005475   Harris R A (US Geological Survey, , Mail Stop 977, 345 Middle Field Road, Menlo Park, CA 94025, USA) : Earthquake stress triggers, stress shadows, and seismic hazard. Curr Sci 2000, 79(9), 1215-25.

Many aspects of earthquake mechanics remain an enigma at the beginning of the twenty-first century. One potential bright spot is the realization that simple calculations of stress changes may explain some earthquake interactions, just as previous and ongoing studies of stress changes have begun to explain human-induced seismicity. This synthesis supplied some clues about certain aspects of earthquake mechanics. It also demonstrates that much work remains to be done before we have a complete story of how earthquakes work.

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005474   De U S;Ratnam K;Mukhopadhyay R K (NO, Meteorological Office, Pune-411 005) : Zonal wind variations in the stratosphere and mesosphere over the equatorial region of Asia and possible association with Indian summer monsoon rainfall. Mausam 1999, 50(3), 243-50.

Behaviour of stratospheric and mesospheric zonal winds in the equatorial region of Asia has been studied using rocket wind data from 921 flights for the period from 1970 to 1993 over Thumba (India) and upper wind data in the lower stratosphere over Singapore (S.E. Asia) from 1970 to 1997. It is inferred that the quasi-biennial oscillation (QBO) with periodicity of 22 to 30 months and annual cycle with periodicity of 11 to 12 months dominate in the lower stratosphere over Thumba, while the semi-annual cycle is predominent in the upper stratosphere and mesosphere. QBO in the lower stratosphere over Singapore has been observed to be significant with periodicity of 22 to 28 months, whereas the annual cycle has no significane. Correlation coefficients are statistically significant between the seasonal rainfall over India and zonal winds at 10 hPa (30 km) during winter months and also zonal winds at 30 hPa (24 km) during premonsoon months. However, there is an improvement in correlation if combined circulation of zonal winds at 10 hPa during winter and at 30 hPa during premonsoon is considered. Zonal winds at 50 hPa (20 km) and 30 hPa (24 km) over Singapore during monsoon months show diagnostic value with seasonal rainfall over India having significant concurrent correlation coefficients, however winds during winter and premonsoon do not show significant correlation with Indian monsoon. Thus, this could be used to monitor the progress of south-west monsoon performance but not in predicting it.

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005473   Bilham R;Gaur v K (CIRES and Department of Geological Science, University of Colorado, Boulder, Co 80309-0399, USA) : Geodetic contributions to the study of seismotectonics in India. Curr Sci 2000, 79(9), 1259-69.

Earthquakes in India are caused by the release of elastic strain energy created and replenished by the stresses resulting from India's collision with Asia. Accumulating strain distorts the surface of the Indian plate, which despite its slow development can now be detected using precision geodesy. The largest and most severe earthquakes occur on the boundaries of the Indian plate to the east, north and west of the subcontinent. Historically, these areas have been somewhat neglected by precise geodesy and it is only recently that suitably dense networks capable of spanning entire plate boundaries have been developed. Earthquakes within the subcontinent, though devastating, have also remained unserved by historical geodesy in India because the rupture areas of these events are small and have tended to occur between networks of adequate precision. Since 1990, the widespread availability of GPS geodesy has resulted in a number of significant findings related to the translation, deformation and rotation of the Indian plate and to deformation of its margins. The next decade is likely to see the uncertainties of these estimates fall by a factor of 4, permitting estimates of changes of rate in space and time. Discuss these new findings and their historical antecedents, and identify current trends in seismogeodetic research that are likely to contribute to a new understanding of future Indian earthquakes.

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005472   Bhattacharya S N;Dattatrayam R S (Indian Meterological Department, , Mausam Bhavan, Lodi Road, New Delhi-110 003) : Recent advances in seismic instrumentation and data interpretation in India. Curr Sci 2000, 79(9), 1347-58.

There are 212 seismological observatories being operated in Indian by various R&D institutions, river valley authorities and universities. The Department of Earthquake Engineering (DEQ), University of Roorkee is operating and Indian National Strong Motion Instrumentation Network (INSMIN) and few strong motion arrays in the Himalayan region and north-east India. IMD is engaged in the manufacture of analogue seismographs since 1960s. Portable analogue recorders are being manufactured at the Central Scientific Instruments Organization (CSIO), Chandigarh, where design of digital recorders is also in progress. The digital data processing and analysis in time and frequency domains, has greatly improved the hypocentral location capability and ability to evaluate detailed source parameters.

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005471   Arya A S (Department of Earthquake Engineering, University of Roorkee, Roorkee-247 667) : Recent developments toward earthquake risk reduction in India. Curr Sci 2000, 79(9), 1270-7.

Developing country like India, with a variety of building practices and social and economic structure, needs to evolve its own strategies for seismic hazard evaluation. Occurrence of few damaging earthquakes during the last decade has pointed to our shortcoming in risk reduction programmes. A meaningful programme must incorporate appropriate building codes and also create public awareness. Several initiatives are now being taken at research and management levels. An update to these initiatives and steps to strengthen disaster mitigation programmes are discussed.

005470   Anderson J G;Brune J N;Anooshehpoor R; Shean-Der Ni (Seismological Laboratory, University of Nevada, MS 174, Reno, Nevada 89557, USA) : New ground motion data and concepts in seismic hazard analysis. Curr Sci 2000, 79(9), 1278-90.

Strong motion data from the Izmit, Turkey and Chi-Chi, Taiwan earthquakes have pointed out uncertainties in current strong motion attenuation curves for large earthquakes. Although the near-source strong motion data from these two-recorded large earthquakes were well below the estimated values by the ground motion models, they were consistent with constraints estimated from precarious rock methodology. This discrepancy could be a result of inadequate ground motion data for large earthquakes and possible flaws with a number of statistical parameter assumptions that were necessary for extrapolation from existing database, which is dominated by small earthquake data. Discusses several important issues that have the potential to cause major impact on seismic hazard analysis. They are : partitioning of uncertainties into aleatory and epistemic contributions, quantification of precarious rock observations and use of the data to constrain and improve ground motion models, continuing to deploy strong motion instruments near major faults since only more strong motion data will definitively resolve the issues of what is normal behaviour, and understanding through modelling and observation, the physical phenomena that affect strong motion, including the effect of total fault offset, surface rupture and type of faulting.

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005469   Ambraseys N (Department of Civil Engineering, Imperial College of Science, Technology and Medicine, London SW7 2BU, UK) : Reappraisal of north-Indian earthquakes at the turn of the 20th century. Curr Sci 2000, 79(9), 1237-50.

Reviews the seismicity of northern India during the little-known period from 1892 to 1915 and summarizes evidence for 50 events, few of which are listed in parametric catalogues. Using instrumental data and established procedures, surface-wave magnitudes are calculated uniformly and epicentral locations are reappraised.

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004460   Visweswara Rao C;Rajendra Prasad E (Department of Geophysics, Andhra University, Visakhapatnam-530 003) : Interactive computer package for modelling the crustal structure from Bouguer anomalies : methodology and application. J Geophys 2000, 21(1), 31-6.

Interactive computer package for interpreting Bouguer gravity anomaly in terms of crustal structure has been developed. Power spectral analysis, regression analysis, the digital filter for separating lower and higher wavelength components and the properties of sin x/x function are used to formulate the methodology for crustal modelling. Two Bouguer animaly profiles, viz., Koyna I (Guhagar - Chorochi) and Koyna II (Kelsi Loni) are re-interpreted using the developed package and the results are in general agreement with those of the earlier analyses of these profiles establishing the utility of the package.

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004459   Srinivas S;Murthy A S K;Yadav G S;Srivastava K M (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Crustal structure of Chattisgarh region, Madhya Pradesh, India. J Geophys 2000, 21(1), 41-5.

Regional gravity anomaly profile across the Chattisgarh region is studied in terms of basin configuration and crustal structure. Two gravity models are inferred viz., a two layered crustal model and a differential crustal model, out of which the differential crustal model appears to be realistic. Both the models indicate a maximum thickness of 3.5 km for the sediments and an up-warp of 2 km in the moho under the Chattisgarh basin.

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004458   Sinha D K;Fahmi S;Bhatt A K;Singh G;Singh R (NO, , C-31, Devnagar, Tonk Road, Jaipur-302 018) : Evidences for soda metasomatism in Ladera-Sakhun area, northeastern Rajasthan. J Geol Soc India 2000, 56(5), 573-82.

Albitite and albitised banded gneissic country rock from the Ladera-Sakhun area, situated about 80 km southwest of Jaipur, show several evidences for soda metasomatism. Megascopic evidences include reddening of outcrops due to aventurisation, gradational contacts between albitite and gneisses, development of metasomatic minerals, dequartzification, epidotization and cataclasitisation. Microscopic evidences include relict microcline in the newly formed albite grain, poor and discontinuous development of twin lamellae in albite giving step-like appearance, ubiquitous sweeping extinction in albite due to cataclasitisation, occasional mortar texture in albitite, tapering of twin lamellae within the grain, two lamellae forming in chequered fashion, development of aventurine albite containing dusty Fe-oxide inclusions, development of albite along twin/cleavage plane of microcline, formation of new albite in plagioclase, destruction of sericite in plagioclase of albitised granite, formation of myrmekite of intergranular, intragranular and rim types, development of epidote corona around clinopyroxene in pyroxenite, partial to complete dequartzification and filling up of voids by calcite. Petrochemical evidences of increased characteristic values of Na2O from 3.17 to 7.00 wt%, K2O and SiO2 from -0.03 to -6.00 wt% and -0.76 to -10.55 wt% in the unalbitised to albitised rocks respectively.

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004457   Sharma A K;Walia V;Virk H S (Department of Physics, Guru Nanak Dev University, Amritsar-143 005) : Effect of meteorological parameters on radon emanation at Palampur (H.P.). J Geophys 2000, 21(1), 47-50.

Effect of meteorological parameters on radon emanation in the soil-gas at Palampur station has been studied for time window March 1993 to March 1995 and the results obtained are correlated in terms of radon fluctuations. The radon value is found to be positively correlated with temperature, relative humidity and mild rainfall whereas it shows inverse relationship with evaporation, wind velocity and heavy rainfall. The overall correlation is found to be week resulting in a cumulative effect of 10-20 % on radon emanation at the most. Other parameters, e.g., sunshine hours and vapour pressure cause negligible effect on radon emanation rate.

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004456   Shahid S;Nath S K;Patra H P (Department of Geology & Geophysics, Indian Institute of Technology, Kharagpur-721 302) : Integrated approach for ground water investigation around Nazarganj near Kasai river bed, Midnapur dist., West Bengal. J appl Hydrol 0000, 12(4), 15-21.

Combined geological, geophysical and hydrogeological investigation around Nazarganj (lat. 22°23'30''N, long. 87°19'E) near Kasai river, Midnapur dist., West Bengal is used to study the ground water potential of the area. Geological and geomorphological studies from satellite imagery, reveal the existence of river terraces. Geoelectric sounding results verfied from borehole data indicate the presence of a shallow unconfined aquifer. A thick deposit of sand bed, as predicted from geomorphological and geophysical studies, is also confirmed from borehole data. Pumping test data show an average yield of about 35,000 liters/hour at an approximate drawndown of 0.18 meter for a continuous pumping of 24 hours. The grain size analysis shows that the porosity of aquifer varies between 30% and 40%. The potability of water in the area is established through chemical analysis of water sample collected from the pumping well.

004455   Sarbajna C;Krishnamurthy P;Paul A K;Banerjee D C (NO, Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad-500 016) : Mineralogical and chemical characteristics of complexly-zoned columbite-tantalite from the rare metal pegmatites of southern Karnataka. J Geol Soc India 2000, 56(5), 557-71.

Detailed mineralogical and chemical studies by EPMA on the Nb-Ta minerals from the rare metal pegmatites of sourthern Karnataka have revealed wide compositional variations, and the presence of some new minerals like tapiolite and microlite, hitherto unreported from these pegmatites. Back scattered electron (BSE) images have indicated complex zoning patterns such as oscillatory, patchy and/or their combinations, associated with replacement of columbite-tantalite by microlite, manifested by the variations of Nb2O5, Ta2O5, FeO and MnO. Such features, although known from a few rare metal pegmatites of the world, are being recorded here for the first time in India. The zoning of the columbite-tantalites has been attributed to periodic changes in the composition of the major components such as Nb, Ta, Fe and Mn in the pegmatite fluid system, apparently influenced by the late stage fractionation of volatiles. This ultimately generated fluids rich in a Ta and Na, resulting in resorption and replacement with patchy zoning of early formed, zoned columbite-tantalites.

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004454   Ravi Shankar;Gopal Singh;Gopendra Kumar; Maithy P K (Geological Survey of India, , Lucknow) : Pre-Gondwana events and the evolution of Indian sub-continent as a part of Gondwana land. Geosci J 1999, 20(2), 165-80.

During pre-Gondwana time-frame, eight distinct tectonothermal events are identified; each event is related to an orogenic episode accompanied by a change in biotic assemblage. Amongst these, the terminal Paleoproterozoic event (ca 1.6 Ga) is of utmost significance in unravelling the ancestry of Gondwana assembly. The Indian sub-continent is a mosaic of four distinct Archaean-Early Paleoproterozoic terranes/blocks, viz., Bundelkhand (BB), Dharwar (DB), Trans Aravalli (TAB) and South Indian Sri Lankan Granulite (SISLGB) blocks. The first three welded together along well defined mobile belts, viz. the Satpura (SMB) and Aravalli-Delhi (ADMB) mobile belts, during 1.6 Ga event. During this event, the East Antarctica also sutured to DB along Eastern Ghat Mobile Belt, on the one hand, and to the West Australian Craton along Albany-Fraser Mobile belt, on the other. The BB extended northwards underneath the Himalaya, possibly upto Tein Shan Suture and eastwards upto Darling Mobile belt that sutured it with West Australia. The TAB extended westwards to include Arabian-Nubian Shield or Central Arabian Craton. These accreted blocks formed part of the East Gondwana land. These were subjected to differential peneplanation and formed the basement as well as provenance for the deposition of four platformal supersequences of varying spatial or temporal distribution and distinct assemblages. Each super-sequence is separated from the other by hiatuses related to tectonothermal events at ca 1100±100, 750-700 and 500 Ma.

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004453   Raval U;Veeraswamy K (NO, National Geophysical Research Institute, Hyderabad-500 007) : Radial and linear modes of interaction between mantle plume and continental lithosphere : a case study from western India. J Geol Soc India 2000, 56(5), 525-36.

Study examines the interaction between continental lithosphere (CL) and deep mantle plume. For this purpose, the Indian CL and the Reunion plume have been considered, with special emphasis on the consequent development of geophysical, tectonic and structural features. It reveals a bimodal pattern (linear and radial) of these manifestations. The radial one is correlated with the outburst of the plume-head, while the pre- and post-outburst phases follow a linear mode due to the traverse of Indian plate over the plume. It is seen that, the plume-CL interaction is facilitated by mobile belt and resisted by cratons.

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004452   Ramkumar M;Sudha Rani P;Gandhi M S;Pattabhi Ramayya M;Rajani Kumari V;Bhagavan K V S;Swamy A S R (NO, Delta Studies Institute, Andhra University, Visakhapatnam-530 003) : Textural characteristics and depositional sedimentary environments of the modern Godavari delta. J Geol Soc India 2000, 56(5), 471-87.

Textural data of the sediments of Godavari delta indicate the control of energy over grain size and other statistical parameters. These parameters also explain the regional energy conditions, which are indicative of many sub-environments. The prime environmental factors viz. transportation, deposition and preservation vary in time and space, which in turn, produce variability as well as shared nature of grain size characteristics. Many sub-environments have similar depositional/energy regimes making their distinction a difficult task. It is also established that only group of environments could be delineated, rather than individual environments, based on manual observations and discriminant plots of textural data.

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004451   Pandey P C;Gairola R M (Antarctic Study Centre, , Vasco-da-Gama, Goa-403 804) : Satellite oceanography : review of the progress and future prospects. Proc Indian Natn Sci Acad-Pt A 2000, 66(3-4), 317-65.

Satellite oceanography has opened up a whole new dimension in our ability to observe the vast oceanic region in addition to providing information about other components of the climate systems. The developments in the sensor technology using various regions of the electromagnetic spectrum, coupled with the developments in computers and ocean modelling, have enabled the scientists to visualise the 3-D structure of the ocean and their evolution. Many of the parameters of the physical and biological oceanography can now be obtained from space with useful accuracies for several applications such as air-sea interaction and data assimilative predictive models. The current and planned satellites from various agencies offer new opportunities for scientific community and are playing a key role in global experiments such as World Ocean Circulation Experiment (WOCE) and Climate Variability (CLIVAR). The scatterometry, altimetry and radiometry have already provided critical information needed for El-Nino southern oscillation phenomena studies under Tropical Ocean and Global Atmosphere (TOGA) experiment. It has now become possible to study fronts and circulation of the Antarctic Circumpolar Current (ACC) in the southern hemisphere using altimetry data, which has remained a largely unexplored region due to hostile environment. Together with other newly emerging in situ data, scientists are able to learn more about the oceans and would be able to better manage the resources of the oceans in a sustainable manner. An attempt has been made to review the progress in remote sensing of the oceans, their limitations and potential applications.

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004450   Njau E C (Physics Department, University of Dar es Salaam, P O Box 35063, Dar es Salaam, Tanzania) : Sun-weather/climate relationships. I. Proc Indian Natn Sci Acad-Pt A 2000, 66(3-4), 415-41.

Some previous review papers on Sun-Weather/Climate Relationships (SWRs) acknowledge existence of observations which reasonable show links between tropospheric weather/climate and solar activity. However, no previous review paper on SWRs has reported any mechanism or theory which adequately explains the observed SWRs. In this review paper, authors extend and develop from what previous review papers have reported by updating the new enormous wealth of statistical evidence which proves beyond any reasonable doubt that SWRs actually exist. But unlike any previous SWRs review paper, this review paper reports also on statistical and data-based research results, mostly reported in the 1990s, which have laid the foundation for establishment of a new physical mechanism as well as the associated theory which appear to satisfactorily explain the observed SWRs. Details of this physical mechanism and associated theory are, however, presented in Part II of this series. Another unique feature of this review is its inclusion and illustration of a recently developed research approach which involves analysis of variation envelopes of climate/weather parameters using standard signal processing theory. Finally recent statistical and records-based research results are presented showing that the recent global temperature rise may, to a reasonable extent, be attributed to solar forcing.

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004449   Maulik P K;Chakraborty C;Ghosh P;Rudra D (Geological Studies Unit, Indian Statistical Institute, 203, B T Road, Calcutta-700 035) : Meso- and macro-scale architecture of a triassic fluvial succession: Denwa formation, Satpura Gondwana basin, Madhya Pradesh. J Geol Soc India 2000, 56(5), 489-504.

The lower part of the Denwa formation is characterized by an alternation of medium to fine grained, thick, sheet-like, sandstone bodies and red mustone intervals having centimetre to decimetre scale fine grained sandstone interlayers. The thick sandstone bodies are comprised of several groups of storeys, and individual storeys are made up of macroform strata reflecting frontal, oblique and vertical accretion. It is evident from the overall architecture that the lower part of the Denwa Formation represents an alluvial plain characterised by sandy, braided channel belts and associated floodplain/basin. The upper part of the Denwa Formation is characterised by conspicuous absence of thick multistorey sandstone bodies. It is predominantly a mudstone dominated, sand-poor succession characterized by ribbon-shaped bodies encased within pedoturbated mudstones. Ribbon-shaped bodies internally show inclined heterolithic (sand-mud) stratification representing lateral accretion of channel bars of high sinuosity rivers. The upper part of the Denwa Formation is interpreted to represent deposits of a network of meander channels laterally separated by well-developed and stable inferfluve and floodplain areas. The changes in the fluvial styles represented in the Denwa succession have been attributed to changes in the aggradation rate, avulsion frequency and climatic setting.

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004448   Laskar S K (Department of Mathematical Sciences, Tezpur University, Tezpur-784 001) : Note on uniqueness of depth determination from observed potential field data. J Geophys 2000, 21(1), 37-40.

Attempt is made to discuss uniqueness of depth determination from observed potential field data on reproducing the field by simple layer density σ belonging to a horizontal half-space boundary S that lies below the datum level S^-. Assuming that the σ belonging to S reproduces the field over S^- as S gradually moves downward and crosses the causative mass m, it is theoretically shown that the σ exhibits a smooth continuous behavior when S is shallower than m and an erratic behavior when S is partially or wholly below it. The depth to the shallowest S with an erratic σ defines the depth to the top of the causative mass and this depth is unique.

004447   Khullar N K;Soni A;Jaspal Singh;Jaggi A K (Department of Civil Engineering, Punjab Agricultural University, Ludhiana-141 004) : Selection of rainfall frequency distribution model for Punjab. J appl Hydrol 1999, 12(4), 22-8.

Goodness of fit of three frequency distribution models, viz. Lognormal 3-parameter, Lognormal 2-parameter and Extreme value type 1 distribution has been tested for maximum 1-day, maximum 2-day and maximum 3-day duration of rainfall data of Punjab by using Kolmorgov - Smirnov test method. Two methods viz. method of moments and method of maximum likelihood have been used for estimation of parameters of these distributions. The analysis shows that Lognormal - 3 parameter distribution model using maximum likelihood method of parameter estimation is the best fit distribution model for all three duration of rainfall.

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004446   Kesavamani M;Ramachandran C;Prasad R M C (Geophysics Division, Geological Survey of India, Bandlaguda, Hyderabad-500 068) : Concentric and radial upwarps and downwarps: crustal architecture of the Indian shield from gravity maps. J Geophys 2000, 21(1), 3-18.

Regional and residual gravity field components of the Bouguer gravity anomaly over the Indian Shield are analysed to understand its crustal structure and tectonics. The gravity lows in the regional gravity field indicate the cratons and/or zones of subsidence, while the highs correlate with the surrounding mobile belts and/or deep gravity basement ridges. The Moho relief map shows thicker crust over the cratonic areas and a thin crust over the mobile belts possibility due to inhomogenous upper mantle. The residual gravity high and low anomalies reveal a heterogeneous basement of mafic and felsic rocks, which respectively indicate the synformal and domal structures. The arcuate central Indian gravity high (CIH) in the regional field, possibly defining the Narmda-Son-Brahmaputra lineament, divides the Indian shield into two major blocks. The CIH together with the regional gravity high along Godavari valley forms a `Y' junction near Nagpur and indicates a radial deep basement ridge. The radial gravity high zone is associated with lows flanked by highs in the residual gravity field indicating a three-armed rift system. The steep gradients, possibly due to the transitional crust with associated thrust zones and en-echelon geometry, along the peripheries of the subcontinent and the disposition of the CIH suggest strike slip (dextral?) movements.

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004445   Indira N K;Yajnik K S (NO, C-MMACS, NAL Belur Campus, Bangalore-560 037) : Statistical analysis and visualisation of gold mine data : a case study of Kolar gold mine. J Geophys 2000, 21(1), 25-9.

Case study based on the statistical analysis of the Footwall Lode of the Champion Reef Mine of the Kolar Gold Mines has been made. It has been found that the gold deposition in terms of the grade values follows a univariate lognormal distribution as does the accumulation. On the basis of the distribution of the width of the lode, the analysis is extended further to support the possible existence of two different lodes using the F-test, two sample t-test and Kolmogorov-Smirnov two samples test. The data is geometrically modelled on a graphic workstation.

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004444   Hota R N (Department of Geology, Ravenshaw College, Cuttack-753 003) : Quantitative stratigraphic correlation - a case study from two borehole sections of Barakar formation, Talchir coalfield, Orissa. J Geol Soc India 2000, 56(5), 517-24.

Quantitative stratigraphic correlation of lithounits and microfacies of Barakar succession in two widely separated borehole sections from Talchir coalfield, Orissa display strikingly different results. When major lithounits are considered, one-to-one correspondence between the two sections becomes significant and indicates the continuity of single homogenous succession deposited under an identical depositional environment. Lack of significant correlation of microfacies, on the other hand, suggests existence of different subenvironments at different places during each phase of sedimentation. Thus a coal seam is likely to be restricted in its lateral continuity and show differences in the nature of floor and roof rocks, which are vital for safe and economic mining.

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004443   Gopendra Kumar (NO, , 48, Pandariba, Old Kanpur Road, Lucknow-226 004) : Tectonics of the Himalaya. Geosci J 1999, 20(2), 181-98.

In the Himalaya, the rocks ranging in age from Late Archaean to Holocene, are grouped into 15 Supersequences; each separated from the other by an unconformity of varying magnitude. The data on structure from different supersequences, their mutual relationships and the presence of acid magmatic rocks indicate involvement of rocks in several phases of the pre-Himalayan and Himalayan orogenic, and post-Himalayan epeiorgenic movements. The imprints of almost all major global orogenic events are identifiable in the Himalaya. Discusses the significance of each orogenic movement in the tectonic evolution of the Himalaya.

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004442   Dutt A B;Mukhopadhyay A (NO, , P481 Keyatola Road, Calcutta-700 029) : Ancient denudational surfaces in the Gondwana sequences of Peninsular India. J Geol Soc India 2000, 56(5), 505-16.

Gondwana basins of Peninsular India contain a thick pile of clastic sediments of predominantly fluvial origin. As expected in such a depositional milieu, the sedimentary pile is punctuated by numerous episodes of contemporaneous uplift, non-deposition and erosion. Most of these events are localised in nature and hence not correlatable from one basin to another. However, a few events of regional nature can be recognized. These include Lower Barakar (Early Permian) of Hutar basin of Koel valley, Barren Measures (Late Permian) and Triassic/Jurassic contact of Rewa and Satpura basins, and Late Cretaceous Lameta Beds in Rewa Basin. Breaks represented by conglomerate beds occur in Early Permian Barakar strata of Talchir coalfield and Late Mesozoic Bagra Formation of Satpura basin. The palaeosols vary in thickness from 4m to 25m and are characterised by red brown clay with mottles, rootlets, slickensides, ferruginous concretions and calcareous veinlets. The palaeosols are hydromorphic and are developed under poorly drained to well drained groundwater conditions. Even where the palaeosols are not present, the bedrock displays evidences of deep weathering. These probably represent the earlier topographic positive areas affected by physical weathering and intense groundwater activity.

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004441   Dole G;Peshwa V V;Kale V S (Department of Geology, University of Pune, Pune-411 007) : Evidence of palaeoseismic event from the Deccan plateau uplands. J Geol Soc India 2000, 56(5), 547-55.

Palaeoseismic evidence is recorded for the first time from the upland region near the crest of the Deccan plateau. Some of the soft-sediment deformation structures from Quaternary sediments in the Chandanapuri valley are interpreted as seismites. These sediments rest nonconformably upon the Deccan Traps and are inherently anomalous vis-a-vis their location in the river valley. Based on various features and their position in the succession of the sediments, these seismites are provisionally attributed to a single event with an inferred magniture <62>6.5 M, which occurred 5000 - 7000 years ago. This report highlights the need to re-evaluate the traditional perception of the aseismic nature of the main Deccan plateau.

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004440   Cowan D R;Bullock S;Cowan S;Tompkins A; Dentith M (NO, Cowan Geodata Services, 12 Edna Road, Dalkeith, W A 6009, Australia) : Image display and tone and texture in aeromagnetic data. J Geophys 2000, 21(1), 19-24.

Qualitative aeromagnetic interpretation using high-resolution filtered images is essentially a pattern recognition technique involving identification of magnetic elements from changes in magnetic relief and magnetic texture. Magnetic relief consists of anomaly amplitude and shape and is relatively objective. Magnetic texture consists of shape, size and continuity of adjacent anomalies and is more subjective. Amplitude in image processing equates to tone, the relative brightness of individual from tone, which is defined at one location (pixel) while texture occurs over some finite area and hence requires some finite number of pixels to represent it. Texture can occur at several scales and larger scale aggregates are sometimes described as structure to distinguish them from smaller scale texture variations. The spatial arrangement of contrasting tones and textures within an image are referred to as patterns. An experienced interpreter can recognise type patterns characteristic of the magnetic expression of geological features. It was concluded that the different filters have different amplitude and wavelength responses and the results are complementary. The GLCM texture filter probably provided the best enhancement of subtle low amplitude anomalies but had little tonal information content limiting the effectiveness of the filter in the magnetically active areas.

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004439   Bisht B S;Israili I H;Khare M K (NO, Atomic Minerals Directorate for Exploration and Research, Hyderabad-500 016) : Distribution of U-Th-K in metamorphic rocks of Siang group in parts of Baririjo-Maro-Gamkak-Kau-Darak section, west Siang and upper Subansiri districts, Arunachal Pradesh. J Geol Soc India 2000, 56(5), 537-45.

Metamorphic rocks of the Siang Group in West Siang and Upper Subansiri districts, Arunachal Pradesh, have anomalous concentration of intrinsic radioelements (viz., U, Th and K). The study reveals that psammopelites comprising paragneiss, carbonaceous phyllite and quartzite/phyllite/mica schist (av. 8.2-27.3 ppm U, 19.7-42.8 ppm Th, 2.2-4.0% K); volcano-sedimentary garnet amphibolite (av. 14.3 ppm U, 23.1 ppm, 1.8% K), and intrusive feldspar porphyry (av. 12.7 ppm U, 26.3 ppm Th, 5.9% K) have higher radioelement contents, particularly U, in comparison to pelitic graphite schist, iron formation and metabasics (av. <60>4.2-4.7 ppm U, 18.5-60.2 ppm Th, 3.3-4.9 %K). All rock types, except feldspar porphyry, exhibit noticeable difference in mean U and Ea (eU) values. Variation in U content has been conspicuous in carbonaceous rocks, with phyllitic unit more enriched than graphitic schists. U and Th contents appear to be independent of K concentration in all rock types. Such features of variable radioelement concentration indicate differences in the composition of precursor sedimentary rocks and also differential mobility during metamorphism.

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004438   Bijai Prasad (NO, KDM Institute of Petroleum Exploration, Oil and Natural Gas Corporatio, Dehra Dun-248 195) : Palynological characterisation, biostratigraphy and depositional environment of pre-tertiary lithounits of Krishna-Godavari basin, India. Geosci J 1999, 20(2), 143-64.

Distinctive palynological assemblages and age marker palynomorph species are documented from the holo- and hypostratotypes of newly proposed and already known Pre-Cretaceous (Gondwana) and Cretaceous lithounits of the Krishna-Godavari Basin to determine their precise age and environment of deposition. A biochronostratigraphic framework is presented for these lithostratigraphic units. Draksharama Argillite, Kommugudem and Chintalapudi formations characterise the Lower Gondwana (Permian) palynofloras, and the recovered assemblages indicate lower Early Permian (Asselian-Scythian-Anisian to Carnian-Norian) palynofloras of Middle Gondwana which correlate with the Maleri palynofloras of Central India. Palynological associations of different lithounits suggest that Permian and Triassic rocks of Krishna-Godavari Basin are mainly fluvial and were deposited in Gondwanic rift graben. However, a marine incursion took place during the deposition of Draksharama Argillite in Early Permian which corresponds to the Manendragarh-Umaria marine intercalations of Central India. This basin seems to be a part of positive areas during major part of the Jurassic period and after that a rather continuous sediments from latest Jurassic to Late Cretaceous were deposited in the syn-and post rift phase of the basin in marine environment with minor fluctuations in bathymetry.

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004437   Bhattacharya K (NO, NCMRWF, Mausam Bhavan Complex, Lodhi Road, New Delhi-110 003) : Forecast surface temperature correction by estimation theory. Indian J pure appl Math 2000, 31(8), 921-32.

Surface temperatures are difficult to forecast using a General Circulation Model because of various imperfections in the latter. A new post-processing method has been reported, whereby 3rd day forecasts for surface temperature in Delhi (at 1.36m) are updated using sequential estimation theory. The method, with a Kalman filter, is recursive because only the latest correction (which contains the influence of past corrections in a weighted manner) is used to obtain future corrections. The difference between 3-hourly synoptic data for December 1995 from Safdarjang, New Delhi and the corresponding short term forecasts are inserted as input to "observations" for the Kalman filter scheme. The results are displayed for three different periods: for the beginning, middle and end of the month. Daily maximum and minimum temperatues before and after correction are also shown, along with observed values. The scope for extension of the work is discussed.

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004436   Ahmad S;Nagi D C (School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067) : Hydrogeomorphological mapping for groundwater prospecting using IRS-IA, LISS2 images: a case study of eastern Orissa an area between the Baitrani and Subarnrekha river. J appl Hydrol 1999, 12(4), 35-8.

Eastern part Orissa face acute potable water shortage and this area is one of the highly drought prone area of the India. The groundwater resources in the basin have not been adequately exploited. Investigation was undertaken to evaluate the groundwater promised zones. IRS-IA, LISS2 and false color composite of band 2,3,4 were interpreted visually to differentiate different geomorphological unit and to delineate the major trend of the lineament. The distinct geomorphic feature distinguish linear ridge, residual hill, vegetational anomaly, paleochannel, structural lineament. The study shows that paleochannel, intersection of structure lineament and residual hill are assuring zones for groundwater prospecting.

003406   Tripathy J K (Department of Marine Sciences, Berhampur Universty, Berhampur-760007) : Groundwater hydrochemistry around the salt pans north of Bahuda river estuary, Orissa. J envir Pollut 1999, 6(2-3), 197-202.

Groundwater samples around the salt pans, adjoining Bahuda river estuary (Andhra Pradesh-Orissa border) were analysed to determine the TDS (Total Dissolved Solids) as well as the concentration of major ions such as Na⁺, K⁺, Ca⁺⁺, Mg⁺⁺, HCO3^-, SO₄^-2, and Cl^- Analysis results indicated that the groundwater has been contaminated by salt water as evident from the value of ratios such as Cl^- /HCO₃^- and Mg⁺⁺/Ca⁺⁺. The concentration of several parameters such as TDS, Na⁺, and Cl^- in the groundwater nearby the saltpans exceeded the maximum permissible limits thereby making the water unfit for human consumption. The aquifers situated away from the saltpans are found to be less affected by salinity.

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003405   Surya Prakasa Rao G;Tewari H C;Rao V K (National Geophysical Research Institute, , Hyderabad-500 007) : Velocity structure in parts of the Gondwana Godavari graben. J Geol Soc India 2000, 56(4), 373-84.

Godavari graben, a palaeorift on the east coast of India, has been studied to delineate sedimentary thickness and basement configuration. First arrival seismic refraction data in the Chintalapudi sub-basin of Godavari graben have utilized for 2-D ray trace modeling. Results indicate a three layer velocity model, with velocities of 2.3-2.4, 3.2, and 4.0 km^-1 for the Gondwana (Permian to Cretaceous) sediments. Maximum depth to the basement, of velocity 5.5-5.7 kms^-1, is to about 3 km in the deepest part of the sub-basin. The basement is possibly the Eastern Ghats suite of rocks. These results are in conformity with the thickness of stratigraphic sequences in a deep bore well in the basin. Another layer of velocity 5.8-6.1 kms^-1 is present at about 4 km depth through out the study region, representing the base of Eastern Ghats Suite of rocks.

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003404   Srinivasa Gowd S;Kotaiah B (Department of Geology, Sri Venkateswara University, Tirupati-517 502) : Seasonal variation of water quality in a tropical Kalyani re-servoir, near Tirupati. Indian J envir Prot 2000, 20(6), 452-5.

Deals with the seasonal variation of physical, chemical and biological quality of water in a tropical Kalyani reservoir near Tirupati. The result indicate that there is a wide seasonal in the quality of water. Colour, pH, total solids, alkalinity, dissolved oxygen, BOD and COD, bicarbonates, and chlorophyll `a' concentrations fluctuate significantly in different seasons. These fluctuations are attributed by the influx of various organic and inorganic chemical constituents into the reservoir through run -off from the catchment area. This has also resulted propound impact on the chemical cost of water treatment in different seasons of the year.

003403   Sarkar I;Saraf A K (Department of Earth Science, University of Roorkee, Roorkee-247 667) : Some observations of the Chamoli earthquake-induced damage using ground and satellite data. Curr Sci 2000, 78(1), 91-7.

Havoc caused by the Chamoli earthquake of 29 March 1999 in the Alaknanda-Mandakini river valley region of Garhwal Himalaya was surveyed extensively and systematically, both in the field and from satellite data. The aim was to identify plausible patterns in the damage, so that observational constraints, useful for enhanced understanding of the earthquake and its related processes, could be established. This study provides evidences and constraints for reliable identification of:the meisoseismal zone of the earthquake, the possible up-dip and down-dip sections of the causative fault, the hypocentral zone, the fault plane and faulting mechanism, and the possible geological causes responsible for induced landslides to occur mainly on the southern slopes of the mountains.

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003402   Saran S;Sharma S;Roy P S (Indian Institute of Remote Sensing, , 4, Kalidas Road, Dehradun-248 001) : Extraction and refinement of landuse/landcover information from satellite digital data using fast Fourier transformation in spatial frequency domain. Curr Sci 2000, 78(1), 87-90.

Applicability of fast Fourier transformation (FFT), which deals with a co-ordinate space known as spatial frequency domain, has an advantage in the process of feature extraction for different landuse/landcover classes over the single supervised classification. The study deals with the extraction of low frequency component from the power or amplitude spectrum by applying inverse Fourier transform to convert back into spatial domain in the form of image. The derived Fourier transformed and filtered image is partially devoid of radiometric error which generally prevails in the remotely sensed data due to the atmospheric effect. This can be further minimized, whereby enhancing the texture of the image. The classified map extracted from the FFT image provides a better estimation of the landcover classes than the supervised classification alone. This method has applicability for mapping of natural resources and monitoring them.

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003401   Rathore S S;Singh M P;Prabhu B N;Misra K N (Geochemistry Division, KDM Institute of Petroleum Exploration, Oil and Natural Gas Corporatio, Dehra Dun-248 195) : Rb-Sr and K-Ar isotopic evidence for neoproterozoic (Pan-African) granulite metamorphism from the basement of Mumbai offshore basin, India. J Geol Soc India 2000, 56(4), 365-72.

Precambrian basement from well HBM-1 in the Heera oil field of Mumbai offshore basin has been dated by Rb-Sr and K-Ar methods. Five granulitic basement samples from three conventional drill cores have yielded Rb-Sr isochron age of 502 +25 Ma with an initial Sr ratio of 0.70855±0.00013. This age has been interpreted as the time of granulite facies metamorphism of the basement rocks in the region. Two whole rock samples from the basement of this well hae yielded mutually concordant K-Ar ages of 505±16 Ma and a507±17 Ma. The K-Ar ages are significantly similar o Rb-Sr age obtained from this well, suggesting complete isotopic reequilibration around 500 Ma ago. The time of secondary thermal heating around 500 Ma ago in the basement of Heera field coincides with the widespread Neoproterozoic (Pan-African) thermo-tectonic event extending from the Arabian Peninsula and eastern Africa covering Madagascar, southern India, Sri Lanka and East ANtarctica. Widens the limit of the pan-African zone, which hitherto was thought to be confined to the western part (presently southern part) of the Indian subcontinent, towards further east.

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003400   Rao J S;Hegde G N;Bhaumik B K (AMD Complex, Khasmahal Region, Jamshedpur-831 002) : R-mode factor analysis for finding geochemical association of radioactive and trace elements in the QPC of Dhanjori basin, Singhbhum, Bihar. J Geol Soc India 2000, 56(4), 385-93.

Factor analysis of multi-element data for Dhanjori conglomerates of Singhbhum district, Bihar, in eastern India reveals three fators accounting for about 57% of the total information contained in the data. Factors 1 and 2 are associated with radioactive elements. They also indicate that the provenance is a mixed felsic and mafic terrain, and that the minor and accessory constituents of these rocks are concentrated in the conglomerates. These two factors appear to result from the same sedimentological process. The Factor-3 results from the V-AI diadochy. Factor-1 which is seen to be associated with both zircon and radioelements does not contain Pb. Pb is relegated to the Factor-2.

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003399   Rao A T;Divakara Rao V;YOshida M;Arima M (Department of Geology, Andhra University, Visakhapatnam-530 003) : Oxygen isotope values in granulite facies rocks from the eastern ghats granulite belt, India. J Geol Soc India 2000, 56(4), 445-52.

Oxygen isotope values in metapelites including garnet-sillimanite gneisses (khondalites), quartzo-feldspathic gneisses (leptynites), cordierite-sapphirine gneisses and the associated marbles, calc-silicates, quartzites, basic granulites and charnockites from the Eastern Ghats Granulite Belt are presented and their significance discussed. Metapelites show a wide variation in δ¹⁸O values (4.50 to 13.90%0) that is controlled largely by the mineralogy of the rocks. Coarse grained prophyritic charnockites have higher δ¹⁸O values (8.60-11.20%o) than that of medium granited ones (5.90-6.60%o). Basic granulites have the minimum δ¹⁸O values (<126>5.0%o). Oxygen isotope values of different rock units in the granulite belt are constrained mostly by the composition of the source rocks of the sediments and of the protoliths in the case of charnockites. Post-depositional metamorphic and metasomatic fluids had little contribution to the δ¹⁸O variations in these rocks.

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003398   Rajendran K;Rajendran C P;Jain S K;Murty C V R;Arlekar J N (Centre for Earth Science Studies, , P B No. 7250, Akkulam, Thiruvananthapuram-695 031) : Chamoli earthquake, Garhwal Himalaya: field observations and implications for seismic hazard. Curr Sci 2000, 78(1), 45-51.

Chamoli earthquake in the northern part of Uttar Pradesh is an important event from the point of view of seismic hazard and risk assessment in the Himalaya. Tectonically, it is significant due to its location in the `central seismic gap', a 700-km-long segment between the 1905 Kangra (M 8.6) and the 1934 Bihar (M 8.4) earthquakes. Occurrence of two moderate earthquakes (1991 Uttarkashi and 1999 Chamoli) within a period of nine years naturally raises concern about the seismogenic potential of the region. Presents observation made during the post-earthquake survey around Chamoli, and address some issues regarding the regional seismic hazard.

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003397   Mukhopadhyay M (Department of Applied Geophysics, Indian School of Mines, Dhanbad-826 004) : Deep crustal structure of the West Bengal Basin deduced from Gravity and DSS data. J Geol Soc India 2000, 56(4), 351-64.

West Bengal basin (WBB) which developed at the margin of the eastern Indian shield in response to Gondwana rifting underlies a deep Gondwana trough covered by the Rajmahal (Cretaceous) basalts and younger sediments. Available crustal seismic, data for four profiles in southern half of the basin, as well as other available seismic drill-hole and gravity data, provide valuable information about the deep crustal structure and evolution of the WBB. The derived crustal model suggests significant mass anomalies in this part of the Indian palaecontinental margin. Rapid crustal thinning occurs along its eastern flank, where a denser lower crustal block is located adjacent to the Eocene `hinge zone' that separates the WBB from deeper parts of the Bengal delta. The intense zone of crustal necking below the WBB further bears a spatial relationship to the anomalous crustal layers and their attendant faults. The origin of these features is ascribed to the Gondwana rifting episode, resulting in the formation of a highly stretched crust at the Indian shield margin, where the Rajmahal volcanism eventually erupted.

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003396   Mukherjee A;Tripathi A;Singh P K;Babu E V S S K (National Mineral Development Corporation Limited, Khanij Bhawan, Masab Tank, Hyderabad-500 028) : Chemistry of Eclogitic garnets from Bahradih kimberlite, Raipur District,Madhya Pradesh. J Geol Soc India 2000, 56(4), 425-30.

Garnet concentrates from the Bahradih kimberlite pipe were analysed by electron microprobe and found to be mostly of the pyrope-almandine variety with significant amount of Na₂O and a pyrope content in the range of 48.76-61.45%, almandine 30.82-41.97% and grossular 2.313-9.983%, indicating eclogitic paragenesis. Their Mg# ranges from 53.92 to 66.59. The presence of traces of Na and T1 in these garmets indicates that substitution of these elements into the garnet structure is feasible at high pressure. Five out of 50 gamets analysed from Bahradih show Na₂ O=0.07 wt.% which indicates that they are from the diamond stability field, as confirmed further by the recovery of diamonds from the pipe.

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003395   Masroor Alam M;Ahmad A H M;Khan M H A (Geology Section, Department of Civil Engineering, Aligarh Muslim University, Aligarh-202 002) : Diagenetic features of lower Jurassic Lathi sandstones, Jaisalmer basin, western Rajathan. J Geol Soc India 2000, 56(4), 415-24.

The lower Jurassic Lathi Formation forms the lower part of the Jaisalmer basin and comprises 360 m thick succession of medium to coarse grained sandstones with interbeds of shale, claystone and occasional lignite. The rocks are exposed amidst desert and as low mounts and in shallow stone quarries. The sandstones were deposited in shallow marine to deltaic depositional environments. Deals mainly with the identification of various diagenetic features such as cements and their paragenesis, compaction, depth of burial and porosity evolution. The sandstones are marked by iron oxide, calcite, silica and dolomite cements. Compaction is mainly mechanical with a depth of burial in the range of 725-1125 m. The sandstones show good amount of porosity with an average of 13.3%. porosity reduction is mainly due to early stage of mechanical compaction and subsequent pervasive calcite and iron oxide cementation.

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003394   Mariappan P;Yegnaraman V;Vasudeven T (TWAD Board, , 38, Arunachalam Chettiar Street, Sekkalai, Karaikudi-630 002) : Control of fluoride content in the groundwater - scope for an interdisciplinary approach. Indian J envir Prot 2000, 20(6), 421-6.

Leaching of fluoride from the earth crust is the main process for the fluoride content in the groundwater. Observes that scope for the fluoride control in the groundwater by the method of blending, artificial recharge, efficient irrigation practice and proper well construction is bright.

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003393   Garg V K;Gupta R;Goel S;Taneja M;Khurana B (Department of Environmental Science and Engineering, Guru Jambheshwar University, Hisar-125 001) : Assessment of underground drinking water quality in eastern part of Hisar. Indian J envir Prot 2000, 20(6), 407-12.

Systematic study has been carried out to explore the physico - chemical characteristics of groundwater in eastern part of Hisar city, Haryana. A total number of 30 samples were collected from shallow hand - pumps of different localities. The quality analysis has been made through the estimation of pH, electrical conductivity, total dissolved salts, total hardness, total alkalinity, sodium, potassium, calcium, magnesium carbonate, bicarbonate, chloride and sulphate. On an average almost all the samples had one or the other chemical constituent beyond WHO permissible limits. A systematic calculation of the correlation coefficients has also been carried out between different physico - chemical parameters. The regression equations has also been developed between significantly correlated parameters.

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003392   Choubey V M;Ramachandran T V;Negi M S;Ramola R C (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001) : Calibration of radon emanometer. Indian J envir Prot 2000, 20(5), 329-31.

Presents the results of the laboratory calibration of radon emanometer for monitoring radon in soil and water. The detectors were calibrated in a standard radon calibration chamber and the results are reported. The efficiency of the detectors was found 77.6% which is quite comparable with the values reported by others. The calibration factor for radon was calculated as 1 count/min = 66.30 Bq/m³.

003391   Bhargava M;Pal A B (Hindustan Copper Ltd, , Malanjkhand-481 116) : Ci-Mo-Au metallogeny associated with proterozoic tectono-magmatism in malanjkhand porphyry copper district, Madhya Pradesh. J Geol Soc India 2000, 56(4), 395-413.

Ore mineral assemblages include Cu-Mo-Au with Ag and traces of Co. The veins are emplaced in shear zones in the granitoids, along schistosity planes in older schistosity planes in older schistose and gneissic rocks and at the contact of granitoids with Nandgaon volcanics. Most veins, basic dykes and microgranitoid intrusions occur in a 10 km wide zone of intense tectonic and magmatic activity. Hydrothermal alteration has affected the Malanjkhand granitoid. Alteration is stronger close to the mineralized veins. The alteration assemblages identified are potassic and propylitic. Potash metasomatism has produced K-rich zones close to mineralization. Pink granitoids contain higher amount of Fe₂O₃ compared to the gray granitoids. This is due to the presene of hematite introduced during potassic alteration. Alteration sequences and genetic models have been proposed, which can be used as guidelines for further exploration in the province. Mineralization associated with the granitoids at Malanjkhand and elsewhere in the region is of porphyry type. Various characteristics such as tectonic regime, association of I-type calc-alkaline granitoids, hydrothermal alteration, stockwork of mineralized veins, strong structural control, temperature of formation, huge tonnage and low tenor are features akin to various prophyry deposits of the world, especially those associated with plutonic rocks.

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003390   Ahmad S;Hasnain S I (School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067) : Meltwater characteristics of Garhwal Himalayan glaciers. J Geol Soc India 2000, 56(4), 431-9.

Comparative study of the meltwater chemistry from the Gangotri, Satopanth-Bhagirathi, Dokriani, and Bagni glaciers has been done for the late ablation period in October from 1991 to 1994. This late ablation period is characterized by low atmospheric input and lean flow in the glacier streams due to less availability of solar energy for supraglacial melting. During this period subglacial melting has played a dominant role in determining the water chemistry of glacier meltwater. The dominant controlling factor on meltwater chemistry has been rock weathering processes. The pH and electrical conductivity of the meltwater from these Himalayan glaciers ranged between 6.9-8.12 and 43-134.8 μS/cm, respectively. The purpose of this comparative study is to explain the geological control on the hydrochemistry of the meltwater draining from four different glaciers in the Garhwal Himalaya and to establish the relationship between meltwater hydrochemistry and the basement rock type.

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002220   Sinha R;Sharma C;Chauhan M S (Department of Civil Engineering, Indian Institute of Technology, Kanpur-208 016) : Sedimentological and pollen studies of lake Priyadarshini, Eastern Antarctica. Palaeobotanist 2000, 49(1), 1-8.

Shallow sediment core from a freshwater Antarctic Lake-Priyadarshini, in Schirmacher Oasis, Eastern Antarctica has been studied for grain size, mineralogy and pollen assemblage. The silty clayey sediments from the lake bed have a simple clay mineral assemblage consisting of illite and chlorite with dominant quartz and feldspar in clay-size fraction. A low-hydrolyzing, periglacial depositional environment is reflected from this assemblage. The pollen analysis identifies three pollen zones based on the fluctuations in the retrieved palynomorphs which apparently manifest palaeoclimatic oscillations during Holocene.

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