000107   Vumayoru Bhagan;Selvaraj V;Srirenganathan P (Department of Chemistry, S.T. Hindu College, Nagercoil-629 002) : Physico-chemical studies of water and sediments of AVM canal near Peninsular India. J Ecotoxic envir Monit 1998, 8(3&4), 268-8.

Anandan Victoria Marthandan Varma canal is an artificial canal of length 25 km and width 10 meters located in Kanyakumari district, southern most part of India. The physico chemical parameters of water and sediment samples such as turbidity, pH, electrical conductivity, dissolved oxygen, dissolved sulphide, free carbondioxide, total nitrogen, total phosphorus and potassium from four different stations along the course of the canal were studied. The results revealed that the values of physico-chemical parameters change seasonally.

000106   Singh V C;Mukherjee J K (NO, , ) : Forecasting of heavy/very heavy rainfall over Bareilly (UP) during SW monsoon. Vatavaran 1998, 22(1), 26-36.

Attempts has been made to study the synoptic situations leading to heavy/very heavy rainfall over Bareilly during the SW monsoon season. The interaction of a Western Disturbance with the axis of monsoon trough leading to its fluctuations across Bareilly from South to North and North to South or a low pressure area moving upto West UP either from East or from the West and strengthening of upper tropospheric Easterlis close to Bareilly are the favourable synoptic features. Along with these synoptic situation strong low level convergence, cyclonic vorticity, marked rised in TPW and vertical profile of θ_e are the other features indicated of heavy/very heavy rainfall over Bareilly after 24-36 hours.

000105   Shetye S R (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : West India Coastal Current and Lakshadweep high/low. Sadhana 1998, 23(5&6), 637-51.

West India Coastal Current (WICC) flows northward during November-February and southward during April-September. At the time of formation of he northward (southward) phase of the current, a high (low) in sea level - the Lakshadweep High (Low), forms off southwestern India, and migrates westward across the Arabian sea. The annual cycle of the WICC and that of the Lakshadweep High/Low arise from a set of circumstances that are special to the North Indian Ocean. This relatively small tropical basin is driven by seasonal monsoon winds. As a result, its wind-driven near-surface circulation consists primarily of annual and semi-annual long, equatorially-trapped Kelvin and Rossby waves, and coastally-trapped Kelvin waves. In terms of these waves, the West India Coastal Current is a superposition of annual and semiannual coastally-trapped Kelvin waves. The Lakshadweep High/Low forms when the Kelvin waves, on turning around Sri Lanka, and propagating northward along the west coast of India, radiate Rossby waves.

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000104   Pant B C;Shivhare R P (NO, , ) : Markov chain mode for study of wet/dry spells at AF Stn Sarsawa during SW monsoon season. Vatavaran 1998, 22(1), 37-50.

Daily precipitation data of Air Force Station, Sarsawa has been analysed with the help of Markov Chain Model to study the wet and dry spells. A day has been defined as wet when the rainfall has been 2.5 mm or more, otherwise it has been termed as dry. Using 19 years data (1976-94), the conditional probabilities have been worked out. The suitability of the first, second and third order Morkov models was ascertained by comparing the expected frequencies as per the models with the observed ones. It was found that the third order model is the best choice to simulate the wet or dry spells. The steady state probabilities and recurrence time of wet and dry days as per first order model were also computed and compared with 1995 data. They have been found to be realistically close to the observed values.

000103   Mishra S N;Mukherjee J K (NO, , ) : Forecasting of heavy to very heavy persistent rainfall occurrence over Adampur during south west monsoon season. Vatavaran 1998, 22(1), 1-10.

Attempts has been made to forecast the occurrence of persistent heavy to very heavy rainfall over Adampur, during South West monsoon season, atleast one day in advance. It is found that the presence of a well marked low pressure area over Gujarat and adjoining SW Rajasthan with trough extending Northwards upto Punjab, and well marked low pressure area over WMP and SE Rajasthan moving NW wards are favourable for occurrence of persistent heavy rainfall. The other useful synoptic features found to be are the presence of a WD over Punjab on lower levels, the passage of a slow moving trough in Westerlies at 300 hPa level between 68° E to 74° E and strong upper tropospheric Easterlies over NW parts of a country. Further, a near vertical profile of θe and the sharp increase in the TPW content upto 10.5 cm or more on day prior to occurrence give a very good indication of the forthcoming spell of persistent heavy to very heavy rainfall over Adampur.

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000102   Li J C (NO, Institute of Mechanics, Chinese Academy of Sciences, Beijing, 100080, China) : Overview of air-sea interface process studies. Sadhana 1998, 23(5&6), 631-5.

Recent progress in the study of air-sea interface processes for momentum, heat, moisture and mass transfer are reviewed. Except for turbulent structure, analysed the other physical mechanisms occurring in the wave boundary layer, such as the roles of the sea surface state, droplets and bubbles due to wave breaking, which at least partly account for the existing discrepancies between theory and observations. The experiments, both over the ocean and in the laboratory, are described briefly. In conclusion, a few perspective trends in this area are suggested for further investigation.

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000101   Krishnamurti T N;Jha B (Department of Meteorology, Florida State University, Tallahassee, FL 32306-3034, USA) : Cyclone track prediction. Sadhana 1998, 23(5&6), 653-84.

Authors address a number of modelling issues such as : explicit specification of the constant flux layer, cloud-radiative interaction and low cloud, cumulus parameterization, physical initialization, the ensemble of hurricane track forecasts and cloud forecasts. Among these the areas that have demonstrated the most sensitivity on tropical cyclone tracks, landfall and intensity are : resolution, cumulus convection, sea surface temperatures, soil moisture and orography around the ocean basin.

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000100   Krishnamurti R (NO, Geophysical Fluid Dynamics Institute, Florida State University, Tallahassee, FL 32306, USA) : Low frequency oscillations in turbulent Rayleigh-Benard convection. Sadhana 1998, 23(5&6), 605-13.

Locally time-periodic flow in Rayleigh-Benard convection in the range of Rayleigh number R of 10⁷ to 10⁸, Prandtl number 7, and aspect ratio 12 is reported. This time periodicity is associated with organized clusters of tilted plumes travelling steadily across the fluid layer. A scavenging plume model is presented in which prior passage of a plume has depleted the thermal boundary layer in a history-dependent way. The boundary layer is very thin where the plume has just passed, but has had time to thicken where the plume passed some time age. Thus at any moment there is a thermal boundary layer of varying thickness, and the pressure gradient in it drives flow towards the thicker regions. There is then a shear and a down-gradient momentum flux at the wall. This boundary layer is supposed to erupt when and where its thickness reaches some critical value. Then, assuming that the interior momentum flux is entirely by Reynolds stresses, by matching interior and boundary layer heat and momentum fluxes, determine the period which is shown to be in reasonable agreement with the observations.

000099   Cavaleri L (NO, ISDGM-CNR, San Polo 1364, 30125 Venezia, Italy) : Wave modelling and forecast. Sadhana 1998, 23(5&6), 615-30.

Discusses the main applications of wave modelling, namely the hindcast of past storms and their daily forecast for the next few days. The basic role of the input wind fields is discussed, together with the relationship between accuracy and grid resolution. After describing the results and accuracy achieved. Enumerates the expected developments in the near future.

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000098   Babu K S;Saxena R M (NO, , ) : On some aspects of onset of south west monsoon and its subsequent behaviour during 1993-97. Vatavaran 1998, 22(1), 11-25.

Dependence of Indian economy on agriculture makes the understanding, of SW Monsoon, vital. The two principal aspects of monsoon are its onset and its subsequent behaviour over the country. Although various LRF models are available, the field forecasters are handicapped due to non-availability of elaborate data base, to arrive at monsoon forecast with some degree of success. Using five (1993-97) years data in the monsoon season, a systematic analysis of the onset of monsoon over Kerala (MOK), its further progress and the underlying causes, was undertaken. Also a check of utility value of some of the well known regional parameters for forecasting MOK, was carried out for this period. It was evident that no particular feature on its own is responsible for either the MOK or its subsequent progress into the Northern parts of the country. The study of MOK and its influence on subsequent rainfall over the country, revealed that the MOK has no relationship with the quantum of rainfall over various sub divisions as well as the total rainfall over the country. The parameters which gave definite indication of MOK were identified and listed.

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024607   Venkatachary K V (NO, Indian Space Research Organization Headquarters, Bangalore-560 094) : Defining a space-based disaster management system for floods: a case study for damage assessment due to 1998 Brahmaputra floods. Curr Sci 2001, 80(3), 369-77.

Proto-type space-based disaster management system (DMS) has been organized with comprehensive database design, space-based near real-time monitoring/mapping tools, modelling framework, networking solutions and multi-agency interfaces. With the appropriate synthesis of these core elements, a system-definition of the frame-work of a DMS has been arrived at, in terms of developing a methodology towards damage assessment due to 1998 Brahmaputra floods. The limited validation experiments carried out in consultation with local level functionaries reveal that the experimental results on damage to agricultural crops due to floods are in conformity with field conditions. Still, there is a gap existing between the estimates arrived at and the estimates derived from conventional methods. It is herein that a concerted effort towards achieving absolute accuracy is called for. The conceived DMS ultimately aims at providing a holistic design and development of an information system, mainly to support the information needs for preparedness, prediction, damage assessment, rehabilitation and research; networking, mainly to be able to speedily provide access to the information system at any point of time from any place and decision, making, to support speedy and efficient decisions being taken, actions being implemented along with feedback mechanisms.

024606   Varma A K (Department of Applied Geology, Indian School of Mines, Dhanbad-826 004) : Thermogravimetric studies in characterization of coals from upper Silesian coal basin, Poland. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 4-5.

Thermogravimetric analyses (i.e. DTA, DTG and TG) it used for characterizing low and medium rank coals from Upper Silesian Coald Basin of Poland. The moisture content, volatile matter content and fixed carbon contents determined by the conventional standards and by the thermogravimetric methods, show a good correlation. Medium rank coals have higher values of thermogravimetric indicator, TI (proposed by Gabzdyl et al.) in comparison to low rank coals. Thermogravimetric indicator shows a good correlation with reflectance of vitrinite in oil (R°m vt). Therefore, it may also be used for rank determination of coal. Besides these, thermogravimetric studies of coals indicate decomposition course (under DTG and TG) as well as heat absorption-heat liberation pattern (under DTA) which may be used for prediction of coal behaviour during technological processes like coking, liquefaction, etc.

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024605   Uday Kumar;Sinha J (Department of Geology, Ranchi University, Ranchi-834 008) : Application of geostatistical tools in amphibolite petrogenesis : a case study of amphibolites of Ichadag, Ranchi (Bihar). Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 6-7.

Identification of primary magmatic or sedimentary source material for the genesis of amphibolities remains an enigma in the field of metamorphic petrology. The various geostatistical tools, viz. Trace element ratios, Chinnar's oxidation ratio and linear discriminant functions X1, X2 and X3 based on major and trace element composition of amphibolites help in identification of their ortho or para lineage. The amphibolites of Ichadag area, identified earlier as ortho amphibolites by petrographic and geochemical studies, have been tested for such compartmentalisation. The Sr/Ba= 1.62, Cr/Ni=2.63, average Chinner oxidation ratio=22.28 and Linear discriminant function X1=5.2, X2=4.8 and X3=1.4 confirms a basic magnatic instrusive as primary source material for these amphibolites.

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024604   Thiagarajan S;Ramana D V;Rai S N (NO, National Geophysical Research Institute, Hyderabad-500 007) : Seismically constrained two-dimensional crustal thermal structure of the Cambay basin. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 1-8.

The temperature field within the crust is closely related to tectonic history as well as many other geological processes inside the earth. There fore, knowledge of the crustal thermal structure of a region is of great importance for its tectonophysical studies. This work deals with the two-dimensional thermal modelling to delineate the crustal thermal structure along a 230 km long Deep Seismic Sounding (DSS) profile in the north Cambay basin. P-wave velocities obtained from the DSS studies have been converted into heat generation values for the computation of temperature distribution. The model result reveals the Curie isotherm at a depth of ≈22 km and Moho temperature at around 900°C.

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024603   Tewari V C (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001) : Sedimentology of Garbyang formation, Tethys Himalaya. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 25-6.

Grabyang Formation (Cambrian) unconformably overlies the Ralam Formation (Terminal Proterozoic) in Girthi Valley, Garhwal Tethys Himalaya. It is represented by biothermal grey limestone with large scale cross bedding herringbone cross-lamination and oolitic limestone. The presence of early Cambrian trace fossils and sedimentary structures suggests a high energy shallow marine depositional environment in interidal zone of a carbonate tidal flat. The microfacies and carbon isotopic values of the Garbyang Formation also support shallow marine sea water as depositional environment. Petrography of the Garbyang Formation from the type area in Kali valley reveals presence of zoned dolomite, radial and concentric oolites and stromatoporoids (calcified coccoids).

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024602   Tewari R C (Department of Geology, D S College, Aligarh-202 001) : Tectono-sedimentary significance of permian - triassic (p/Tr) boundary in east Gondwana. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 11.

Permian to Triassic transition in Gondwanaland province is marked by replacement of coal measures by red beds. A break in sedimentation is recorded at Permian-Triassic boundary in East Gondwana sector and also African rift basins. In Peninsular India, the sudden increase in coarse clastics in early Triassic of Pranhita-Godavari and Satpura, and shift in paleoslope from west to northwest in koel-Damodar basin indicate mild tectonic discordance close to Permian-Trassic boundary. Integrated geological and sedimentological evidence suggest a distinct episode of uplifts in most parts of East Gondwana at Permian-Triassic boundary.

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024601   Sreenivas B;Roy A B;Srinivasan R (NO, National Geophysical Research Institute, Hyderabad-500 007) : Geochemistry of sericite deposits at the base of the paleoproterozoic Aravalli supergroup, Rajasthan, India: evidence for metamorphosed and metasomatised precambrian paleosol. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 39-61.

Fine grained sericite deposits occur at the interface between Archean Mewar Gneiss Complex and the Proterozoic Aravalli Supergroup independent of shearing. They show a gradational contact with the basement granites and gneisses and a sharp contact with the overlying quartz pebble conglomeratic quartzites. Rip-up clasts of these sericite schists are found in the overlying conglomerates. The sericite shists are rich in sericite towards the top and contain chlorite towards the base. The sericite in these schists was formed by metasomatic alteration of kyanite and not from the feldspars of the basement granitoids and gneisses. Uni-directional variations of SiO₂ and Al₂O₃, high Al₂O₃ content (<62>30%), positive correlation between Al₂O₃ and TiO₂, Ti/Al and Ti/Zr ratios, high pre-metasomatic chemical indices of alteration (<62>90), and enrichment of heavy rare earth elements relative to the parent granites and gneisses-all these chemical characteristics combined with field evidence suggest that the sericite shists are formed from a paleosol protolith, which developed on Archean basement between 2.5 and <126>2.1 Ga in the Precambrian of Rajasthan. The superimposed metasomatic atteration restricts the use of Fe²⁺/Ti and Fe³⁺/T ratios of these paleosols for interpretation of PO₂ conditions in the atmosphere.

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024600   Sinha A K (NO, Birbal Sahni Institute of Palaeobotany, Lucknow) : Himalayan subduction and accretion tectonics of Karakoram block in central Asian mountain complex. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 20-3.

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024599   Singh K N (NO, , 530/101-A, Shekhaput, Lucknow-226 024) : Petrology of dudhatoli slab in parts of Chamoli and Pauri districts, Uttar Pradesh. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 3.

Metaflyschoidal sediments within gneissic complex of Dudhatoli, in parts of Almora, Chamoli and Pauri districts, Uttar Pradesh, display mineral assemblage of green schist to almandine-amphibolite-facies. They often contain bluish grey to greenish grey granulitic rock, used as roofing material and locally known as `Dudhatoli slab'. The rock is fine-to medium-grained, hard and compact and occurs as bands within stratiform gneissic bodies. The thickness and strike extensions of these bands are variable, as the rock merges with schist on one hand and quartzite on the other hand. The utilisation of these rocks as dimensional stone is ruled out on account of extreme variation of mineralogical composition both lateral as well as vertical and the tectonics to which they were subjected to. The polished blocks of the rock display very poor finish, lack of glossiness and reflectivity. Besides this, the colour is also not attractive and as such the rock is not viable for dimensional stone mining.

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024598   Singh A K (NO, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067) : Environmental geology of Damodar river basin : a tributary of the lower Ganga. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 28-9.

Water, bed and suspended sediment samples collected from the basin were analysed to study elemental chemistry and suspended load characteristics of the Damodar River basin. Water chemistry strongly reflects the dominance of continental weathering aided by atmospheric and anthropogenic activities in the catchment area. High concentrations of SO₄ and PO₄ at some sites indicate impact of mining and anthropogenic activity on water quality. The bulk sediment chemistry consists mostly (<62>70%) by the five elements Si, Al, K, Fe and Na, mean composition indicated that the Damodar sediments are depleted in Ca, Mg and heavy metals and enriched in Si and K as compared to the other Indian river basins. The concentrations of heavy metals in suspended sediments are significantly higher than the bed sediments. In general heavy metal concentration increases towards the finer size fractions. Speciation studies show that the lithogenic phase is the major sink for heavy metals. Fe-Mn oxide and organic fractions are the major nonlithogenic phases and Zn is the major constituent of the nonlithogenic phase.

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024597   Sikdar P K;Bhattacharya P (NO, Center for Study of Man and Environment, CK-II, Sector-2, Salt Lake City, Calcutta-700 091) : Assessment and management of groundwater resources in Puruliya district, West Bengal. Indian J Geol 2000, 72(1), 31-41.

Puruliya district is a part of Chhotonagpur Plateau and is underlain mainly by Precambrian metamorphics excepting a small area in the north-eastern part where Gondwanas are exposed. Groundwater occurs at shallow depth under water table condition within the weathered mantle, fractured hard rock and narrow zone of unconsolidated sediments, along major river valleys. The water table on an average lies within a depth range of 6-8 m bgl and 2-4 m bgl during the pre-monsoon and post-monsoon periods respectively. High fluctuation of water table is observed mostly in mice schist and Gondwana sediments. The groundwater potential of the district in 1995 (437.86 MCM) has fallen down by 81.84 MCM from that of 1978 (519.70 MCM). Future projection of groundwater balance reveals that there will be a marginal fall in the balance in 2001 A D (409.91 MCM). In some of the blocks the fall will be substantial whereas in others there will be an increase in the groundwater potential. It is envisaged that with phased construction of water harvesting structures in various blocks there will be an increase in the storage of surface water resources which in turn will augment the groundwater reserve.

024596   Shastry A;Srivastava R K;Chandra R;Jenner G A (Department of Geology, Banaras Hindu University, Varanasi-221 005) : Fe-Ti-enriched mafic rocks from south Andaman ophiolite suite: implication of late stage liquid immiscibility. Curr Sci 2001, 80(3), 453-4.

Andaman Ophiolite suite (AOS) is amongst one of the ophiolite complexes of the world, which comprises complete dismembered ophiolitic sequence. It consists of ultra-mafic and mafic cumulates, sheeted dykes, pillow lavas, felsic rocks (mainly plagiogranites), and sedimentaries including ribbon chert. A mafic rock that is highly enriched in FeO-TiO2 and encountered in the ophiolites of south Andaman is presented. Fe-Ti-enriched mafic rock is not yet reported from the south AOS. Genetically this rock may be associated with leucocratic rocks of AOS because it is experimentally proved that Fe-enriched basaltic melt and plagiogranite melt can be generated by late stage liquid immiscibility. Similar to most of the other plagiogranite occurrences of the world, Andaman plagiogranites are also supposed to be endproducts of magmatic differentiation of a mafic magma. But the discovery of Fe-Ti-enriched mafic rocks supports liquid immiscibility process.

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024595   Roy M (Department of Chemical Engineering, Science College, Calcutta-9) : Aerial oxidation of macerals and their extract at a low temperature an I.R. spectral study. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 5.

Aerial oxidation of Vitrinite, exinite and their extracts from a sample of Assam coal were carried out at 150°C and 200°C for different times. In case of vitrinite and its extract it is found that as the time and temperature of oxidation rise there is loss of aliphatic and aromatic hydrogen, the methyl and methylene groups gradually break down, the (CO) and (COC) groups decrease and the polycyclic aromatic skeleton breaks down, but the carboxyl group increases at the cost of aldehyde or keto groups. In case of exinite whose basic nucleus is less condensed than vitrinite, there is loss of hydrogen bonding and rupture of side chains as the time and temperature of oxidation rise. But there is formation of carboxylic groups and more carbonyl groups at the cost of aldehyde and keto groups. The polycyclic aromatic skeleton also breaks down as the time and temperature of oxidation rise.

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024594   Roy K K;Jaiswal P;Mukherjee A (Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur) : Two dimensional direct current resistivity finite element forward model. Indian J Geol 2000, 72(1), 61-75.

Two Dimensional direct current resistivity forward modeling is done using Finite element method. Rayleigh-Ritz energy minimization method for formulation of problem and Cholesky's decomposition were used to solve the finite element and symmetric, positive definite and sparse global stiffness matrix. Neumann's boundary condition, a natural boundary condition in the Finite element method in Poisson's equation domain was imposed on the problem for better accuracy. Finite element computational modules are presented and apparent resistivity profiles over vertical and dipping contacts and dyke are presented for resistive and conductive structures. The computer program utilizers an Object Oriented approach through C++ programming langauge in order to give the conventional algorithm a more real world approach. The authors also utilize the Object Oriented approach to partition, store and invert the Global Stiffness Matrix and demonstrate the reduction in time and storage space. The authors also propose formulation of a direct solver scheme that makes the potential computation independent of number of source positions.

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024593   Roy A K (Department of Geology, Asutosh College, Calcutta-700 026) : Provenance of the arsenic minerals associated with the quaternary alluvium of the Bengal basin. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 9.

Arsenic contamination of ground water of West Bengal, Tripura and Bangladesh is caused by the toxic aqueous solution derived from the hydrated alteration products of arsenopyrite buried in the quaternary alluvium of Bengal delta. The mineral had been transported, recycled and deposited with sediment by the southwardly and southeasterly flowing rivers in to Bengal basin from the zone of arsenic bearing polymentallic sulphide deposits at Samthar hills, Peshok, Chel, Garubathan etc. of the Darjeeling foot hills occupied by the metasediments of the precambrian Daling group and metavolcanics of mid-Tertiary age. High arsenic anomaly in ground water at places of Bangladesh north of the river Padma, geomorphically controlled fan pattern of the arsenic-affected region and composition of the heavy minerals with the arsenic rich mud form the bore hole samples of Paranpur, Murshidabad district and Mahisabathan, Nadia district recorded by A.K. Saha can be cited as some of the field evidences of transport of arsenic - bearing sediment from the Himalayan foot hills.

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024592   Raza M (Department of Geology, Aligarh Muslim University, Aligarh-202 002) : Geochemistry of jungel volcanics of Son valley, central India : evidence for and OIB-type alkali basalt volcanism during middle proterozoic. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 24-5.

Jungel volcanics are oldest known alkali basalts in Mahakoshal belt and adjacent areas in this region. Their chemical characteristics including IITE ratio spidergrams are closely similar to those of Middle Proterozoic alkali basalts occurring in Bafliaz volcanics of Himalayan region. The available geochemical data on mafic volcanic rocks of northwestern Indian shield indicate a time related change in the style of Proterozoic continental volcanism represented by Komatiite-tholeiite association in the early proterozoic (basal Aravalli) through tholeiite type in Middle proterozoic (basak Delhi) to tholeiite-alkali basalt association in the late-middle proterozoic (basal Vindhyan).

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024591   Ravi Shanker;Nag S;Ganguly A;Absar A;Rawat B P;Singh G S (NO, Geological Survey of India, Northern Region, Lucknow-226 024) : Are Majhgawan-Hinota pipe rocks truly group-I kimberlite. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 63-76.

The diamond bearing pipe rocks in Majhgawan-Hinota (more than four pipes) occur as intrusives in sandstones of Kaimur group. These Proterozoic (974±30-1170±20 Ma) intrusive rocks, occupying the southeastern margin of Aravalli craton, were called as `micaceous kimberlite' in tune with the reported kimberlite occurrences from other parts of the world. Judging from the definition of kimberlite, as approved by the IUGS Subcommission on Systematics of Igneous Rocks, it is not justified to call these rocks as `micaceous kimberlite'. Rather the mineralogical assemblages such as absence of typomorphic mineral monticellite (primary), abundance of phlogopite, frequent presence of barite and primary carbonate mostly as calcite coupled with ultrapotassic and volatile-rich (dominantly H₂O) nature and high concentration of incompatible elements (such as Ba, Zr, Th, U), low Th/U ratios, low REE and no Eu-anomaly clearly indicate a close similarity with that of South African orangeites. Thus orangeites of Proterozoic age occur outside the Kapvaal craton of South Africa which are much younger (200 Ma to 110 Ma) in age.

024590   Ramadass G;Ramaprasada Rao I B;Srinivasulu N (Central of Exploration geophyics, Department of Geophysics, Osmania University, Hyderabad-500 007) : Gravity inferred subsurface structure of Gadwal schist belt, Andhra Pradesh. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 25-32.

Detailed gravity data collected across the Gadwal schist belt in the state of Andhra Pradesh show an 8.4 mgal residual gravity anomaly associated with meta-sediments/volcanics of the linear NNW-SSE trending schist belt that shows metamorphism from green schist to amphibolite facies. This schist belt is flanked on either side by the peninsular gneissic complex. The elevation and slab Bouguer corrected residual gravity profile data were interpreted using 2-D prism Models. The results indicate a synformal structure having a width of 1.8 km at the surface, tapering at a depth of about 2.6 km with a positive density contrast of 0.15 gm/cc with respect to the surrounding peninsular gneissic complex.

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024589   Rais S (Department of Geology, Aligarh Muslim University, Aligarh-202 002) : Granulometric and morphometric characteristics of Talchir glacigenic clastics in parts of Son-Mahanadi Gondwana basin, Madhya Pradesh. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 12.

Granulometric study indicates that these rock samples have polymodal distribution and are poorly to very poorly sorted: The Talchir sediments have coarse to fine skewed and lepto-to platykurtic curves. Environmentally sensitive morphometric attributes like flatness and rounding indices, visual roundness and sphericity, of the embedded megaclasts, have been determined and plotted to understand their mutual relationship. The data suggest that the basal diamictite facies were deposited probably by ice sheet, whereas other diamictite facies were laid down by piedmont valley glaciers. The sandstone facies appear to have been deposited in fluvial environment. Morphometric study of the embedded megaclasts indicates close association with glacial and fluvioglacial environments. The study also suggests that there was more than one episode of glacial advancement in this part of Son-Mahanadi valley basin during Early Permian time, punctuated by glacio-lacustrine/fluvial (?) conditions.

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024588   Nageswara Rao G (Department of Meteorology and Oceanography, Andhra University, Visakhapatnam-530 003) : Occurrence of heavy rainfall around the confluence line in monsoon disturbances and its importance in causing floods. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 87-94.

It is well known that heavy rainfall occurs in the southwestern sector of the monsoon depressions due to strong convergence in that sector. By examining the rainfall distribution associated with the monsoon disturbances (low and depressions) in one of the central Indian river basins, `Godavari', the author found that when the disturbance- centre is away from the basin, heavy rainfall may also occur in the basin area close to the confluence line and cause severe floods in the river. The confluence line is the zone of convergence between the northeasterlies to the west of the disturbance centre and the monsoon westerlies. This study further reveals the importance of the position and movement of the confluence line with respect to the basin, on which the intensity and the raising period of the resulting flood depend.

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024587   Mukhopadhyay M;Mukhopadhyay M (NO, Indian Firebricks and Insulation Co. Ltd., P O Marar-829 117, Dist. Hazaribagh) : Refractory grade bauxite, its status and prospects in India. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 4.

Since the dawn of civilisation when fire was disiovered/necessity and requirement for refractories-an insulation cover to fire with time has progressed now it has been resolved that alumina-based refractories, either acid, basic or neutral area main the Backbone of the refractory system. The Alumina-based refractory being bauxite, as raw or as Calcined Bauxite or in any other processed from, is in regular requirement. The authors have been in this science for around twenty years now and are scared and apprehending dearth of refractory grade bauxite in India, unless some better alternate/processing is established to reducse Fe2O3/TiO2 content or to use bauxite having Fe2O3 and TiO2 Higher then 8-10% in totality.

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024586   Mishra N K;Sahoo H K (Department of Earth Science, Sambalpur University, Bural-768 019) : Lithostratigraphy of the precambrian rocks of Tileibani, Deogarh district, Orissa. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 13.

Detailed study of the field relations amongst various lithounits indicates that granitic rocks are intrusive into the banded biotite gneiss and are succeeded by outpouring of basic lavas. These are overlain by rocks belonging to Iron Ore Group which can be classified into two Formations viz. Clastic Formation lying below and Banded Iron-Formation lying above. The Clastic Formation is represented by quartzite, phyllite and quartz-sericite-schist whereas the Banded Iron Formation is represented by banded quartzite, banded cherty quartzite and banded hematite quartzite. All the available evidences indicate that the Iron Ore Group rocks are equivalent to the Older Iron Ore Group rocks of Orissa i.e. the Groumahisani Group.

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024585   Mishra J (Department of Geography, Magadh University, Bodh-Gaya) : Role of weathering in the evolution of Dome-gneiss and tors in the Madawar basin, Bihar. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 20.

Study area is a drainage basin formed by the master stream Madawar and its tributaries, spanning over 119.85 km² in the south-western part of Gaya district of Bihar. A large part of the basin is hilly and dissected. Most of the hills are dome-shaped and consist of granite and granite-gneiss of the Archaean Era. These beauty mingled hills have tors on them. Tors in utter confusion lying on the ground are not uncommon. The climate of the area is tropical continental monsoon type. Hence, weathering and running water are the main geomorphic processes responsible for the development of landforms. Assess the role of weathering in the evolution of dome-shaped hills and tors of the Madawar basin.

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024584   Mallick K;Sharma K K (NO, National Geophysical Research Institute, Hyderabad) : Finite element concept to derive isostatic residual maps - application to Gorda Plate and Sierra Nevada regions. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 33-8.

New space-domain operator based on the shape function concept of finite element analysis has been developed to derive the residual maps of the Gorda Plate of western United State. The technique does not require explicit assumptions on isostatic models. Besides delineating the Gorda Plate boundary, the residual maps exhibit a close match both in their anomaly patterns and magnitudes with previously computed residual maps based on the theory of isostasy.

024583   Krishnamurthi R (School of Studies in Geology, Vikram University, Ujjain-456 010) : Fluid inclusion and wall rock alteration studies of tungsten mineralization associated with Sewariya granite of Rajasthan. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 1-2.

Tungsten mineralization between Kalni (26° 30' N, 74°23'E) and Kotariya (26°23'N 74°16'E) in Sewariya region of South Delhi fold belt, Rajasthan is confined to fracture filled quartz veins and pegmatites within granite of along the contacts of granite and schistose enclaves. Detailed field work, mineralogical, geochemical and fluid inclusion studies were carried out to evaluate the physico-chemical parameters (p-T-X) of the mineralizing fluids and the nature of fluid-rock interaction during mineralization. Wolframite + ferrisicklerite + cassiterite are the main ore assemblage. Wall rocks adjoining mineralized veins exhibit an alteration association of sericite + quartz + tourmaline + topaz + K-feldspar + kaolinite due to fluid - granite interaction during vein formation. Fluid inclusions present in minerlized quartz samples have been classified into four main types and are NaCl - KCL - CO2 - H2O dominated hydrothermal brines derived from magmatic differentiation. Thermometric data indicate a temperature of 400°C-440°C for the formation of vein quartz.

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024582   Kishtawal C M;Basu S;Karthikeyan S (NO, Meteorology and Oceanography Group, Space Applications Centre, Ahmedabad-380 015) : Retrieval vertical wind profiles during monsoon from satellite observed winds over the Indian Ocean using complex EOF analysis. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 77-86.

Aim of this paper is to study the feasibility of deriving vertical wind profile from current satellite observations. With this aim, carried out complex empirical orthogonal function (CEOF) analysis of a large number of radiosonde observations of wind profiles over the Indian Ocean during the monsoon months. It has been found that the first two CEOFs explain 67% of the total variance in wind fields. While the first principal component is well correlated with the winds at 850 mb (r = 0.80), the second one is highly correlated with winds at 200 mb (r = 0.89). This analysis formed the basis of a retrieval algorithm which ensures the retrieval of vertical profiles of winds using satellite tracked acould motion vetor winds. Under the assumption that accurate measurements of wind are available at the above mentioned levels, the r.m.s. error of retrieval of each component of wind is estimated to range between 2ms^-1 and 6ms^-1 at different levels, which is much less than the natural variance of winds at these levels. For a better visualization of retrieval, authors have provided retrieved and true wind profiles side by side for four typical synoptic conditions during the monsoon season.

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024581   Kataki T (Department of Applied Geology, Dibrugarh University, Dibrugarh) : Diagenesis and porosity studies of sylhet limestone formation of Karbi-Anglong district, Assam. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 7-8.

Sylhet Limestone Formation (Eocene) of North-East India shows intensive diagenetic effects displayed by cementation, neomorphism, soclution leaching, silicification, pyritization and glauconitization. Two stages of diagenesis are recognized in the limestone. The earlier includes neomorphism, cementation and leaching followed by pressure solution, chemical activity, corrosion and replacement of calcite and vice-versa. Two stages of cementation are noticed : the early stage is marked by preponderance of non ferroan low magnesian calcite and the paucity of high magnesian calcite. The later stage is marked by the preponderance of low magnesian calcite.

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024580   Karanth R V;Das S (Department of Geology, M S University of Baroda, Vadodara-390 002) : Deformational history of the Pre-Champaner Gneissic Complex in Chhota Udepur area, Vadodara district, Gujarat. Indian J Geol 2000, 72(1), 43-53.

Proterozoic Pre-Champaner Gneissic Complex around Chhota Udepur of Eastern Gujarat consists of pelitic gneiss, schist and micaceous quartzite and granite gneiss. These lithounits show four phases of deformation wherein F1 and F2 are of isoclinal reclined nature. These two folds intersect at high angles. F1 folds are of buckle type and F2 folds are generated by flexural slip mechanism. Upright F3 folds are coaxial with F2 folds and are mutually perpendicular to F4 folds, which are open warps. F1 folds have general E-W trending axial traces whereas the F4 folds have NNE-SSW to N-S trending axial traces. These rocks have experienced high amphibolite facies metamporphism during first deformation as indicated by alignment of silimanite, kyanite and garnet along S1 whereas occasional recrystallisation of biotite, muscovite and kyanite took place during second deformation. The Champaner Group exhibits only F3 and F4 folds. F1 and F2 folds are typically absent in it. The conspicuous feature in this region is the change in the tectonic forces from D1 to D2 - D3. There is dissimilarity in the orientation of the folds of various generations between the study area, and the Aravalli Fold Belt proper. From the structural study, Chhota Udepur region apparently appears to belong to a separate tectonic regime and not related to Aravalli tectonism.

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024579   Kara P K (P G Department of Geography, Utkal University, Vani Vihar, Bhubaneswar-751 004) : Geographic information system : a tool for developmental planning. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 14-15.

Geographic information system is a powerful tool which needs complete understanding and careful application. The Remote Sensing Satellite provides an unbiased and synoptic view over a wide range of the electromagnetic spectrum. But more and more information is being maintained in Geographic information system efficiently store, retrieve, manipulate, analyse and display these data according to user-defined specifications. GIS has been called as an "enabling technology", because of the potential it offers of the wide variety of disciplines. As an intergrating field, GIS often claims to be the science of spatial information. GIS tools were originally developed to ease cartography. Geographic information system (GIS) with increasing use of physical inputs from Remote Sensing Data and conventional climatic, topographic and socio-economic data have revolutionised the information system for optimum resource planning and decision making.

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024578   Kanjilal S (Department of Geology, Banaras Hindu University, Varanasi-221 005) : Pteriacean bivalves from Jurassic rocks of Habo hills, Kachchh (Gujarat) : their mode of life and taxonomy. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 7.

Five different Pteriacean Bivalve taxa, including a new on (Pteroperna haboensis) are described, illustrated and discussed - all from the Callovian Middle Jurassic) to Oxfordian (Upper Jurassic) rocks of the Habo Hills in the Kachchh Mainland Gujarat. Their functional morphology is briefly analysed to interpret their likely mode of living and palaeoecology.

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024577   Jowhar T N (NO, Wadia Institute of Himalayan Geology, 33, General Mahadeo Singh Road, Dehra Dun-248 001) : BGT : a fortran 77 computer program for biotite-garnet geothermometry. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 6.

Fortran 77 computer program BGT is presented for calculating equilibrium temperatures of coexisting biotite-garnet paid. 20 different calibrations are incorporated into this program. Program BGT consists of Main program and 19 subroutines. It has been implemented on IBM PC compatible microcomputer using MD-DOS operating system.

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024576   Jai Krishna;Ojha J R (Department of Geology, B H U, Varanasi-221 005) : Intrabasinal correlations in the Middle Jurassic Callovian stage of Kachchh (Gujarat) and Ammonoid-foraminifer integration. Geophytology 1998, 28(1-2), 101-20.

Callovian sedimentary succession is nearly continuous and complete in the sections considered except in Ler (late Early Callovian to Late Callovian to Late Callovian part present) and Patcham (mostly Early Callovian part Present). In general the Early Callovian succession is found thicker than Middle or Late Callovian. The Bathonian/Callovian transition is displayed in the Patcham, Jumara and Jhura sections between the greyish white limestone and the overlying grey shales (Triangularis Zone/Madagascariensis Zone). The golden oolitic limestones are developed in the mid. Early Callovian (Chrysoolithicus Zone) only at Keera while similar looking limestone of Jhura and Patchman are found distinctly much older of late Middle to early Late Bathonian age. The earliest Early Callovian beds in Keera are non-oolitic below the golden oolitic limestone. The Early Callovian in other sections is mostly represented in the shale dominant facies with several thin, transgressive, nodular/concretionary levels of the 4th to 6th order para/mini/hemi depositional sequences (sensu Vail) rich in marine body fossils, mostly bivalves and ammonoids. Significant sand influxes are observed in the Patchman, Ler, Habo and Jhura sections in the relatively shallower and more proximal part of the basin in the north and east with precise beginning in the late Early Callovian Semilaevis Zone in contradiction to the late Middle Callovian or younger age suggested on the basis of benthic forams....

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024575   Iyengar R N;Agrawal S K (Department of Civil Engineering, Indian Institute of Science, Bangalore-560 012) : Earthquake source model using strong motion displacement as response of finite elastic media. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(1), 9-23.

Strong motion displacement records available during an earthquake can be treated as the response of the earth as the a structural system to unknow forces acting at unknown locations. Thus, if the part of the earth participating in ground motion is modelled as a known finite elastic medium, one can attempt to model the source location and forces generated during an earthquake as an inverse problem in structural dynamics. based on this analogy, a simple model for the basic earthquake source is proposed. The unknown source is assumed to be a sequence of impulses acting at locations yet to be found. These unknown impulses and their locations are found using the normal mode expansion along with a minimization of mean square error. The medium is assumed to be finite, elastic, homogeneous, layered and horizontal with a specific set of boundary conditions. Detailed results are obtained for Uttarkashi earthquake. The impulse locations exhibit a linear structure closely associated with the causative fault. The results obtained are shown to be in good agreement with reported values. The proposed engineering model is then used to simulate the acceleration time histories at a few recording stations. The earthquake source in terms of a sequence of impulses acting at different locations is applied on a 2D finite elastic medium and acceleration time histories are found using finite element methods. The synthetic accelerations obtained are in close match with the recorded accelerations.

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024574   Ghosh J G;Pillay K R;Dutta N K (G and IG Division, Geological Survey of India, 15, Kyd Street, Calcutta-16) : Geological note on the gold panning activity in the Kapsi-Lohattar area, Kotri linear belt, M P. Indian J Geol 2000, 72(1), 55-9.

Distribution pattern of gold panning activity by local gold panners along different streams of the Kapsi-Lohattar area of northern part of Bastar district is studied. From such study, the possible source rocks for gold is inferred. It is found that west of the Kotri river possible source rocks for gold are the two major quartz reef shear zones viz., the Dorde Kaddar Shear Zone and the Pachangi Shear Zone and also some locally present are senopyrite bearing rhyolite and tufaceous layers. East of the Kotri river, possible source rocks for gold are the conglomerate units of the Patkasa Formation which forms an younger sedimentary cover over the volcano-sedimentary rock suite of the Kotri Supergroup. Gold present in this Formation could represent paleoplacer deposit. The BIF of the Latmarkarka Formation could also be a source.

024573   Gaur V K (NO, Indian Institute of Astrophysics, Koramangala, Bangalore-560 034) : Rann of Kachchh earthquake, 26 January, 2001. Curr Sci 2001, 80(3), 338-40.

024572   Casshyap S M;Khan A (Department of Geology, Aligarh Muslim University, Aligarh-202 002) : Depositional models of Denwa and Bagra formations in Satpura Gondwana Basin of Central India, M P. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 10-11.

Denwa (Late Early-Middle Triassic) and Bagra (Late Jurassic-Early Cretaceous) formations of Satpura basin central India exhibit a contrasting stratigraphic relationship, paleocurrent pattern and petrography. The Denwa Formation (300 m) conformably lies above the Pachmarhi formation and unconformably overlain by the Bagra Formation. Stratigraphic relationship, lithofacies, petrography and paleocurrents evidently suggest a meandering streams depositional model for Denwa and alluvial fan model for the overlying Bagra Formation. An abrupt change in fluvial model from meandering to alluvial fan from Late Early and Middle Triassic to Late Jurassic-Early Cretaceous suggest a major tectonic and reversal of paleoslope to provide coarse and fine sediments to the Bagra Formation from north to south after Denwa which resulted in uplifting of the source area to the north-northeast of Satpura basin, where Vindhyan and Bijawar are now exposed. Indeed, the tectonic uplift in this part of Peninsular India was related to the succeeding tectonic event of widespread eruption of Deccan Traps.

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024571   Bhuyan D;Borgohain R;Dutta S K;Kalita C K (Applied Geology Department, Dibrugarh University, Dibrugarh-786 004) : Heavy mineral assemblages of the Langpar formation from the subsurface of parts of Dibrugarh and Tinsukia districts, Upper Assam Shelf. Geophytology 1998, 28(1-2), 1-10.

Langpar Formation of Upper Assam Shelf of Dibrugarh and Tinsukia districts contains heavy mineral assemblage comprising zircon, tourmaline, rutile, hornblende, hypersthene, garnet, epidote, augite, enstatite, apatite and opaque minerals such as magnetite hematite, ilmanite and pyrite. There is a distinct trend in distribution of some species of these minerals. The occurrence of hypersthene in the Early Tertiary rocks is significant. These heavy minerals show wide range in the maturity index value that suggest that these sediments have varying compositional maturity. The mineralogical maturity on the NE and SW of the Rajali Well is distinctly different, indicates derivation from different sources. It is concluded that these sediments were derived from igneous, metamorphic and reworked sediments.

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024570   Baruah H;Das P K (Department of Geological Sciences, Gauhati University, Guwahati-781 014) : Textural behaviours reflecting depositional environment of the Tura sandstone in and around Tura, east Garo hills, Meghalaya. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 8-9.

Grain Size analysis of the Tura Sandstones shows it as unimodal, mainly medium grained, well to moderately well sorted, slightly to negatively skewed and mainly moderately peaked, thereby implying a lower energy of the system with very little variation in between Grain accumulation was largely media controlled with lesser influence of the source. The "sand" distribution shows the impact of both beach and fluviatile environments in the bivariate discrimination plots. C-M plots indicate mainly rolling with minor suspension and this substantiates the distribution's graded nature. However, somewhat better sorting and sediment transport by saltation are brought out by the Log Probability plots indicating a fluviatile nature. Considering the influence of both beach and river, a shelf environment may be projected in this case where the fluviatile influence was more dominant.

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024569   Acharya S;Singh P;Das M;Sahoo N K;Acharya D (NO, , V I P Colony, Nayapalli, Bhubaneswar) : Chromite and magnetite occurrences around Moulabhanj area, Dhenkanal district, Orissa. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 2-3.

Chromite and magnetite hosted within the mafic-ultramafics occurs in and around Moulabhanj (20° 45' : 85°52') in Dhenkanal district, Orissa. The ore bearing bodies have invaded into the garnetiferous granite-gneisses and granulites of Eastern Ghats. The chromitites are massive, banded and spotted in nature. The chromite grains exhibit cumulus, chain, exolution and cataclastic features. Magnetite (titanomagnetite) along with ilmenite and are also observed. Hogbomite is noted for the first time. The textural, structural and field relations lead to surmise that the chromitite bodies belong to the Precambrian stratiform type and subsequently deformed. The deposits are considered genetically as one with the Sukinda chromite-bearing ultramafics.

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024568   Acharjee S (Department of Geology, Cotton College, Guwahati-781 001) : Enclaves in Nongpoh granite, Ri-Bhoi district, Meghalaya : pe-trology, petrochemistry and petrogenesis. Proc Indian Sci Congr Ass - Pt III(YS abstr), Sect-I 1998, (NULL), 29-30.

Enclave suite in Nongpoh Granite comprises of Hornblende-Biotite-Schist (HBS), Pyroxene-Hornblende-Biotite-Diorite (PHBD), Granite Gneiss (GG) and False enclaves like Micaceous schleirens. HBS and GG has a sharp contact while PHBD has a diffused contact relationship with the enclosing granite. Mineral parageneses points to amphibolite facies metamorphism for the enclave suite. Selected samples have been analyzed for their major and trace element compositions. A tholeiitic character for HBS and PHBD and a Calc-alkaline character on GG is evident. The rocks and Fe enriched and the decreasing concentration of silica with increasing total iron is consistent with Fenner trend fractionation. A igneous derivation for PHBD and sedimentary derivation for HBS and GG is predicted from Niggli value plots.

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