longnormal distribution and were tested both for the grade pattern as also for the reserve distribution point estimates. Although the average grades show a reliability of ± 83% to 85% at 68% confidence level, there seems to be an increase in estimation errors of the order of ± 24% to 36% at 95% confidence level for combined permutations with different cut-off grades. The categorisation of reserves at C1 and C2 stand well for the error limit thus envisaged. Geological ore reserves, however, show much wider ranges, in the lodge type of basemetal deposits. Variation statistics in grade tonnage curves point to a recommendation of 11 million tonne with 5% Pb+Zn as the most natural expectations, with 0.25 million tonne of metallic lead and 0.3 million tonne of metallic zinc as considerate and judicious geological expectations.

013972   Calla O P N;Hannan I (International Centre for Radio Sciences, , `OM-NIWAS' A-23 Shastri Nagar, Jodhpur-342 003) : Estimation of scattering coefficient of dry and wet soil with different moisture content at microwave frequencies. Indian J Radio Space Phys 2001, 30(2), 106-11.

Microwave backscattering of the soil depends on its dielectric constant, which varies with change in the moisture content of the soil. The knowledge of the variability of the soil moisture is important for agriculture. With the database of the dielectric constant of a typical soil of Rajasthan, the computation of the scattering coefficient has been carried out using the perturbation model. The database of the estimated scattering coefficient at microwave frequencies (2-20 GHz) for dry and wet soil with different moisture contents has been generated. This will be useful for microwave remote sensing of soil, which will provide additional input for agriculture.

013971   Bhuyan P K;Kakoty P K (Department of Physics, Dibrugarh University, Dibrugarh-786 004) : Modelling study of Indian low latitude ionosphere. II. Results and comparison with SROSS-C2 satellite data. Indian J Radio Space Phys 2001, 30(2), 66-71.

A time-dependent model developed for the Indian low latitude ionosphere (Part I) is used to calculate the O⁺ and H⁺ ion density distribution within ±15° geomagnetic latitude. The calculations are performed along magnetic field lines from a base altitude of 120 km in the northern hemisphere to the same altitude in the southern hemisphere for solar minimum equinoctial conditions. It is found that the modelled O⁺ and H⁺ concentration are in reasonable accord with the observations made from Indian SROSS-C2 satellite at a height of 0<126> 500 km over India during the period August 1995-July 1996

013970   Bhuyan P K;Kakoty P K (Department of Physics, Dibrugarh University, Dibrugarh-786 004) : Modelling study of Indian low latitude ionosphere. I. Description of the model. Indian J Radio Space Phys 2001, 30(2), 59-65.

On the basis of continuity equation for the ionospheric F-region, a time dependent model for the Indian low latitude ionosphere is proposed. Photoionization production, recombination, thermospheric wind and electromagnetic drifts have been taken into account for solving the continuity equation for the major ion species O⁺ and H⁺. The numerical scheme used for solving the continuity equation is given and the selection of input parameters to the numerical model is discussed. The model can be used for the investigation of the influence of different parameters such as neutral wind, solar radiation flux, electro-magnetic drift, etc. on the ionospheric processes.

013969   Bhaskar Rao Y J;Dayal A M;Vijaya Kumar T; Pantulu G V C;Narayana B L (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : New SM/ND model ages of infracrustal high-grade gneisses along Krishnagiri-palani geotransect, southern granulite terrain, South India. Indian Mineralogist 2000, 34(1), 1-3.

013968   Ali S A (Department of Geology, Aligarh Muslim University, Aligarh-202 002) : Bedding characteristics of conglomerate of Debari group, Aravalli supergroup, Udaipur district, Rajasthan. Indian Miner 2000, 54(1-2), 79-84.

Deals with the study of phenoclast segregation factor and lenticularity index of the Debari conglomerate (2.5 Ga) from Jaisamand area. The study reveals that the phenoclasts correspond to wave-worked and intermediate current-dominated regimes. The fabric isotropy is possibly appositional and brought about by wave dynamics during the deposition of the Debari conglomerates.

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013026   Vinayaka S;Govindaiah S;Pathan A M (Department of Studies in Geology, University of Mysore, Manasagangotri, Mysore-570 006) : Textural features of chromite and V-Ti magnetite layers in the ultramafic-mafic complex of Nuggihalli schist belt, Dharwar craton, India. Indian Mineralogist 1999, 33(1), 113-23.

Layered complex consisting of serpentinized dunite, peridotite, metapyroxenite, meta-gabbro (amphibolite) and anorthosite have been emplaced into the metasedimentary rocks of the Sargur group in the Nuggihalli schist belt, Dharwar craton. The chromitite layers are confined to ultramafic rocks whereas the V-Ti magnetite layers to the gabbro-anorthosite suite of rocks. Chromite grains form either a compact granular mosaic or a characteristic cumulus texture with minor interstitial serpentine after olivine. Chromite exhibits occluded silicate and chain textures. The grain size of chromite is variable; the early formed chromite grains have corroded boundaries indicating reactions with the surrounding liquid with which they were in contact. Chromite also exhibits cored clot texture in which the fine grained chromite grains are disseminated and surrounded by coarse grained chromite grains. The core consists of silicates indicating a primary igneous texture.

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013025   Vannappa B;Govindaiah S;Kariyanna H (Department of Geology, Dr. Ambedkar Institute of Technology, Bangalore-56) : Hogbomite in the V-Ti magnetite ores of Durgagudda - Upper Kaneri layered complex, North Kanara district, Karnataka. Indian Mineralogist 1999, 33(1), 103-11.

Durgagudda - Upper Kaneri layered ultramafic - mafic complex emplaced into the late Archaean Dharwar greenstone - granite terrain. The layered complex, consisting of pyroxenites, gabbroic anorthosite, anorthositic gabbro, gabbro, magnetite-gabbro together with V-Ti magmetite layers, is emplaced into a deep seated fault zone cum axial trace of F₂ fold deformation and extending over a strike length of about 30 to 32 kms along NF-SW direction with a width of about 0.5 to 2.0 kms from Durgagudda and upto the east of Vogeli.

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013024   Ugarkar A G;Vasudev V N (Department of Geology, Karnatak University, Dharwad-580 003) : Geochemistry and tectonic setting of archaean gold bearing metavolcanic rocks of Mangalur schist belt, eastern Dharwar craton, Karnataka. Indian Mineralogist 1999, 33(2), 1-17.

Mangalur schist belt is dominantly composed of metavolcanic rocks which host gold mineralisation. Major and trace element data for the least altered metavolcanic rocks indicate that they are low-K Fe-rich tholeiitic basalts and in this respect compare with other gold bearing low-K tholeiitic basalts of Kolar, Ramagiri and Hutti belts of the eastern Dharwar terrain. The presence of granite-gneiss pebbles in polymict conglomerate points to the existence of a granitic provenance. Geochemical feature suggest a rifted intra-arc environment as the most favourable tectonic regime for the development of Mangalur schist belt.

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013023   Ugarkar A G;Deshpande M P (Department of Geology, Karnatak University, Dharwad-580 003) : Lithology and gold mineralisation of Gadag gold field, Dharwar craton: evidences for epigenesis of gold in diversified host rocks. Indian Mineralogist 1999, 33(1), 37-52.

Gadag gold field is characterised by a wide range of volcano-sedimentary lithounits. The regional metamorphism has resulted in greenschist to low amphibolite facies mineral assemblages. The metavolcanics have oceanic, Fe-rich tholeiitic affinity. The metasediments have K₂O/Na₂ O ratios less than 1 and have higher FeO/MgO ratios (<60>3).

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013022   Trehan S P (Central Potato Research Station, , Model Town P.O., Post Bag No. 1, Jalandhar-144 003) : Mineralization of nitrogen from cattle slurry decomposing in soil. J Indian Soc Soil Sci 2000, 48(3), 463-8.

Incubation experiment was conducted over a period of one year to find gross and net mineralization of N from cattle slurry decomposing in soil at 25°C and 50 per cent water holding capacity moisture. Labelled ammonium sulphate and fresh cattle slurry with its inorganic fraction labelled with ammonium sulphate were used to follow the transformations of N. Measurements were made at different intervals for NH₄-N, NO₃-N, organic-N clay fixed -N and gross mineralization and immobilization of N were calculated. There was extensive mineralization and immobilization of N in a slurry- amended soil and there was no net mineralization of N over about 30 days because rates of both the reactions were equal. Steady net mineralization of slurry organic N started after the rapid phase of turnover at about 1-2 months. The amount of N mineralized from the organic fraction of slurry in one year was 49.1 per cent of the organic N in slurry and net mineralization was 26.3 per cent of the organic N in slurry.

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013021   Tareen J A K;Ganesha A V;Basavalingu B; Keshava Prasad A V (Department of Geology, Manasagangotri, University of Mysore, Mysore-6) : Cordierite formation during metamorphism of pelitic rocks: an experimental study of the assemblage 2Phl-6Sil-9Qtz - in the system K₂ O-MgO-Al₂O₃-SiO₂-H₂O. Indian Mineralogist 1999, 33(2), 34-46.

First appearance of cordierite in high alumina pelitic rocks marks the beginning of granulite metamorphism. The breakdown reactions of phlogopite to form condierite: have been studied in water saturated conditions in the temperature and pressure range of 650-900%C and 3-10 kbar respectively. Both Tuttle reactors and internally heated gas bomb were used. The boundary for the subsolidus breakdown to cordierite-K feldspar-vapour lies between 4 and 5 kbar with gentle positive slope. This experimental boundary is located at 500 bars and 1000 bars lower than the calculated boundaries has been reported.

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013020   Singh Y (Atomic Minerals Directorate for Exploration and Research, , Begumpet, Hyderabad-500 016) : Petrogenesis of brecciated and other precambrian rare metal pegmatites near Kawadgaon, Bastar district, Madhya Pradesh. Indian Mineralogist 1999, 33(1), 95-101.

The rare metal pegmatites, which were derived first from the surrounding peraluminous, S-type parent granites (2497 Ma), were brecciated due to an upward surge of the underlying more evolved pegmatite magma, representing unbrecciated pegmatites. Pronounced silicification, growth of numerous euhedral vug-filling quartz crystals and presence of miarolitic cavities suggest that brecciation of relatively older pegmatites took place under epithermal conditions. The brecciated pegmatites may be grouped under two categories: pre-hydrothermal breccia (formed by intrusive action of magma) and co-hydrothermal breccia (formed by outgrowth of hydrothermal activity).

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013019   Sharma U P;Gajapathi Rao R;Durg N L (Atomic Minerals Directorate for Exploration and Research, , Bangalore-560 072) : Pitchblende in the basement granite of Kaladgi basin, near Nidgundi, Bijapur district, Karnataka. Indian Mineralogist 1999, 33(1), 27-30.

Grab samples (n=7) of the peraluminous basement granite of the Kaladgi basin near Nidgundi have analysed 0.009-0.064% eU₃O₈, 0.005-0-091% U₃O₈ and 0.003-0.019% ThO₂, mainly due to the presence of pitchblende, that is reported for the first time from this area.

013018   Rao A V;Krishna Rao B;Govindaiah S; Sethumadhav M S (Department of Studies in Geology, Manasagangotri, University of Mysore, Mysore-570 006) : P-T conditions of metamorphism of the supracrustal rocks in the southern part of the holenarsipur schist belt and the genesis of the associated asbestos mineralization. Indian Mineralogist 1999, 33(2), 81-95.

Southern part of the Holenarsipur schist belt consists of Sargur group of supracrustal rocks, which are composed mainly of hornblende schists/amphibolites, pelites, rhyodacite and ultrabasic-basic intrusive complex (dunite, harzburgite, pyroxenite and gabbro - anorthosite and hornblendite). These rocks are intruded by Gunjur betta granite. Based on the mineral chemistry (EP.MA) data of the prograde mineral assemblages, it is inferred that the supracrustal rocks were subjected to upper amphibolite facies metamorphism at T <126> 600°C and P-5 - 7 Kbars.

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013017   Rao A T;Veeranarayan Rao B (Department of Geology, Andhra University, Visakhapatnam-530 003) : Temperature of metamorphism of the basic granulites around Addatigala and Devipatnam in the Eastern Ghats granulite belt, A.P.. Indian Mineralogist 1999, 33(2), 65-9.

Basic granulites around Addatigala and Devipatnam contain two pyroxenes, and are occasionally magnetite rich. The mineral chemical data obtained for co-existing pyroxenes indicate that they have attained equilibration around 700°C, subsequent to the peak metamorphic conditions.

013016   Ramamohana RAo T;Sairam K;Rao Y V (Department of Geology, Andhra University, Visakhapatnam-530 003) : Sedimentological and geochemical characters of the lower Gondwana rocks of Chintalapudi sub basin of the Godavari Valley of Andhra Pradesh. Indian Mineralogist 1999, 33(1), 151-68.

Comparative study of the sedimentological and geochemical characters of the sandstones of the Barakar formation (Later part of the Early Permean) and of the Kamthi Formation (Late Permean to Early Triassic) of the Chintalapudi sub-basin of the Godavari Valley reveals certain similarities and dissimilarities. The sandstones of both the formations are medium to coarse grained in size, very poorly sorted, very positively skewed and very leptokurtic. The C-M. Patterns reveal the differences between the two in rolling and bottom suspension - the Kamthi sediments were transported with greater turbulence and flow than the Barakar sediments. The Kamthi conglomeratic sandstone is radioactive 3 to 4 times the background. The Q-F-L diagrams show that the sandstones of the both are quartzose wackes and that the both of them derived the sediments from a provenance of the cratonic interior.

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013015   Prabhakara Rao A;Krishna Rao J S R;Ravi G S (Atomic Minerals Division, , Visakhapatnam-530 018) : Nature and mineral chemistry of chromite from Sittampundi complex, Tamil Nadu, India. Indian Mineralogist 1999, 33(1), 11-18.

Peninsular India is bestowed with chromite that occurs mostly in different geological formations, viz. Iron ore Series, Dharwars and Eastern Ghats in the states of Orissa, Bihar, Karnataka, Andhra Pradesh and Tamil Nadu. The chromite occurrence of Sittampundi, Tamil Nadu, in association with anorthosite, places it in an unique geological environment in India since other chromite bodies are associated with pyroxenite, peridotite, dunite, amphibolite and their altered products. Based on the ore characters, six varieties of ores have been identified in Sittampundi, viz., banded, coarse and hard, spotted pitted, soft/friable, lateritic and mylonitised. Chromite grains separated from representative samples of these have been chemically analysed, unit cell values calculated and the analytical results are interpreted and discussed. The data indicate that the Sittampundi chromite is significantly poor in Cr₂O₃ but rich in Al₂ O₃ and Fe₂ O₃ (total), and falls in a transitional type at the boundary of aluminium chromite and the chromian spinel fields. Spinel-type of chromite with stratiform nature is suggested for the Sittampundi chromite, that may be potential for Platinum Group Elements.

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013014   Patra A K;Cuttle S P;Jarvis S C;Scurlock R V (NO, Institute of Grassland and Environmental Research (IGER), Plas Gogerddan, Aberystwyth, Ceredigion SY23 3EB, UK) : Potential nitrogen mineralization in and short-term nitrification potential of soils from a permanent pasture and a recently cultivated grassland. J Indian Soc Soil Sci 2000, 48(3), 457-63.

Net potential nitrogen mineralization (PNM) and short-term nitrification potential (SNP) were measured at 3 depths (0-7, 7-14, 14-21 cm) in soils collected from adjoining permanent pasture and reseeded grassland at the Institute of Grassland and Environmental Research (IGER), Aberystwyth. Organic-C and total N concentrations varied little with depth in either soil. At the time of sampling in April 1996, NO₃^- -N of soils (0-21 cm depth) from the reseeded field (6.2 to 18 mg kg^-1 soil) were greater than those from the permanent pasture (2.4 to 3.6 mg kg^-1). Net PNM was higher in each layer in permanentgrassland, though in both pastures it was at a maximum in the top layer (0-7 cm) and decreased with depth. In contrast to net PNM, the SNP data revealed that reseeded pasture had almost three times higher nitrification activity than the permanent sward. In both soils, however, SNP varied little with depth . The moisture content varied little with depth but was higher in reseeded pasture than the permanent sward.

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013013   Parthiban G;Banakar V K (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Chemistry and possible resource potential of cobalt rich ferromanganese crusts from Afanasiy-Nikitin seamount in the Indian ocean. Indian Mineralogist 1999, 33(1), 125-32.

Samples of ferromanganese encrustations (Fe-Mn Crusts) dredged from the upper flank of the Afanasiy-Nikitin seamount, above the Carbonate Compensation Depth (CCD) in the Northern Central Indian Ocean (NClO) were analysed for Al, Fe, Mn, Ca, Ba, Cu, Ni, Co, Zn and V and found to be rich in Co (upto 0.88%). Mineralogically, the studied Fe-Mn crust samples contain poorly crystalline d-MnO₂, and minor amount of Carbonate Fluorapatite (CFA) and feldspars. The low Mn/Fe ratios (<60>), d-MnO₂ dominant mineralogy and the interelement associations show that these crusts are formed by slow hydrogenetic precipitation of colloidal Fe-Mn oxyhydroxides Fe, Mn, Co, Zn and V exhibit mutually strong positive association (r <62> 0.7) indicating their incorporation into the Fe-Mn crust during the hydrogenetic precipitation. The Al on the other hand, appears to be independent and diluant for hydrogenetic component. Therefore, the Al in the Fe-Mn crusts might be due to the presence of fine lithogenous detritus intermixed with hydrogenetic component. Another detrital indicator element `Ti', instead of showing the affinity to Al exhibits affinity towards hydrogenetic oxide elements suggesting a possible incorporation into Fe-Mn crust analogous to other transition metals.

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013012   Mallikharjuna Rao J (NO, National Geophysical Research Institute, Hyderabad-500 007) : Trace and REE compositions of garnets from Eastern Ghat granulite belt. Indian Mineralogist 1999, 33(2), 47-54.

Garnet a common mineral in the granulites of Eastern Ghat belt (EGG) is a potential source of REE. Trace element and REE studies of inclusion free and chemically unzoned garnets from the charnockites, basic granulites and leptynites of the EGG belt exhibit substantial variation in their REE and trace element contents. The observed variation in garnets can be correlated with the whole rock composition.

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013011   Maitra S (Centre for Studies in Resources Engineering, Indian Institute of Technology, Bombay, Mumbai-400 076) : Landforms and geomorphological classification of part of the upper Baitarani river basin. J Indian Soc Remote Sens 1999, 27(3), 175-84.

Geomorphological map is a very effective tool in management of natural resources and helps in various types of planning and developmental activities. In the study, geomorphological map for part of the upper Baitarani river basin was prepared using aerial photographs on 1:25,000 scale, satellite imagery in the form of IRS-IA false colour composites, generated from bands, 2,3,4 and SOI topographic sheets validated by ground truth. Since large part of the study area is inaccessible, remotely sensed data have played an important role in detailed mapping. The study area is mainly underlain by Precambrian rocks. Quarternary and recent formations are confined mainly to the river valleys. The criteria adopted for the identification and grouping of landforms of specific genetic type are the overall appearance (morphography), the shape/surface geometry (morphometry). The underlying geology, relief forming processes, and association of forms. The landform units as identified and delineated on the remotely sensed data are grouped under two genetic types, denudational and fluvial. Ten landform units, each having its own features, were identified under three geomorphic domains via. Hill, Piedmont and Plain.

013010   Kasipathi C;Padmavathi M V L;Srinivasa Rao K; Arjunudu K;Ravi C;Krishna C;Trinadha Rao P;Janardhana Rao K V (Department of Geology, Andhra University, Visakhapatnam-530 003) : Precious and semi-precious stone occurrences with Eastern Ghat formations, Visakhapatnam district, Andhra Pradesh. Indian Mineralogist 1999, 33(2), 23-33.

Long geological history of Eastern Ghats so far proved the occurrence of many rich metallic and non-metallic mineral resources and presently by precious and semi-precious stones. Pegmatitic intrusives discordant to the principal members of the Eastern Ghat formations brought to light valuable precious and semi-precious stones recently in parts of Visakhapatnam District, Andhra Pradesh. The geology, nature of occurrence of the gemstones, the pattern of the disposition of the body as in-situ and colluvial bodies in brief are presented in order to appraise the gemstone scenario, for a latest geological perspective of the region.

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013009   Kariyanna H;Khonglah M A (NO, Chinmayee, Upparahalli Extension, Tumkur-572 102) : Occurrence of titaniferous/vanadiferous magnetite in archaean gneisses, West Khasi Hills District, Meghalaya state, Northeast India. Indian Mineralogist 1999, 33(1), 169-75.

Titaniferous/vanadiferous magnetite is being reported for the first time by the authors in West Khasi Hills District, Meghalaya Plateau. It occurs as a band within the remobilised and reactivated Archaean gneisses of West Khasi Hills District. The exposure of titaniferous/vanadiferous magnetite band is found five kilometres east or Rambrai (25⁰ 39'24' -91⁰ 15'22') and is in intimate association with ferrogabbroids emplaced within the remobilised Archaean gneiss. This band trends in N-S direction is 15-20 metres in width and is abvout 200-250 metres in length. The XRD analysis clearly typifies that it contains essentially magnetite minor ilmenite, good amount of haematite and traces of quartz and mica. Ti/V magnetite is crystalline, granular and steel grey to brown in colour.

013008   Hegde V S;Chavadi V C (NO, S.D.M. College of Engg and Technology, Dharwad-580 002) : Geochemistry of pelitic sediments of Arabail area, Yellapur taluk, Uttara Kannada District, Karnataka. Indian Mineralogist 1999, 33(1), 53-67.

Petrogenesis of pelitic sediments associated with Limestone-Iron-Manganese Formations of Chitradurga Group occuring around Arabail area of Yellapur taluk is presented. These pelitic sediments are rich in Si, Al and K compared to North American Shale Component (NASC), while their K₂O/Na₂O ratio is low (1.52-2.46), and is comparable to the platformal type pelites of South-Africa. The pelites show moderately high concentration of Cr (112-163 ppm) and Ni (62-117 ppm). Their Chemical Index of Alteration (CIA) range (60-63%) is less compared to the pelites of Witwatersrand Supergroup and Transval and Ventersdorp Supergroup of South-Africa. The geochemical data reveal predominantly granitic/granodiorite provenance, moderate chemical weathering and deposition in a platformal tectonic setting. The pelites have undergone low grade greenschist facies of metamorphism at 2-3 K-b and temperature around 350°C.

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013007   Hanamgond P T;Chavadi V C (Department of Geology, G S Science College, Belgaum-590 006) : Sediment movement as inferred from texture and heavy minerals, along Belekeri Bay beaches, west coast of India. Indian Mineralogist 1999, 33(1), 69-81.

Textural and heavy mineral assemblages of the Belekeri Bay (Mudga and Harwada) beach sediments were studied. The textural and heavy mineral assemblages of beach sands were studied in order to understand the spatial, seasonal and longshore distributions, source of the sediment (provenance) and the sediment movement. The sediments decrease in their size from Harwada towards Mudga (northerly) with improvement in sorting, indicating sediment movement in that direction. CM patterns for the sediments of these beaches indicate that, majority of the sediments are transported as graded suspension, except for Harwada beach where, the sediments are transported as rolling. From the study of CM patterns, the dominance of medium sand; and platykurtic nature of sediments at Harwada beach, compared to the dominance of fine sand and mesokurtic nature of sediments at Mudga beach, indicate that Harwada beach experiences high energy environment. Longshore variability of the heavy mineral assemblages is considerable. Distribution of opaques, rutile, tourmaline and zircon reveals that their concentrations are high in the southern end (Harwada) and that decreases towards north (Mudga). The heavy mineral assemblage reveals the mixed provenance of igneous and metamorphic rocks with reworked sediments.

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013006   Hanagodimath R S;Nadagouda D B;Mannikeri M S (Department of Geology, Karnatak University, Dharwad-580 003) : Carbonate rocks from Kudrekanive-Huliyar area, Tumkur district, Karnataka. Indian Mineralogist 1999, 33(1), 83-94.

Carbonates of Kudrekanive-Huliyar area include calc-schists, limestones, ankerites and dolomites. Chemically these rocks cover a wide range from almost pure clacite and dolomite-ankerite to Mg limestones, shaly/cherty limestones and dolomites/ankerites. In trace elements, these rocks are much depleted when compared to the carbonatites. Available evidences indicate overall primary chemical sedimentary deposition of the carbonates in barred basin with gradual rise in salinity, pH, temperature and Mg:Ca ratio of the environment. Dolomitization seems to have acted to a very limited extent.

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013005   Hanagodimath R S;Chavadi V C;Mannikeri M S; Khanadali S D;Ugarkar A G (Department of Studies in Geology, Karnatak University, Dharwad-580 003) : Volcanism in the northern part of the Dharwar shimoga schist belt, Karnataka. Indian Mineralogist 1999, 33(2), 18-22.

Detailed field and petrographic investigations have brought to light the evidences of wide spread volcanic activity in the form of pillowed basalts and andesitic flows in the vicinityof Dharwad city and thick bands of pyroclastic andesites and basalts around Bailhongal town which form the northern part of the Dharwar-Shimoga schist belt. Considering the gross lithology of the area under investigation, the occurrence of metavolcanic rocks fits well into the tectonostratigraphic models suggested by earlier workers.

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013004   Gupta L N;Ravindra Kumar;Turki S K (Department of Geology, Panjab University, Chandigarh) : Petrochemistry and mineral chemistry of the jutogh metabasites of south-eastern Himachal Pradesh, lesser Himalaya, India. Indian Mineralogist 1999, 33(1), 133-49.

Metabasic bodies occurring as dykes and sills in the jutogh Group (Precambrian) have been recorded in the Shimla district of Himachal Pradesh. The metbasics comprise quartz-amphibolite, garnet-amphibolite, epidiorite and metadolerite. Geochemistry of metabasics indicates that the rocks belong to tholeiitic series which have undergone middle order differentiation. Amphiboles in metabasics belong to calcic group and have been classified into ferrotschermakitic hornblende, edinite and ferroan pargasitic hornblende. Plagioclases contain nearly 23 to 35 mol% of anorthite, and negligible amount of orthoclase. They are considered to have crystallised between 900° and 1000°C at 5 kbar pressure. Only a little variation in anorthite content of plagioclasses indicate that near chemical equilibrium has been attained. Garnet contains 52% almandine, 14% spessartine, 5% pyrope and 29% grossular molecules. Crystallisation of garnet was controlled by the bulk composition and high pressure. Sphene crystals are essentially in ideal stoichiometric phase. Ilmenite is of crichlonite variety and is similar in chemical composition to common ilmenite found in fayalite ferrogabbros.

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013003   Gupta L N;Dhar B L;Kochhar N (Department of Geology, Punjab University, Chandigarh) : Petrochemical study of reported "ash beds" from the Nagrota formation (upper Siwaliks), Jammu region. Indian Mineralogist 1999, 33(2), 55-64.

Volcanic ash/tuff layers reported from the Nagrota Formation of Jammu region have been reinvestigated. These beds do not contain any identifiable pyroclastic material. On the otherhand, they are composed of components viz. clayey groundmass schistose rock fragments, mineral fragments of quartz, feldspar and biotite, and isolated heavy minerals embedded in the groundmass.

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013002   Dutta D;Sah K D;Reddy R S;Anil Kumar K S; Koyal A (National Bureau of Soil Survey and Land Use Planning, Regional Centre, , Hebbal, Bangalore-560 024) : Soil organic carbon storage in different landforms of South Deccan Plateau Andhra Pradesh. J Indian Soc Soil Sci 2000, 48(3), 447-50.

Thirty-two soil profiles and 44 surface soil-sites in the cultivated areas representing five landforms in South Deccan Plateau of Andhra Pradesh were studied for estimating the soil organic carbon (SOC) storage in soils. The study revealed that SOC content in the surface 0.15 m and up to one m depth varied in different landforms. The content of mean organic carbon in the surface 0.15 m soils was highest in alluvial landform whereas basalt landform showed the highest in the upper one m depth. Granite-gneiss and sandstone landforms showed the least organic carbon storage in both the upper 0.15 m and up to one m soil depth. The mean SOC storage in the five landforms is in the order of basalt <62> alluvial <62> laterite <62> sandstone <62> granitegneiss. Parent materials were fount to influence the organic carbon storage through its control on soil texture. Drainage played a pivotal role in the distribution and amount of organic carbon especially in granite-gneiss and sandstone landforms. Grouping of soils on the basis of the different soil orders revealed that Vertisols have the highest organic carbon, whereas it was least in Entisols. The ranking of SOC storage in different soil orders was in the order: Vertisols <62> Inceptisols <62> Alfisols <62> Entisols.

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013001   Durg N L;Gajapathi Rao R;Sharma U P;Manjunath Y S (Atomic Minerals Directorate for Exploration and Research, , Nagarbhavi, Bangalore-560 072) : Potentiality of the kaladgi basin for uranium mineralisation. Indian Mineralogist 1999, 33(1), 19-26.

Discovery and establishment of structurally-controlled, carbonate- and granite-hosted uranium mineralisation in the more or less coeval Bhima and Cuddapah (Purana) basins necessitate a relook of the Kaladgi basin for such mineralisation. Fertile basement granites of the Kaladgi basin assaying on an average 20 ppm U₃O₅ with anomalous values ranging from 50 to 910 ppm of U₃O₈ and 16 to 170 ppm of ThO₂, at many places demonstrate the presence of notable content of uranium in the system. In the light of our recent radiometric surveys, favourable factors for possible uranium mineralisation in the basin are discussed.

013000   Bhalla M S;Satya Narayana B;Subrahmanyam K; Sudheer Kumar M S;Gangadhara Rao M;Lakshmi K J P (NO, National Geophysical Research Institute, Hyderabad-500 007) : Low field hysteresis and a palaeomagnetic stability criterion for rock samples from various localities of deccan traps of India. Indian Mineralogist 1999, 33(1), 31-6.

Metastable magnetic states often occur in basalts and cause spurious magnetisation in them. The detection of their presence by study of Rayleigh loops helps to isolate specimens containing little or no secondary overprint for palacomagnetic work, and increase the precision of determination of magnetic directions. This procedure has been applied to about 1810 specimens obtained from 480 oriented rock samples collected at 73 sites in five different Deccan Tarap regions at Aurangabad. Girnar and Pavagarh, Jalna and Dbar. The agreement between the mean Natural Remanent Magnetic (NRM) directions isolated by the above procedure; and those determined after alternating field demagnetisation has been found to be very good. This indicates that the rocks from these localities are highly stable and suitable for the determination of a precise palaeomagnetic direction without the need of progressive demagnetisation.

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012999   Basavaraajappa H T;Srikantappa C (Department of Geology, University of Mysore, Manasagangotri, Mysore-570 006) : Retrograde charnockite -gneiss relations in the kollegal shear zone, Karnataka, India. Indian Mineralogist 1999, 33(2), 70-80.

Within the Kollegal Shear Zone (KSZ) in the Dharwar craton, charnockitic to endrbitic granulites of the Biligirirangan Hills have been highly deformed with the formation of mylonites, ultramylonites and pesudotachylites. Granulites show various retrograde metamorphic reactions with the predominance of epidote-amphibolites facies gneisses in the shear zone. Low to high salinity aqueous fluids predominate (3 to 35 Wt. 5% NaCl equ.) in the shear zone rocks with low density CO₂ -rich (0.76-96 g/cc) inclusions in contrast to high density CO₂ inclusions in the BRG (1.00 to 1.09 g/cc). Retrogression of charnockite to gneisses is isochemical.

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012998   Bansal M;Vijan A R;Mahar Y S;Ghosh N;Prasad K S;Prabhu B N (Geochemistry Division, KDM Institute of Petroleum Exploration, Oil and Natural Gas Corporatio, Dehradun-248 195) : Rb-Sr dating of lower vindhyan sediments from Son valley, Madhya Pradesh, India. Indian Mineralogist 1999, 33(1), 1-9.

Reports Rb-Sr studies on Lower Vindhyan sediments (Semri Group) from an exploratory well, Jabera-A drilled in the Son valley part of Vindhyan Basin in Madhya-Pradesh, Central India. Samples from two conventional cores viz CC-3 (depth: 529.5 - 538.5 m) belonging to the Rohtas Formation and CC-28 (depth: 3391.4-3391.9 m) belonging to the Kajrahat Formation were analysed. Rb-Sr data on <60>2 mm illite rich clay fractions of CC-3 define an isochron corresponding to age of 939±22 Ma and an initial ⁸⁷Sr/⁸⁶Sr ratio of 0.765±170 (MSWD=0.20). CC-28, which is a highly compacted siltstone containing dominantly illite and gives an isochron age of 1014±18 Ma. with an initial ⁸⁷Sr/⁸⁶Sr of 0.73067±90 (MSWD=1.68). These ages are interpreted as the time of diagenesis after deposition and compaction of this sedimentary rock.

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011992   Srinivasa Gowd S;Sudheer A S (Department of Geology, S V University, Tirupati-517 502) : Major ion hydrogeochemistry of Vadamalpet Mandal, Chittoor district, Andhra Pradesh. Indian J Geochem 1999, 14, 47-57.

Major ion hydrogeochemistry of Vadamalapet Mandal is taken up for study and evaluation of its suitability for drinking and irrigation purposes. The study area comprising an area of 84 km² lies in between Latiudes 13°27' to 13°36' N and Longitude 79° 26' to 79°34' E, and mainly occupied by granite, which is intruded by delerite dykes and quartz veins, quartzite with shaly intercalations, and alluvium. The paper presents the results of chemical analyses of 39 groundwater samples which are covering the entire study area. The data has been tested for possible hazards due to total dissolved solids, sodium, bicarbonate, chloride, and sulphate. From the assessment, it is known that the majority of the water samples are good either for drinking or for agriculture in the study area.

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011991   Sinha A K;Chandra R;Srivastava R K (Department of Geology, Banaras Hindu University, Varanasi-221 005) : Spatial and temporal distribution of carbonatites, alkaline rocks, picrites and tholeiitic basalts in the deccan trap province and their interrelationships in a plume model. Indian J Geochem 1999, 14, 69-78.

Large igneous provinces (LIP), like the Deccan Trap province in India, include other rock types besides the CFBs. These include carbonatites, Na-rich alkaline rocks of ijolitic family, K-rich basalts and peralkaline intrusives types with giant psedoleucites, and picritic and tholeiitic basalt dykes constituting volumetrically with CFBs well over 99% collectively. Several complexes along lower Narmada rift valley and its westward extension into Saurashtra and Kutch as well as along extended Cambay rift have either carbonatite or phonolitic/phononephelinitic rocks mostly occur as plugs ± minor flows. Rocks other than CFBs (tholeiites) have been studied in isolation by several workers during the past three decades. This key paper is an overview of the entire magmatic activity which has been explained as a logically coherent sequence of events on a plume model and reactivisation of older fault zones.

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011990   Shahid S;Nath S K;Patra H (Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur-721 302) : Ground water assessment and management within typical laterites around Salboni district Midnapur (W.B.). J Indian Wat Wks Ass 2000, 32(2), 101-6.

011989   Sarmah R N (Department of Geology, Nagaland University, Kohima) : Textural differentiation of the Barail sediments exposed in and around Kohima, Nagaland. Bull pure appl Sci-Sect F 1998, 17(1-2), 11-15.

The grainsize curves of the Barail sediments exposed in and around Kohima show clear bimodality. When treated as a three component system and plotted in a ternary diagram, the grainsize distribution reveals two linear trends of textural evolution, one ranging from poorly sorted sand-silt-clay mixture to moderately well sorted end member and the other from a poorly sorted silt-clay mixture to the same end member.

011988   Saadon M N;Camerlengo A L (Faculty of Science and Technology, University College Terengganu Universiti Putra Malaysia, Mengabang Telipot-21030, Kuala Terengganu (Malaysia)) : On the behaviour of the salinity, the temperature, the density and the dissolved oxygen in the straits of Mallaca. Ultra Scient phys Sci 2000, 12(3), 348-54.

Variability of physical properties, especially temperature, salinity density and dissolved oxygen, is addressed. Three cruises have been conducted in the Malacca Strait (Nov. 23 to Dec. 1. 1998, Mar. 25 to Apr. 4, 1999, and Aug. 20 to 29, 1999) covering 24 sampling stations. Data of the physical parameters have been gathered using multiparameter hydrolab probe. Temperature salinity, density and dissolved oxygen profiles have been analyzed. All profiles show homogeneity of physical parameters in the water column in all the sampling periods, except for very deep stations in the northern region of the strait. However, variabily of physical parameters is observed between each sampling period (or cruise).