020282   Guha D B (NO, Geological Survey of India, Jhalana Dungri, Jaipur-302 004) : Petrogenesis and tectonic setting of the Bari Lake-Lakhawali volcanics and the Ahar river granite around Udaipur, Rajasthan. Bull Indian Geol Ass 1997, 30(1-2), 7-19.

Bari Lake-Lakhawali volcanics in the Aravalli Fold Belt near Udaipur, forming the Bari Lake Group, is geotectonically coeval with the initiation of early Proterozoic Delwara volcanism and formation of the Aravalli basin. The Bari Lake-Lakhawali volcanics range from basalt to dacite with an iron enrichment and tholeiitic (arc, within plate) trend. Various chemical and tectonic diagrams supported by field characters suggest their eruption in an island arc set-up. The Ahar River Granite shows calcalkaline trend, metaluminous to peraluminous composition, with a distinctive POG character having island arc affinity. The granite melt is considered to have generated between 650°C to 685°C at 5 Kb water pressure coexisting with quartz + alkali feldspar + plagioclase. The volcanics and the granite association in space and time are inferred to form Proterozoic granite-greenstone sequence in the Aravalli Fold Belt which evolved as a result of plate convergence along Rakhabdev suture in island arc-continent collision set-up.

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020281   Ghosh U;Chowdhary P K;Pathak K M (NO, Shillong College, Shillong-793 003) : Evolution of rubidium, strontium and initial strontium isotopic ratios in the porphyritic granites of Assam-Meghalaya plateau. Bull Indian Geol Ass 1997, 30(1-2), 83-7.

Rb-Sr whole rock isochron ages of the porphyritic granites from different granite bodies of Shillong plateau range from 260 to 690 m.y. However, fission track mineral dates are nearly the same for the granites of different bodies. An analysis of the published Rb-Sr data indicates sequential adding of Rb and Sr in the granitic magma. An empirical relationship between initial 87_sr/86_sr ratios suggest that the magma was contaminated with the crustal rocks and has undergone fractional crystallisation.

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020280   Ghosh S K;Rohtash Kumar (Sedimentology Group, Wadia Institute of Himalayan Geology, P.O. Box 74, Dehra Dun-248 001) : Petrography of neogene siwalik sandstone of the himalayan foreland basin, Garhwal Himalaya: implications for source-area tectonics and climate. J Geol Soc India 2000, 55(1), 1-15.

Neogene fluvial sandstone (Middle Siwalik; 9- 5.23 Ma) in the Dehra Dun sub-basin (west central sector of Himalayan Foreland Basin) is characterised by distinct grey colour, and salt and pepper texture. They can be divided into poorly indurated (friable), Matrix-Rich Sandstone (MRS) and indurated (hard), Matrix-Poor Sandstone (MPS). The sandstone is classified as lithic arenite (Q₅₅F₅R₄₀; Mx₂; 50%), lithic graywacke (Q₆₁F₃R₃₆ Mx₂₄; 29%) and sublithic arenite (Q₇₅F₅R₅₀Mx₃; 21%). The MRS is fine-to very fine-grained lithic graywacke, and the MPS is medium to fine-grained lithic to sublithic arenite. The framework composition of the sandstone points to its derivation from a provenance comprising sedimentary, low to medium grade Metamorphic and igneous source rocks. Significant increase of metamorphic element above 750m level (7.65 Ma) and particularly from 900m level (7.50 Ma) suggests a widespredad erosion of the uplifted Himalayan gneiss or the Higher Himalayan Crystallines (HHC). The uplift of Higher Himalayan Crystalline was due to tectonic adjustment along the Main Central Thrust (MCT) between 7.65 - 8.50 Ma. However, a distinct deviation from semi-arid to humid climatic phase is observed between 8.5 and 7.6 Ma.

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020279   Chaudhuri B K;Gururajan N S (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001) : Sheath folds in the Munsiari crystallines, Alaknanda valley of the Garhwal Himalaya. Geosci J 1999, 20(1), 87-91.

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020278   Biyani A K (NO, D.B.S. (P.G.) College, Dehradun-248 001) : Petrology and barrovian type metamorphism of the higher himalayan metapelites of the Yammuna valley, district Uttarkashi (U.P.). Bull Indian Geol Ass 1997, 30(1-2), 61-9.

Highly attenuated homoclinal nappe sheet of 1.0 to 1.5 km vertical thickness of Central Crystalline Zone in the Higher Himalayan, Yammuna Valley shows Barrovian type of metamorphism. The greenschist metapelites are rich in silica, iron and potash but deficient in alumina, magnesia and lime. The index minerals, biotite and almandine appear to have formed by more than one reaction. Presence of K-feldspars have also been noted in the chlorite zone. The metamorphic rocks reveal three events of metamorphism : M₁ (prograde and Barrovian type), M₂ (mild and of short duration) and M₃ (retrogressive) and two episodes of deformations D₁ and D₂. The observed mineral assemblages yield temperature of 500°C and H₂O pressure of 4.5 to 5.2 Kb. The peak PT conditions of metamorphism attained during M₁ event.

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020277   Bhoskar K G (Geological Survey of India, , Seminary Hills, Nagpur-440 006) : Genetic modelling in relation to the Geochemical parameters of distribution of tungsten and associated metals in a submarine basic volcanic domain - a case history of Ranbori - Bhaonri prospects. Gondwana Geol Mag 1998, 13(2), 13-21.

Elucidates details of localisation of tungsten mineralisation, dominantly in a submarine basic volcanic suite in Bhaonri area of palaeo-Proterozoic Sakoli Group in central Indian Shield and the influence of sea-bed hydrothermal activity on the geochemical characteristics of the formation. The hydrothermal activity comprises wsidespread silicification, felspathisation, epidotisation and formation of exhalates viz. coticules. The formations comprise chlorite phyllite, carbon phyllite and coticules, amphibole bearing cherts, all closely associated and interlayered with metabasalts and diabase sills. Pelitic schists and rhyolitic tuffs occur in the adjoining area. The rocks are highly deformed and have a NW-SE trend. Mineralisation of tungsten, mainly as scheelite has been observed over a strike length of about 5 km, roughtly in NW-SE direction and has been established by exploratory drilling. Mineralisation is observed in two enechelon lenses parallel to bedding/foliation having a 1.5 km length at Bhaonri and 1.2 km length at Ranbori. Major lense of mineralisation is lofcated in the metabasalt along a zone of hydrothermal alteration which is evidenced by felspathisation, epidotisation, silicification, chloritisation and carbonitisation etc. Mineralisation is also noted along a second lense in the coticules interlayered with the volcanics (tholelitic basalts) and associated tuffaceous sediments. Geochemical parameters of distribution of W, Cu, Pb, Zn, Sn, Nb, Ta, V, Cr, Ni, Co etc. have been studied in detail from samples of coticules and metabasalts....

020276   Bhaskara Rao D;Mohan Rao C P V N J (Department of Geophysics, Andhra University, Visakhapatnam-530 003) : Two-dimensional interpretation of gravity anomalies over sedimentary basins with an exponential decrease of density contrast with depth. Proc Indian Acad Sci-Earth Planet Sci 1999, 108(2), 99-106.

Decrease of density contrast with depth in sedimentary basins is approximated by an exponential function. The anomaly equation, in frequency domain, of a prismatic model with an exponential density function is derived. The method has been extended to derive the Fourier transforms of the gravity anomalies of the sedimentary basin, wherein the basin is viewed as vertical prisms placed in juxtaposition. The gravity anomalies of the sedimentary basin are obtained by taking the inverse Fourier transforms. Filon's method has been extended for calculating accurate inverse Fourier transforms. The accuracy of the method has been tested using a synthetic example. A combination of space and frequency domain methods have been developed for inversion of gravity anomalies over the sedimentary basin. The method has been applied to interpret one synthetic profile and one field profile over the Godavari basin. The method developed in this paper to calculate the inverse Fourier transforms yields continuous spectrum with accurate values. The maximum depth deduced from the gravity anomalies is of the same order as the depth encountered to the basement at the Aswaraopeta borewell.

020275   Banerjee S N;Majumder S;Ghosh R N (Geological Survey of India, , Calcutta-700 016) : Continental N-Q boundary in the eastern margin of peninsular shield, West Bengal, India. Gondwana Geol Mag 1998, 13(2), 35-46.

To establish the Neogene-Quaternary boundary along the eastern margin of the peninsular shield, West Bengal by synthesising the data obtained by various workers while carrying out mapping and mineral investigations in Purulia, Birhum, Bankura, Bardhaman and Medinipur districts and correlating the same with the Neogene-Quaternary boundary established in the Lalgarh Section of Kasai basin, Medinipur district.

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020274   Ashalatha B;Singh R N (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Fractal analysis of bathymetry and gravity profiles across the Chagos-Laccadive Ridge and the Carlsberg Ridge in the Indian ocean. Proc Indian Acad Sci-Earth Planet Sci 1999, 108(2), 81-5.

Gravity and bathymetry data have been extensively used to infer the thermo-mechanical evolution of different segments of the oceanic lithosphere. It is now understood that magmatic fluid processes involved in the accretion of oceanic crust are spatially complex and episodic. The nature of these processes which are in general nonlinear, can be described using fractal analysis of marine geophysical data. Fractal analysis has been carried out for gravity and bathymetry profiles over the aseismic Chagos-Laccadive Ridege and the spreading Carlsberg Ridge. The Iterated Function Systems (IFS) have been used to generate synthetic profiles of known dimension (D) and these are compared with the observed profiles. The D for the data sets are in the range of 1-1.5. The D for gravity profiles is less than those of bathymetry and the D for gravity and bathymetry over spreading ridge is higher than the aseismic ridge. The low fractal dimension indicates that the processes generating them are of low dimensional dynamical systems.

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020273   Arunmurty T V S;Wakde S D;Murthy V R (Department of Physics, SSGM College of Engineering, Shegaon-444 203) : Diamagnetic susceptibility and polarizability of some nematogens. Asian J Phys 2000, 9(2), 360-1.

Diamagnetic susceptibilities and polarizabilities of closely related compounds, p-methoxyphenyltrans-4-pentylcyclohexane carboxylate and p-propoxyphenyltrans-4-pentylcyclohexane carboxylate, are reported using molecular vibration approach and modified Lippincott delta-function potenitial model. The diamagnetic susceptibility and polarizability calculated for the chosen system are found to be in good agreement with the literature values.

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020272   Alam M M (Deptt of Geology, A.M.U., Aligarh-202 002) : Petrographic study of the malani volcaniclastics of Jodhpur area, western Rajasthan, India. Bull Indian Geol Ass 1997, 30(1-2), 55-60.

Jodhpur area in western Rajasthan is a type area for eastern reaches of the Malani igneous suite and offers a good opportunity to study felsic volcaniclastic facies. This has been the subject of intensive and extensive study by the author and the results of the study are summarised. Six volcaniclastic facies in the area are distinguished on the basis of field and petrographic characters. The facies include ignimbrite, laminated tuff, massive tuff, agglomerate, autoclastic breccia and epiclastic tuff. The rocks show typical pyroclastic field and petrographic characters, such as volcanic bombs, eutaxitic texture, lithophysaes and glass shards with typical cuspate forms, the main pyroclastic processes which deposited the different facies include pyroclastic flow, fall, lava--water interaction and reworking of volacniclastics. The facies association suggest sub-aerial phreato-plinian type of eruption.

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020271   Agnihotri S K (Geological Wing, Government of Himachal Pradesh, , Udyog Bhawan, Shimla-171 001) : "Maseran member" - a distinct lithounit at the base of the shali group in Himachal Pradesh. J Geol Soc India 2000, 55(1), 91-5.

Detailed geological mapping in the Drang area, Mandi district, Himachal Pradesh combined with traverses and sub-surface exploration reveal that a horizon consisting of calcareous grit having quartz grins in acarbonate cement and recemented brecciated limestone lenses, is best exposed at Maseran Temple Hill undrlying the lokhan lithounit of the Ropri Formation. It forms the oldest umitof the Shali Group, occurring in the basal part of the Ropri Formation and is named as the Maseran Member.

019081   Tiwari D R (Department of Geology, Govt. Motilal Vigyan Mahavidyalaya, Bhopal) : Physicochemical studies of the upper lake water Bhopal, Madhya Pradesh, India. Pollut Res 1999, 18(3), 323-6.

Reports water quality of upper lake of Bhopal based on a short term study water quality was found to be suitable for irrigation and drinking based on physico-chemical factors.

019080   Thussu J L (Geological Survey of India, Central region, , Nagpur) : Geoenvironmental appraisal of Haryana. J Geol Soc India 1999, 54(6), 621-40.

Haryana primarily an agricultural State, is rapidly transforming into an industrial State Most part of the area in the State is occupied by vast stretches of Quaternary Alluvial plains separating the rocks of Delhi Supergroup in the south and west and Siwalik in the northeast. Various geomorphic landforms have been identified. Central Alluvial Plains occupy about ninety five percent of the total area of the State while the hard rocks are exposed only in five percent of the total area. Based on geological, geomorphological set up and geochemical studies, it has been possible to conclude that the potential environmental hazards distinctly differ in each land form. Two types of environmental hazards, viz., natural hazards and biotic or anthropogenic hazards have been recognised. The natural hazards, viz., salinity, salt effcorescence, sand remobilisation, bad land and water logging mainly affect the Central Alluvial Plains, while biotic or anthropogenic hazards, viz., mining, quarrying, wastage disposal, leakage from canals and excess drawal of water affect all the geomorphic landforms. Effective management controls have been suggested to mitigate the natural hazards and proper planning measures to control biotic hazards.

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019079   Raval U (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Some recent geophysical constraints from the Central Gondwanaland. Proc Indian Natn Sci Acad-Pt A 1999, 65(3), 209-60.

Recent geophysical data from parts of Greater India consisting of India, Madagascar and Seychelles is reviewed. On the basis of the separation history of various regions of the Gondwana supercontinent, it is proposed that Greater India could be termed as Central Gondwanaland Deep crustal structural and geophysical characteristics of the Precambrian Indain continental lithosphere and Madagascar have been described on the basis of available data. Possible reactivation of the mobile parts of the continental lithosphere due to rifting, plume activity and associated geodynamical processess have been discussed along with palaeopositions. The crustal structure beneath Madagascar as deduced from gravity and teleseismic studies has been outlined. The paper also gives the structural elements, potential field signatures and the seismic stratigraphy in the Bay of Bengal and the Arabian Sea. A special emphasis has been placed on the intraplate deformation zone of the Central Indian Ocean with regard to some recent results as well as the concepts which have been put forth to understand the geodynamics of this region.

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019078   Rao V P;Rao N V (Centre of Exploration Geophysics, Osmania University, Hyderabad-500 007) : On the calibration of a scintillometer for insitu measurement of radioactivity for geological and environmental studies. Radiat Prot Envir 1999, 22(1-2), 43-8.

Gamma ray technique using portable scintillometers has been one of the most important methods for surveying natural radiation environment. However, the major thrust of application of the method so far has been only in the exploration of uranium deposits and its importance in geological mapping has been realised only recently. In view of its potential, studies were undertaken on the development of the method (Purushotham Rao, 1998). Results of these studies on calibration, optimisation and standardisation of a portable scintillometer for insitu measurements are presented.

019077   Prasad K S S;Raju A N;Nayudu P T (Department of Geology, S.V. University Tirupati, ) : Role of volatiles in the formation of pegmatites Nellore schist belt, Andhra Pradesh. Ultra Scient phys Sci 1999, 11(3), 361-5.

Metamorphogenic-magmatic theory of origin of pegmatite supposes as essential homogenization of granitized rocks and does not exclude the supply of some components like alkalies and olatiles. Thus the differentiations of silicate melt and derivation of pegmatities takes place during the post-metasomatic processes and the interaction between pegmatites and their wall rocks.

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019076   Nair M R;Malshe V C (Plastics and Paint Department, UDCT, Matunga-400 019) : Alternate chemistries for film formation. Paintindia 2000, 50(1), 35-42,50.

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019075   Mishra M;Rajamani V (NO, School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067) : Significance of the archaean bimodal volcanics from the Ramagiri schist belt in the formation of Eastern Dharwar craton. J Geol Soc India 1999, 54(6), 563-83.

Central arm of the trident shaped Ramagiri schist belt includes a central block which consists predominantly of bimodal (mafic-felsic) volcanics, apart from minor metasedimentary units. The geological set up of the various rock types suggests that the central block could be a tectonic melange. The metaholeiites and the felsic volcanics of the central block show similar LREE - enriched and fractioned REE patterns; the metatholeiites however, show a much larger variation in abundances. It has been suggested that the protoliths to the Ramagiri central mafic suite of bimodal volcanics were formed by different extents of melting of the metasomatically enriched mantle sources and were emplaced in an island are setting. The partial melting of similar metaholeiites, constituting an arc crust, at <126> 8 kbar pressures and at <126> 1000°C temperatures, produced magmas to the associated felsic volcanics. The geochemical characteristics of the maffic and felsic volcanic rocks in the Ramagiri belt, as well as the adjoining Sandur belt, have many similarities to those of the modern day island arc volcanic suites. The idea that the Phanerozoic style magmatic and accretionary tectonic processes operated during the Late Archaean suggested from the studies of granitic rocks in the Eastern Dharwar craton is corroborated by the metavolcanics of the Ramagiri schist belt.

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019074   Madhavaraju J;Ramasamy S (Sedimentology Lab, Department of Geology, School of Earth and Atmospheric Sciences, University of Madras, Guindy Campus, Chennai-600 025) : Microtextures on quartz grains of companian - Maastrichtian sediments of ariyalur group of Tiruchirappali cretaceous, Tamil Nadu - implication on depositional environments. J Geol Soc India 1999, 54(6), 647-58.

Quartz grains of the Campanian-Maastrichtian sediments of the Ariyalur Group of Tiruchirapalli Cretaceous, Tamil Nadu, using Scanning Electron Microscope (SEM) have brough out nineteen distinct microtextures. They have been grouped into features based on their mode of origin. Of these, thirteen are of mechanical and five mechanical and/or chemical origin while one distinctly chemical. The quartz grains of the Ariyalur Group sediments show a wide range of conchoidal fractures, straight steps and arcuate steps formed during the liberation from the metamorphic and igneous source rocks. The microtextures - v's, pits, straight and curved scratches are characteristic of the marine environment. The frequency of these features is higher in the grains from the Sillakkudi, Kallankurichchi and Ottakkovil Formations. Rarity of these features on quartz grains from the Kallamedu Formation is suggestive of variation in transport and depositional conditions. It has been inferred from the microtextures that the source for the quartz grains in the Ariyalur Group sediments has been nearly Precambrian crystalline basement.

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019073   Lalmani;Babu M K;Rajou Kumar;Rajesh Singh; Gwal A K (Department of Physics, Engineering College Srinagar, Camp Jammu Canal Road, Jammu-180 001) : VLF saucers recorded at low-latitude ground Station Jammu. Ultra Scient phys Sci 1999, 11(3), 381-2.

Phenomenon of (LLVEs) of VLF `saucer' has been recorded at low latitude ground station Jammu (geomag lat 22°26'N) for the first time on February 18, 1998 between 1200 IST-1800 (Indian Standard time) and been discussed.

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019072   Kousalya M;Seshunarayana T;Prasad P P (NO, National Geophysical Research Institute, Hyderabad-500 007) : Environmental vibration studies at Charminar. J Geol Soc India 1999, 54(6), 641-46.

Measurements of vibrations caused by vehicular traffic around Charminar, a monument at Hyderabad, was carried out using three component velocity sensors and high-resolution digital seismograph. These measurements were done at different levels viz., ground, middle, top level and at other accessible levels of the structure. Acceleration and displacement were computed from the velocity-time series. Peak particle velocity was found maximum at the top level in the north-south direction.

019071   Iyer S D (Geological Oceanography Division, National Institute of Oceanography, Dona Paula, Goa-403 004) : Alteration of basaltic glasses from the central Indian ocean. J Geol Soc India 1999, 54(6), 609-620.

Textural, mineralogical and compositional characteristics of basaltic glasses from the Central Indian Ocean show them to be altered to varying extents through their interaction with the seawater, resulting in the formation of palagonite. The major chemical changes are the loss of Si, Mg and Ca and a gain of Na and K whilst, Fe and Ti remained immobile. It reflects that the basaltic glasses have undergone initial to intermediate stages of palagonitisation under low temperature oxidative alterations. Subsequent accretion of ferromanganese oxides over the glasses have halted the progress of alteration.

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019070   Dessai A G;Knight K;Vaselli O (Department of Geology, Goa University, Taleigao Plateau, Goa-403 206) : Thermal structure of the lithosphere beneath the Deccan trap along the western Indian continental margin : evidence from xenolith data. J Geol Soc India 1999, 54(6), 585-98.

Late alkaline lamprophyre - intrusives from the Deccan Trap along the western Indian continental margin entrain rare granulite and pyroxenite xenoliths some of which contain kaersutite ± phlogopite ± apatite ± scapolite ± sulphides providing evidence of fluid induced metasomatism. P-T estimates on carefully selected mafic granulite and pyroxenite xenoliths define a palaeogeotherm from 550°C, 5 kb to <126>830°C, 8.5 kb for the Mumbai region along the western continental margin. This elevated geotherm suggest advective heat transfer from magmas ponded near the crust mantle boundary. Xenolith petrology coupled with seismic data suggests that the lower crust beneath Mumbai consists of mafic granulites under - and intra-plated by pyroxenites. Spinel peridotites interlayred with pyroxenites predominate below <126> 20 km. The seismic Moho is located within the layered pile.

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019069   Biswas S K (NO, , 6 Sidhartha Enclave, Gen Mahadev Singh Road, Ballupur, Dehra Dun-248 001) : Evolution of rifts basins in India during gondwana with special reference to western Indian basins and their hydrocarbon prospects. Proc Indian Natn Sci Acad-Pt A 1999, 65(3), 262-83.

Tectono-sedimentary evolution of Gondwana Super Group brings out several striking features. The Permian to Triassic stratigraphic sequence which constitutes the main part of the Gondwana is developed in the Eastern and Central Indian rifted basins. These basins developed in Proterozoic orgenic belts corresponding to old reactivated shear zones. The basins formed by rifting along Narmada-Son transform fault (mid-continental rift zone), NW-SE intra-continental mobile belts (Pranhita-Godavari and Son-Mahanadi grabens), Eastern Ghat orogenic belt between India and Antarctica (East Coast rift zone) and N-S basin margin of Bengal (Purnea-Rajmahal-Galsi rift). Two opposing views on the evolution of Indian Gondwana basins - (a) sediments were deposited originally in extensive basins and preserved in large grabens following extensive erosioin during Late Mesozoic-Cenozoic and (b) sediments are syn-rift deposits in rifted basins, have been discussed in the light of the present concepts of rift basin development. It is concluded that the Gondwana sediments were deposited during major rift cycle as syn-rift fills as advocated by the proponents of the second view. The Lower Gondwana sediments (Talchir-Barakar sequence) were deposited in initial sag basins, the so called "Master Basin", over the rift sites along ancient shear zones during pre-break up distention phase of Gondwanaland. Later sequences were deposited in the evolving rift basins as syn-rift fills.

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018222   Yerneni S;Bhardwaj D;Phadke S (Centre for Development of Advanced Computing, Pune University Campus, Pune-411 007) : Parallel implementation of wave equation based imaging technique on PARAM 10000. J Indian Geophys Union 1999, 3(1), 45-50.

Wave equation base imaging gives better picture of subsurface. It preserves amplitude information of the data. But it is highly compute intensive. Natural divisibility into smaller task and localized communication pattern in this method give strong motivation towards its performance on parallel machines. Parallel implementation of the algorithms on a parallel computer (PARAM 10000) is discussed. Maximum degree of parallelism, efficiency and speed is achieved by reformulating the problem and proper restructuring of the computer program.

018221   Walter Ritter;Pedro Mosino;Enrique Buendia (NO, Centro de Ciencias de Atmosfera, Circuito Exterior, CV, 04510, Mexico, DF, Mexico) : Dynamic rain model for linear stochastic environments. Mausam 1998, 49(1), 127-34.

To develop modern agriclture, a vision of an integral management is required, where the complexity of interactions between climatic, biological, economical, social and political factors involved in the food production must systematically be analyzed in a context of regional conditions. Statistical model is used to accomplish the objectives above mentioned. The rainfall variability in several areas of the Tlaxcala State (Mexico) is analysed with due regard to both inter- and intra-annual relations, considering that the cumulative rainfall, in the former case, follows a logistic curve and in the latter it follows a linear, first order, stochastic process.

018220   Wakdikar M P;Deo M C (Dept. of Ocean Development, Govt. of India, New Delhi-110 003) : Dynamic vector simulation and forecasting of monthly flows. ISH J Hydraul Engng 1999, 5(2), 31-43.

Planning of water resources can be conveniently made if forecasts of all monthly streamflows in a following year are made available to planners at the beginning of a rain year. Proposes a dynamic vector model to enable this. It is based on the Kalman Filter approach of forecasting. It takes into account the measurement as well as modelling errors, caters to the lag values as high as 23 months and also obviates the need to precisely specify the initial parameters. Analysis of different sets of monthly flow data indicated that the model satisfactorily simulates and forecasts 12-monthly streamflow values for a subsequent year. The model parameters are found to undergo steady convergence during their recursive estimation.

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018219   Wadhwa R S;Ghosh N;Chaudhari M S;Rao C S; Chandrashekhar V (Central Water and Power Research Station, , Pune-411 024) : Integrated geophysical investigations for atomic power project at Tarapur, Maharashtra. J Indian Geophys Union 1999, 3(1), 25-35.

Generating capacity of the existing Atomic Power Station at Tarapur is proposed to be increased by setting up two new reactors. To design the civil structures efficiently and to account for the vibratory effect of `design-basis-earthquake', the subsurface geology is required. Geophysical surveys comprising seismic refraction survey, electrical resistivity soundings and cross-hole seismic testing were carried out to obtain bedrock quality, resistivity distribution and variation of dynamic elastic moduli of rocks with depth. The surface seismic and electrical methods reveal that the depth to bedrock varies from 2.0 to 15.0 m. The compressional and shear wave velocities in the area range from 4500 to 60000 m/sec and 2900 to 3250 m/sec respectively. The dynamic Young's and shear moduli of elasticity upto a depth of 51 m vary from 6.19 - 7.19 X 10⁵ Kg/cm² and 2.90 - 2.93 X 10⁵ Kg/cm² respectively, indicating that the basaltic rock is of good quality. No weak zones requiring foundation treatment were deciphered within a depth of 51 m. The apparent resistivity contours for the switch yard area reveal that the resitivity values are the lowest for an electrode separation of 5 m corresponding to a depth of about 2 m, suggesting this as a suitable depth for earthing purpose.

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018218   Viswanadham D V;Satyanarayana A N V (Department of Geophysics, Banaras Hindu University, , Varanasi-221 005) : Atmospheric surface layer fluxes over a semi moist tropical monsoon station. J Indian Geophys Union 1999, 3(1), 15-23.

Varanasi (25° 18', 83° E), a semi moist regime, is chosen for studying the surface layer fluxes of momentum and sensible heat. The variation of these fluxes with stability has been studied. An attempt has been made to relate the sensible heat flux with monsoon rainfall. The flux-profile relationships over Varanasi has been studied in the light of M-O similarity theory. The slow response (1 Hz) and the fast response data (<126> 8 Hz) data of MONTBLEX-90 have been made use of for the present study.

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018217   Venkatesh B;Singh R D (NO, NIH Hanuman Nagar, Belgaum) : Development of regional flood formula for Krishna basin. ISH J Hydraul Engng 1999, 5(2), 44-54.

Aims at developing regional flood formulae for the Krishna basin covering the parts of Karnataka and Maharashtra states. The study has been carried out using Index-flood, EV-I, GEV and Wakeby distributions. The results indicates that Index-flood method and EV-I distribution yields better results in comparison with the other two methods used in predicting the flood at different sites in the basin.

018216   Thomas A;Sharma P K;Sharma M;Sood A (NO, Punjab Remote Sensing Centre, Ludhiana-141 004) : Hydrogeomorphologica mapping in assessing ground water by using Remote Sensing Data - a case study in Lehra Gaga block, Sangrur district, Punjab. J Indian Soc Remote Sens 1999, 27(1), 31-42.

Hydrogeomorphological mapping IRS-IB LISS II data and evaluation of ground water prospects of each hydrogeomophological unit in the Lehra Gaga block of Sangrur district, Punjab have been studied. The major geomorphic units identified in the area are, alluvial plain, sand dunes, palaeo channels and the Ghagar flood plain. The study area being part of alluvial plain has good to excellent ground water prospects. Field observations showed that ground water occurs under both confined and unconfined conditions with water table at shallow depth. The area on either side of the Ghagar river and along the major canals (about 46% of the total geographical area in the block) have good quality of ground water and is suitable for irrgation, whereas the water quality is marginal (sodic) in 52 per cent of the block.

018215   Suresh R;Sivagnanam N;Suresh Chandra K (NO, Regional Meteorogical Centre, Chennai-600 006) : Prediction of weather parameters on a very short time scale by an auto regressive process for aviation flight planning. Proc Indian Acad Sci-Earth Planet Sci 1999, 108(4), 277-86.

Forecasting weather parameters such as temperature and pressure with a reasonable degree of accuracy three hours ahead of the scheduled departure of an aircraft helps economic and efficient planning of aircraft operations. However, these two parameters exhibit a high degree of persistency and have non-stationary mean and variance at sub-periods (i.e. at 0000, 0300, 0600, ..., 2100UTC). Hence these series have been standardised (to have mean 0 and variance 1) and thereafter seasonal differenced (lag 8) to achieve almost near stationarity. An attempt has been made to fit the standardised and seasonal differenced series of Chennai (a coastal station) and Trichy (an inland station) airport into an Auto Regressive (AR) process. The model coefficients have been estimated based on adaptive filter algorithm which uses the method of convergence by the steepest descent. The models were tested with an independent data set and diagnostic checks were made on the residual error series. An independent estimation of fractal dimension has also been made in this study to conform the number parameters used in the AR processes. The models contemplated in this study are parsimonious and can be used to forecast surface temperature and pressure.

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018214   Srivastava H N;Sinha Ray K C (NO, India Meterological Department, New Delhi-110 003) : Chaotic dynamics in Parkfield region, California and characteristics earthquakes. Mausam 1999, 50(1), 99-104.

Based an about 75000 earthquakes in the California region detected through parkfield network during the years 1969-1987, the occurrence of chaos was examined by two different approaches, namely, strange attractor dimension and the Lyapunov exponent. The strange attractor dimension was found as 6.3 in this region suggesting atleast 7 parameters for earthquake predictability. Small positive Lyapunov exponent of 0.45 provided further evidence for deterministic chaos in the region which showed strong dependence on the initial conditions. Implications of chaotic dynamics on characteristic Parkfield earthquake has been discussed . The strange attractor dimension in the region could be representative for the Transform type of plate boundary which is lower than that reported for continent collision type of plate bounday near Hindukush northwest Himalayan region.

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018213   Srinivas S;Moharir P S;Maru V M (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Bernstein preprocessing for nonlinear least squares inversion of gravity and magnetic data. Proc Indian Acad Sci-Earth Planet Sci 1999, 108(4), 269-75.

Nonlinear, nonlocal and adaptive optimization, now readily available, as applied to parameter estimation problems, require that the data to be inverted should not be very noisy. If they are so, the algorithm tends to fit them, rather than smoothening the noise component out. Here, use of Bernstein polynomials is proposed to prefilter noise out, before inversion with the help of a sophisticated optimization algorithm. Their properties are described. Inversion of gravity and magnetic data for basement depth estimation, singly and jointly, and without and after Bernstein-preprocessing is conducted to illustrate that the inversion of Bernstein-preprocessed gravity data alone may be slightly superior to the joint inversion of gravity and magnetic data.

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018212   Sinha S K;Narkhedkar S G;Rajamani S (NO, Indian Institute of Tropical Meteorology, Pashan Road, Pune-411 008) : Application of Sasaki's numerical variational technique to the analysis of height and wind fields over Indian region. Mausam 1998, 49(1), 1-10.

Objective analysis method based on Sasakis numerical variational analysis technique has been taken up for the analysis of geopotential height and wind over the Indian region. The univariate optimum interpolation (UOI) method is used to generate the initial or input fields. These fields are then adjusted by the variational method. A study of this method over Indian and adjoining region for 850, 700, 500, 300 and 200 hps levels is made from 4 to 8 July 1979 and the analyses obtained using this method are compared with the PGGE analyses.

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018211   Singh S D (Palaeontology Laboratory, KDM Institute of Petroleum Exploration, Oil and Natural Gas Corporatio, Kaulagarh Road, Dehra Dun-248 195) : Petrography and clay mineralogy of intertrapean beds of Mumbai, India. J Geol Soc India 2000, 55(3), 275-88.

Petrographic attributes of intertrappean beds exposed at four localities in Mumbai, one each at Malabar and Worli Hills and two at the Amboli Quarry, Jogeshwari are studied. Microfacies of vitric tuff, lithic tuff and black carbonaceous shale have been identified, which differ from their counterparts in other intertrappean localities of peninsular India in having a significant amount of pyroclastics. Bulk XRD analyses of intertrappean beds of Malabar Hill show similar mineral assemblage in tuffs as well as black carbonaceous shales pointing towards the same provenance for these beds. Further, the XRD analysis of the clay fraction of these samples reaffirms their pyroclastic nature, the pyroclasts being reworked in most cases.

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018210   Singh K V (India Meteorological Department, , New Delhi-110 003) : Karaikal cyclonic storm of November 1991 : a case of marginal severe cyclone. Mausam 1998, 49(1), 148-50.

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018209   Singh G P (Directorate of Geology and Mining, U P Regional Office, Jhansi-284 001) : Delineation of geology of a part of Bundelkhand complex around Girar, distt. Lalitpur, U.P., using remote sensing data. J Indian Soc Remote Sens 1999, 27(1), 1-8.

Attempt is made to mark regional geology of part of Lalitpur district. The area is characterized by flat topography gently sloping east ward with isolated hillocks. The well contrasted lithology has been marked on the basis of variation in tone, drainage pattern and texture. The main lithounits are foliated granites/gnesis, banded iron formation, granites, ultra basic, quartz reef and basic dykes. The structural elements of lineaments are visible on aerial photos and imagery which range in length from 1 to 10 km. The lineaments at places intersect with each other. The major trends are NNW-SSE, NE-SW, NNE-SSW. These NNW-SSE and NE-SW lineaments are reflected by well aligned body of quartz-sericite schist and quartz reef respectively.

018208   Shyamala E;Shinde G M (NO, Area Cyclone Warning Centre, Colaba, Mumbai) : Study of synoptic systems associated with intraseasonal variability of summer monsoon. Mausam 1999, 50(1), 31-6.

An attempt has been made to identify the important synoptic situations that result in widespread rainfall activity in Maharashtra and Gujarat based on latest observational technology and develop forecasting techniques for day to day short range prediction of monsoon activity in these areas with special reference to monsoon'96.

018207   Shravan Kumar;Thakur Prasad;Agrawal A L (NO, Regional Meteorological Centre, Colaba, Mumbai-400 005) : Synoptic-climatic study of the onset of southwest monsoon over Mumbai. Proc Indian Acad Sci-Earth Planet Sci 1999, 108(4), 321-6.

Surface and upper air synoptic features prevailing at the time of onset of southwest monsoon over Mumbai have been examined for a period of 50 years from 1947 to 1996. These synoptic situations have been found to fall under three broad categories. The study shows that on about 66% of the occasions, the onset of monsoon over Mumbai is caused by low pressure area forming over southwest and east central Arabian Sea as they move northwards, while on 28% of the occasions, the onset is due to the low presure systems forming over northwest/head Bay of Bengal and their movement towards northwest/west northwest. Based on the findings of the study and the climatological aspects, a criterion for declaring onset over Mumbai has been suggested.

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018206   Shekh A M;Kulshreshtha M S;Patel H R;Parmar R S (Department of Agricultural Meteorology, Gujarat Agricultural University, Anand) : Relationship of mean temperatures with screen temperature. Mausam 1998, 49(1), 21-6.

Attempt has been made to study the variation in daily mean temperatures obtained from maximum and minimum temperatures and that obtained from hourly temperatures by the automatic weather station at the Agrometeorological Observatory, Anand (Gujarat). The mean temperatures obtained from the records of daily maximum and minimum temperatures were higher and fluctuated from -1.5 to 1.5°C during the months of September to May as compared to the respective values obtained from hourly temperature recorded by the automatic weather station. However, during May to September, these daily mean temperatures were found to be higher than mean temperatures obtained from the automatic weather station. Different coefficients were deduced from the records of the automatic weather station to estimate the hourly temperatures and a model was developed similar to that of Willam Logan (1981). The hourly temperatures and the dialy mean temperatures so estimated were in good agreement with the respective actual hourly and daily temperatures record by the automatic weather station. Therefore, by using this model one could estimate the true daily mean temperature from the records of maximum and minimum temperatures.

018205   Sarmah S K (NO, , Arya Nagar, College Road, Guwahati-781 016) : Probability of occurrence of a high magnitude earthquake in Northeast India. J Geophys 1999, 20(3), 129-35.

North east India is one of the seismically active regions of the world. Two very high magnitude earthquakes occurred in this region in 1897 (M=8.7) and 1950 (M=8.7) during last one hundred years. History of the region indicates occurrence of destructive earthquakes at the interval of about 50 years. Application of b-value and Gumbel's statistical methods to the earthquakes recorded in the region during 1897-1992, indicate an average return period of 55 years for earthquakes of magnitude 8 or greater. The last big earthquake of magnitude 8.7 occurred in 1950. So, statistically, the region is ready for an earthquake of similar magnitude. Diminution of the number of high magnitude earthquakes since 1960, diminution of ts/tp, ratio with time and accumulation of strain in the region tend to indicate the probability of occurrence of a high magnitude earthquake in the region in the near future.

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018204   Samui R P (NO, Indian Meteorology Department, Shivajinagar, Pune-411 005) : Weather and rice yield relationship at some stations in India. Proc Indian Acad Sci-Earth Planet Sci 1999, 108(4), 309-16.

Study has been conducted with four traditional photosensitive and one high yielding rice varieties grown during the kharif season under rainfed conditions. The curvilinear technique was used to examine the influence of meteorological parameters on the yield of rice. Rice varieties grown in different agroclimatic regions performed differently to climatic parameters. The maximum yield was observed when rainfall ranged between 100 and 115 cm. Maximum and minimum temperature range of 29-32°C and 23-25°C respectively appear ideal for optimum yield. Photoinsensitive high yielding variety performed well even at low light intensity (250-350 hours of bright sunshine).

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018203   Saini K M;Deb T K;Mitra P P;Ghatol S G;Sen A ;Saha N C;Das S N (NO, All Insia Soil and Land Use Survey, New Delhi) : Assessment of degraded lands of Puruliya district, West bengal using remotely Sensed Data. J Indian Soc Remote Sens 1999, 27(1), 23-30.

Land degradation in Puruliya district, West bengal was assessed using remote sensing techniques. Analysis of satellite data (False Colour Composite in 1:50,000 scale) was carried out visually and subsequent ground verification and translation of imagae interpretation units into various categories of degraded lands. Results indicate that 31.8 per cent area of the district suffers from one or the other kind of land degradation. Water induced soil erosion is the major problem which accounts for 31.3 per cent area of the district. Land degradation due to waterlogging is limited to only 0.3 percent area whereas 0.2 percent area is degraded due to rock quarries, brick kiln and industrial effluents. The open scrub land are most vulnerable to soil erosion with 15.45 per cent area affected followed by agricltura lands with 12.35 per cent area degraded. Forest lands are least affected with 4.0 per cent area under degradation. The results also indicate that land degradation is quite significant in undulating plain and plateau lands accounting for 16.05 and 13.35 per cent are respectively. The land degradation problem is not so serious in hilly region, where only 2.4 per cent area is affected by water erosion.

018202   Saha K R;Dool H M V D;Saha S (NO, , 27, B-Road, Maharani Bagh, New Delhi-110 065) : View of global monsoons in observed and model climatology. Mausam 1998, 49(1), 79-94.

17year (1979-95) mean January and July climatology obtained from a T 62/28 - level version of the National Centres for Environmental Prediction (NCEP) global spectral operational model is compared with a mean observed climatology for the same period obtained from its reanalysis project, with a view to finding out how well it captures some of the well-known characteristics of the global monsoon circulation generated seasonally by differential heating of the earth's surface by the sun in the course of its annual oscillation about the equator. Good correspondence between the two is found in the fields of mean monthly anomaly (deviation of monthly mean from the annual mean) of surface temperature, surface pressure, atmospharic circulation and total rainfall over most parts of the global, barring a few exceptions mostly in circulation and rainfall. Large diversity in the distribution and intensity of monsoon found over different region due to land-sea configurations, cold and warm ocean surfaces and high mountain ranges appears to be well reflected in model and observed climatology. However, the concept of a single equatorial trough moving from one hemisphere to the other to cause advance and onset of monsoon appears to fail especially over warm oceans, where there appears to be evidence in favour of two troughs, one in each hemisphere. It is the equatorial trough in the summer hemisphere that oves to bring up the mosoon in that hemisphere.

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018201   Roy Bhowmik S K;Mishra P K (NO, Meteorological Centre, Bhubaneswar) : Some structural characteristics of pre-monsoon depression in the Bay of Bengal. Mausam 1999, 50(1), 19-24.

During the period 6 to 16 May, 1995, three deep depressions formed one after another over west bay of Bengal and moved from south to north. Structural characteristics of these systems are investigated from the distribution of thermal and thermodynamical field observed around the depression center utilising Rs/Rw and other available coastal observations during the period. Major findings of the study are the depressions have low cold core and middle and upper tropospheric warm core; thermal and moisture fields tilt north ward with height but vertical tilt of contour height is not uniform at all levels; during intensification of the system significant increase in temperature and moisutre occurs above 700hPa and significant fall of contour height occurs below 300hPa.

018200   Roy Bhowmik S K (NO, Meteorological Centre, Bhubaneswar) : Some dynamical aspects of meso-scale rainfall events as revealed by physical initialization. Mausam 1998, 49(1), 11-20.

In recent years, physical initialization has emerged as a powerful tool to improve initial state of dynamical model during assimilation phase. This improved initial state at high resolution global spectral model is able to provide a tropical meso-scale coverage. Model is used to study some dynamical aspects of meso-scale rainfall events. Major findings of this study are : Meso-scale rainfall events carries a distinct dynamic structure in vertical profles of divergence and vertical upward motion, Meso-scale events exhibits a large diurnal variation in these vertical profiles and Vertical motion field of meso-scale organisation appears to play a significant role in tropical storm formation.

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018199   Rase D M (NO, Meteorological office, Pune-411 005) : Fluctuations, trends and periodicities rainfall over central India. Mausam 1998, 49(1), 144-8.

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018198   Rao K P R V;Satyanarayana K V;Srinivas S; Acharya R S (Geological Survey of India, , Hyderabad) : Exploration for gold in a resistive environment - a case study from Dona (east), Jonnagiri Schist Belt, Andhra Pradesh. J Geophys 1999, 20(3), 95-102.

Induced polarisation methods are generally successful in identifying sulphide associated auriferous zones when the host rock and the surrounding rock units have a good contrast in conductivity. Since I P phenomenon is bassically related to electrochemical activity, I P effect are dependent on the porosity of the rock units besides the two types of conduction. In (Dona) (east) blcok gold mineralisation is associated with highly sheared, altered granodiorite traversed by quartz veins with sparse sulphide disseminations. As the country rock granodiorite and the host rock are `resistive' reducing the porosity considerably, the I P signals are poor. However, the alternations associated with the sheared host rock enabled its delineation recording high resistivities. The sulphide rich zones are reflected as chargeability `highs'. The S P response, though feeble, probably related to fractured zones. A few borehole sections alongwith geophysical profiles are discussed to exemplify the above geological situation.