014917   Murthy K S R;Venkateswara Rao V (Centre for Remote Sensing, Department of Geo-Engineering, College of Engineering, Andhra University, Visakhapatnam-530 003) : Mapping of hydrogeomorphological features in Varaha river basin using IRS data. J Indian Soc Remote Sens 1999, 27(2), 71-9.

Hydrogeomorphological mapping in Varaha River Basin (VRB) was carried out to develop relationship between groundwater condition and geomorphology of the area. The VRB is located in the north coastal region of Andhra Pradesh is characterised by variability in precipitation, temperature, vegetation, infiltration and run-off. Realising the significance of remote sensing in natural resource management and development. IRS IA data was used in the study. It is inferred that various hydrogeomorphological units identified in the study area, are the outcome of different geomorphic processes that have been operating in the area and reveal which close relationship between groundwater condition and geology and geomorphology of the area. Areas covered by buried channels have shallow aquifers of good quality water with excellent yield. Lineaments and fractures may prove to be potential zones for ground-water development.

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014916   Mukherjee S (School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067) : Microzonation of seismic and landslide prone areas for alternate highway alignment in a part of Western coast of India using remote sensing techniques. J Indian Soc Remote Sens 1999, 27(2), 81-90.

West coast of India is a narrow and linear, a portion from Bombay to Goa is this track is known as Konkan coast. Remotely Sensed geocoded data from IRS-1B has the potentiality in identification of localized patches of change in environmental parameters, which includes changes in lineament pattern, vegetation anomaly, rock debris and occurrence of landslides. Ground protuberances in this terrain are important surface manifestations of probable seismic activity. In these areas quaquaversal drainage pattern is inferred. Landslides are also expected in places near NH-17 (National Highway - 17) which may affect the socio-economic scenario of area. Alternate highway alignment is planned based on least hazard potentiality of the terrain. Weathered Basalts inferred, near the bank of Amba river, were not recommended for tunnel construction. Anomalous clay patches need more care for road construction. Inferred joints, fractures and faults were found in some places which were marked as hazardous locations. Some areas were marked hazardous for road construction due to the presence of palaeochannels but the same were marked as potential areas for ground water exploration.

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014915   Mukherjee M M (NO, Geological Survey of India, Bhubaneswar) : Gold mineralisation in banded iron formation of India. SGAT Bull 2000, 2(1), 65-70.

BIF-hosted gold deposits and ostensible auriferous nature of many BIF horizons occurring at various stratigraphic levels in Archaean to Proterozoic volcanosedimentary structural belts are known widely from most of the shield areas of the world. Many such occurrences have been reported from Dharwar granite greenstone (Archaean) terrain of South India and similar auriferous BIFs have come to light from Central and Eastern India cratonic areas as well. A 3-fold classification of BIF-hosted gold deposits has been proposed based on the well established Dharwarian lithostratigraphy. The most important one is the Homestake-type" which occurs in the upper part of Chitradurga Group, the youngest unit of Dharwar Supergroup. Banded magnetite quartzite with sulphide and carbonate along with structurally- controlled gold ore bodies characterise this type. Next in importance is the gold mineralisation hosted by "Algoma-type" BIFs associated with submarine volcanic rocks which are often bimodal in nature. "Algoma-type" BIFs occur in: high grade Sargur Group predating the Peninsular gneiss (3000 m.y.); Sulphide facies BIFs occurring within submarine volcanic formations in the middle part of Chitradurga Group; Silicate-sulphide facies BIFs of the Eastern Greenstone Belts of Dharwar. Gold mineralisation in this type are both syngenetic and epigenetic in nature. The third and the least important type is "Superior-type" BIF which occurs in the Bababudan Group.....

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014914   Mishra R N (NO, Geological Survey of India, Calcutta-700 016) : Concept of metallogensis as applied to the Indian mineralization scenario. SGAT Bull 2000, 2(1), 31-46.

Overview of crustal evolution of the earth has brought out important geological time slots when remarkable have been noticed, e.g., the characteristic blank of the first billion years, the total absence of free plutonic quartz thereafter till 2.8. b.y. and the subsequent change over between 2.8 b.y. to 2.4 b.y. from a completely pristine simatic crust to a sialic crust of the present day. Global tectonics, plutonism, basin formation changed the complexion of crust with time. Mineral formation and metallogenesis went in simultaneously associated in space and time with these forces and their products. The idea of sapce and time confines in metallogenesis, brought in the concept of metallogenetic provinces and metallogenetic epachs. Analysis of metallogenesis in the Indian geological milieu encompasing 3.3 million sq.km area together with 200 km vide exclusive economic zone (EEZ) in to the sea have resulted in several important metallogenetic macrozones and metallogenetic epochs. Altogether eight metallogenetic macrozones (Himalayan orthogeosyncline, Indogangetic foredeep, platformal blocks, epiplatformal orogenic belts, cratonic zones of autonomous-tectono-magmatic-activisation, proto continental nuclear masses on land and continental snelf and continental slope in the marine sector) and nine metallogenetic epochs (3000-3200, 2000-2400, 1100-1500, 600-900, 200-400, 60-100, 15-50, 1-10 and present to I million years BP) have been identified and discussed.

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014913   Minakshi Chaurasia R;Sharma P K (NO, Punjab Remote Sensing Centre, PAU Campus,, Ludhiana-141 004) : Landuse/land cover mapping and change detection using satellite data - a case study of Dehlon block, district Ludhiana, Punjab. J Indian Soc Remote Sens 1999, 27(2), 115-21.

Land use information collected for Dehlon block of Ludhiana district, Punjab from the analysis of the IRS-1B LISS-II data for the year 1993 and IRS PAN data for the year 1997 and SOI topographical maps for 1964 revealed a large change in the area of different land use categories during the period from 1964 to 1997. The agricultural land covering an area of about 94.14 per cent in 1964 reduced to 90.26 per cent in 1997, while the area under rural settlements increased from 312 ha in 1964 to 1162 ha in 1997. An extra area of about 169 ha under waste land was added during the period under study making total waste land area to about 400 ha in 1997. However, the block lacks the forest cover of the required limit. Considerable change in living environment was observed in the block. Number of persons per unit settlement area (ha) being 213.3 in 1964 reduced to 97.1 in 1991; it indicate that the living standard of the people of the block has improved with the changed cropping pattern and increased agricultural production during the period from 1964 to 1991.

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014912   Mallan G V (NO, Meteorological Office, Pune-411 005) : Application of marine climatology. Vayu Mandal 1997, 27(3-4), 43-6.

Very major part of the global surface is covered with the oceans. Hence, the climatology over the oceans is of utmost importance to any marine operation. The importance of systematic collection, compilation and publication of summaries of the Meteorological data recorded over the oceans of the globe was recognised by W.M.O. vide Res. 35 at its IV congress. It formulated a scheme of allocating the ocean area to eight responsible memebers to undertake this task. Under Indian area of responsibility is the Indian Ocean North of 15° S between 20° E and 100° E. All surface Meteorological observations recorded by voluntary observing ships of all Nations in this area of responsibility are expected to be collected, archived and processed by India. The processed statistics are published in the form of Marine climatological summaries. These are used for a number of applications such as design of marine structures and ocean transportation. Fisheries, recreation and many other ocean-based activities use the same data and share many of the same techniques in the development of analysed products. The importance of marine climatic elements and their relative importance of marine operations and the design structures are discussed.

014911   Kulkarni B D (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Probable maximum precipitation over Plain areas of Maharashtra - a generalized approach. Vayu Mandal 1997, 27(3-4), 20-5.

Estimates areal probable maximum precipitation (PMP) for 1000, 5000 and 10,000 km² for 1-day duration over Maharashtra, three generalized charts depicting variation of areal PMP for these areas have been prepared. The study showed that the areal PMP estimates for 1000, 5000 and 10,000 km² over Maharashtra-seem to vary from 70-25, 60-20 and 45-20 cm. respectively for 1-day duration.

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014910   Kalyanaraman S (NO, ISRO Satellite Centre, Bangalore-560 017) : Remote sensing data from IRS satellites - past, present and the future. J Indian Soc Remote Sens 1999, 27(2), 59-69.

Under Indian Remote Sensing Satellite Programme, so far seven satellites have been launched to provide land, water, agricultural and Oceanographic information for resources monitoring and management under National Natural Resources Management System. The continuity of the data services is planned by way of providing improved multi-spectral data, panchromatic data and oceanographic/atmospheric data, in the future also. The various errors in the satellite data namely radiometric and geometric errors which are to be corrected on ground before the data is put for use have been explained. The characteristics of the future satellites are also described.

014909   Jaiswal R K;Saxena R;Mukherjee S (NNRMS, ISRO, Headquarters, Dept. of Space, , Antariksh Bhavan, New BEL Road, Bangalore-560 094) : Application of remote sensing technology for land use/land cover change analysis. J Indian Soc Remote Sens 1999, 27(2), 123-8.

Land use/land cover changes over a period of 30 years were studied using remote sensing technology in a part of Gohparu block, Shahdol district of Madhya Pradesh. Land use/land cover maps were prepared by visual interpretation of two period remotely sensed data. Post-classification comparison technique was adopted for this purpose. The loss of vegetation cover was estimated to be 22 percent and 14 percent of the land was found to have been tranformed into wasteland between 1967 and 1996. Overall rate of change was found to be 1.8 percent per year during this period.

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014908   Islam Z;Salehin M (NO, Institute of Flood Control and Drainage Research (IFCDR), Bangladesh U, Dhaka-1000, Bangladesh) : Experimental study on floodplain sedimentation due to piping in the river embankment. Indian J Pwr River Valley Dev 1998, 48(9-10), 144-154.

Describes the results of the experiments conducted in a distorted model at IFCDR, BUET in 1994-97 to observe the sediment deposition processes over the floodplain vegetated with rice plants due to different piping diameters of 2 cm, 4 cm and 6 cm and piping depths of 2 cm, 4 cm and 6 cm in the river embankments. The model was made of reinforced cement concrete with the working section of 300 cm in lengt hand 112.5 cm in width including a floodplain, a river channel and an embankment with required diameters and depths of piping. During model runs average velocity, discharge and sediment concentration in the river channel were 29.6 cm/s, 4002 cm³/s and 8126 gm/l respectively. In each model run 23 kg of sediments with median diameter (d50) of 0.10 mm (100 micron) were used in the river channel. Each model run was conducted for the elapsed time of 30 minutes. Upon the completion of the model run measurements of sediment deposition thicknesses were made at 2-cm interval over the floodplain with the help of a movable point gauge fixed on two aluminum rails. The results of the model experiments showed that the total maximum and mean thicknesses and total volume of sediment deposition over the floodplain increased with the increase of diameters and depths of piping in the embankments.

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014907   Haldar A L;Rao L I M (NO, Remote Sensing Applications Centre, Lucknow-226 021) : New approach for delineation of potential aquifer by remote sensing and geophysical technique at Muhammadabad, Jalaun district, Uttar Pradesh. J Indian Wat Wks Ass 1999, 31(4), 243-8.

Highly favourable zones for accumulation of ground-water have been selected utilising the remote sensing data at Muhammadabad, Jalaun district, U.P. Vertical Electrical Soundings (V.E.S.) with Schlumberger array have been conducted at selected points based on remote sensing data. The layer parameters obtained by interpreting the field curve with the help of indirect method, were fed to inverse filter based Koefoed's (1997) computer programs for finding the discrepancy between field curve and computed one and thus the actual layer parameters are evaluated. Lithologs were collected and observations were noted at drilled site. At the same instant geophysical logging comprising self-potential, short and long normal resistivity, single point resistance and natural gamma ray were also conducted. Based on the interpretation of well logs thickness of potential zone is evaluated. These results are further compared with VES parameters and lithology.

014906   Dhanna Singh;Bhadram C V V;Mandal G S (NO, , 248, Aravali Apartment, Alaknanda, New Delhi-110 019) : Intensity of heat low during May and interannual variability of Indian summer monsoon rainfall. Vayu Mandal 1997, 27(3-4), 26-30.

Analysis of 46 years (1948-1993) data has revealed that the average lowest MSL pressure of heat low over central Pakistan and adjoining northwest India for the month of May (P5) has the potential as a parameter for predicting summer monsoon seasonal rainfall for the entire country as a whole and for contiguous area of all meteorological sub-divisions along the mean position of monsoon trough. P5 has more significant correlations with 0.1% to 5% level of significance with seasonal rainfall of all the sub-divisions around that monsoon trough region. In comparison with other circulation parameters, analysed in this study, the new parameter P5 has greater potential to foresee the monsoon seasonal rainfall of the contiguous sub-divisions along the monsoon trough region. Considering P5 and other circulation parameters multiple regression have been developed and tested for seasonal rainfall of monsoon trough region.

014905   De U S;Shewale M P;Sen A K (NO, Meteorological Office, Pune-411 005) : Role of India meteorological department in agrometeorological activities. Vayu Mandal 1997, 27(3-4), 7-12.

India has heterogeneous climate and the climatic diversity itself calls for a detailed and in depth analysis of the types of crops grown in different climate zones vis-a-vis the impact of probable climatic change. To study agrometerology and to carry out experiments on physical environment related to crop growth, a Division of Agricultural Meteorology was established in India Meteorological Department (IMD) at Pune in 1932. Review of the agrometeorological activities in India and WMO's support for the same is given.

014904   Das S (NO, Central Ground Water Board, Bhubaneswar) : Aquifer properties and productivity in fissured and porous formations in Orissa. SGAT Bull 2000, 2(1), 1-12.

State of Orissa presents unique hydrogeological complexity with the major parts of the terrain underlain by hard crystalline rocks, Gondwanas, Tertairies and the rest by coastal alluvium. Discontinuity in aquifer distribution and inhomogeneity in aquifer properties and yield characterise the hard rocks. The coastal alluvium with regionally extensive, thick and high yielding aquifers present a sharp hydrogeological contrast. The yield factors and k values of aquifers range from 2.3-4.9 lpm/m/m, 0.65-42.07 m/day; 0.73-11.1 lpm/m/m, 1.5-60 m/day and 2.9-42.8 lpm/m/m, 9-330m/day in fissured basement complex, Tertiary Baripada beds and coastal alluvium respectively. Unconfined to semi-confined condition exists in weathered and fractured zones of basement complex down to 70-90m depth which mainly contributes to the well yield. In the alluvial and Tertiary terrain shallow aquifes are under unconfined condition and deeper aquifer under tremendous artesian pressure. Ground water management needs an understanding of aquifer properties and yield potentials of various hydrogeological units. An analysis of aquifer properties and productivity under varied geological and geomorphological set ups in the State.

014903   Chandra A;Kulshreshtha R;Gupta G S (Irrigation Management and Training Project, College of Technology and Agricultural Engineering (Rajasthan Agricult, Udaipur-313 001) : Modelling open pan evaporation with meteorological parameters. Indian J Pwr River Valley Dev 1998, 48(5-6), 82-4.

Various approaches based on meteorological parameters have been used to estimate evapotranspiration (ET) which may have one or more limitations when applied for climatic regions other than those for which they were originally developed. Pan evaporation data (PE) give a good index to estimate ET for agricultural crops using procedures ralating ET to PE which depends on various meteorological parameters. Hence, the necessity of developing prediction equations under a definite set of climatic conditions is of utmost need in order to decide the relative importance of meteorological parameters influencing PE. The average weekly values of meteorological parameters viz. mean air temperature, mean relative humidity, wind velocity and number of bright sunshine hours were correlated with PE through multiple linear regression analysis alongwith successive deletion of meteorological parameters found least important at a choosen level of significance. The contribution of each meteorological parameter over PE was also determined.

014902   Ashok Kumar;Tomar S;Prasad L B (NO, Bihar Council on Science and Technology, B-Block, IIIrd floor, Maurya Lok Complex, Patna-800 001) : Analysis of fractures inferred from DBTM and remotely sensed data for groundwater development in Godavari sub-watershed, Giridih, Bihar. J Indian Soc Remote Sens 1999, 27(2), 105-14.

Godavari sub-watershed is a part of buried pediplain developed over `Chotanagpur' granite gneiss. Aquifer is unconfined in nature and groundwater occurs under water table condition. In the study area, groundwater is being exploited only through dugwells which are not capable of sustaining long duration pumping. Groundwater exploration involves the investigation of depth and nature of weathered and fractured horizon. To understand the groundwater storage and retrieval in the area, the basement topography derived from Digital Basement Topography Modelling (DBTM), the lineaments identified on remotely sensed data and geohydrological and physiographic data have been analysed. From DBTM, fracture zones have also been inferred. Lineaments (probable fractures) identified with the help of remotely sensed data are linear features represented on a planner surface. Lineaments in the area are subtle in expression due to deeply buried pediplian. Correlation of lineaments with DBTM reveals that a few lineaments/fractures are deep seated and a few have no sub-surface fractures extensions. Also some sub-surface inferred from DBTM have no expressions on the image. Attempt has been made to delineate more authentic lineaments/fractures with the help of remotely sensed data and DBTM.

014901   Anil Kumar (Hill Campus, G B Pant University of Agriculture & Technology, Ranichauri, Tehri Garhwal-249 199) : Artificial recharge of groundwater through the existing irrigation well : a case study. J appl Hydrol 1999, 12(1), 30-6.

Studies were conducted on artificial recharge of groundwater under gravity-influence of a constant head build-up of 6.6 m, on an irrigation well with 7.5 cm casing internal diameter, full penetrating a confined aquifer, in Midnapur District of West Bengal. The surface runoff during monsoon season was channelized from a dug-out pond to the well. The main objective of this study was to assess the hydraulic feasibility of an irrigation well to recharge deep aquifers, and to provide some drainage relief during the periods of surpulus surface water, without incurring extra expenditure on the recharge well alone. The recharge process showed a low recharge rate with a decreasing trend with time to achieve a constant value. Equations were developed to relate the recharge rate with time for four consecutive days. It was estimated that a network of such wells with an interspacing of 200 m could provide a drainage relief of 1.8 cm per day for one hactare area.

013985   Vittal Rao K P R (NO, Geological Survey of India, Southern Region, Hyderabad) : Geophysical exploration in search of kimberlites: an appraisal from parts of Andhra Pradesh. J Geophys 1999, 20(4), 179-93.

The features of the semi-detailed maps are examined, correlating with the geological information. Prominent lineaments, either `lows' or `highs', isolated anomalies etc., are carefully sorted out and anomalous features are further tested by resistivity profiling. Exploratory pits are opened at anomalous locations to expose the bed rock. After a visual examination of the exposed rock, petrological and chemical analayses are carried-out to confirm the kimberlite affinity. Geophysical exploration in Wajrakarur kimberlite field (WKF) in Anantapur district of Andhra Pradesh was carried out for nearly 20 field seasons while geophysical work in the recently discovered Narayanpet Kimberlite field (NKF) in Mahbubnagar district of Andhra Pradesh and Gulbarga district of Karnataka was only for 3 field seasons. After such a relentless search, 3 kimberlite pipes in Wajrakarur and Lattavaram Tanda areas of Anantapur district and one in Kamusanpalli block of Mahbubnagar district were located. The review is restricted to the above 4 case studies, where the `kimberlite finds' are concealed under soil cover and one case study from Chandaraki block of Maddur-Narayanpet fielcd where the geophysical efforts are not successful in locating the kimberlite inspite of the corroborative geophysical indications. Pipe-7 from Venkatamplalli area and CG-1, CG-2 from Chigicherla area are also included to demonstrate the effectiveness of E.M. method in the former case and the close association of basic dykes in the latter.

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013984   Sudan C S;Sharma U K (P.G. Department of Geoloy, University of Jammu, Jammu-180 006) : Trace fossil distribution and stratigraphic setting of Garbyang formation in the Girthi-Ganga section of Kumaun. J Geol Soc India 2000, 55(2), 175-82.

Trace fossils from Garbyang Formation of Kumaun have been reported from two stratigraphic levels. The lower horizon F1 comprises simple traces belonging to the ichnogenera Gordia, Chondrites, Margaritichnus, Skolithos, Cochlichnus and Bergaueria. The upper F2 horizon comprises advanced type of traces of arthropod origin i.e., Monomorphichnus, Dimorphichnus, Diplichnites ad Kupwaria along with a few ichnofossils of F1 horizon. As in other Himalayan sections these trace fossil horizons are devoid of body fossils. But in Kumaun no well defined body fossils of Early Cambrian age comparable to Redlichia zone of Kashmir and Spiti have yet been reported apart from some fragmentary genal spines of trilobites. The trace fossils are important for evaluating the metazoan evolution.

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013983   Srivastava P;Shukla U K;Mishra P;Sharma M; Sharma S;Singh I B;Singhvi A K (Department of Geology, Lucknow University, Lucknow-226 007) : Luminescence chronology and facies development of Bhur sands in the interfluve region of central Ganga plain, India. Curr Sci 2000, 78(4), 498-502.

Bhur sand ridges in the upland interfluve surface are a distinctive feature of the Ganga Plain and occur as arcuate, linear and oval geomorphic highs. Their sedimentary sequences shows a few meter thick aeolian sand cover invariably underlain by fluvian channel deposits in the form of point bar succession. Infra-red stimulated luminescence (IRSL) dating of the topmost part of the channel sand and the overlying aeolian sediments yielded stratigraphically consistent results and indicated that the fluvial channel activity in the region ceased sometime during 7 to 5 ka. This was followed by a phase of deposition of aeolian sand, suggesting a phase of weakened monsoon and increased aridity.

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013982   Somayajulu B L K (NO, Physical Research Laboratory, Ahmedabad-380 009) : Growth rates of oceanic manganese nodules: implications to their genesis, palaeo-earth environment and resource potential. Curr Sci 1999, 78(3), 300-8.

Cosmic ray produced ¹⁰Be has provided the most reliable method of determining growth rates of oceanic ferromanganese nodules/encrustations of age <60> ~ 15 m.y. The uses of this parameter to understand the genesis and resource potential of these deposits and for using them as recorders of palaeo-events are briefly described.

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013981   Shrivastava J P;Salil M S;Pattanayak S K (Department of Geology, University of Delhi, Delhi-110 007) : Clay mineralogy of Ir-bearing Anjar intertrappeans, Kutch, Gujarat, India: Inferences of palaeoenvironment. J Geol Soc India 2000, 55(2), 197-206.

Clay mineral studies on the K/T boundary succession at Anjar, Kutch show smectite, sepiolite and palygorskite as its major clay mineral assemblage. There is a distinct variation in the clay mineralogy across the section with sepiolite and palygorskite dominating the lower and upper lithounits, respectively, in association with smectite. The KTB layer, marked by the Ir (1271 pg/g) and Os (1414) pg/g) anomaly contain sepiolite and smectite in subequal proportions. The clay stratigraphy of the succession reflects progressive increase in aridity and basicity in the depositional environment during the deposition of Anjar KTB sediments. It appears that the sepiolite-palygorskite-smectite complexes in the sediments were developed in a lacustrine or peri-marine environment of high basicity under arid conditions induced and influenced by Deccan volcanism. In this environment, the Si, Mg and Al ions necessary for the formation of sepiolite and palygorskite could be supplied by the hydrothermal fluids associated with volcanism by the dissociation of silicates already available in the depositional environment or simultaneously by both the processes. Clay mineral associations in the Ir-bearing Anjar intertrappean sediments across its lithounits are more compatible with the depositional environment influenced by the volcanism, than an asteroidal impact. In the upper part of the succession, the predominance of palygorskite and smectite suggests that the latter contributed the necessary Al, Si and Mg ions to result the former. The REE signatures indicate that sepiolite-smectite is most likely te carrier phase of Ir in Anjar intertrappeans.

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013980   Sharma U P;Tripathi B K;Rai A K (Atomic Minerals Division, , Nagarbhavi, Bangalore-560 072) : Petrochemical characterisation of Tin-bearing pegmatites of Paharsingh area, Ranchi, Bihar. Indian J Geochem 1998, 13, 33-50.

Tin bearing pegmatites of Paharsingh area are mostly emplaced concordantly along the calc silicates and adjoining rocks of Proterozoic folded metasedimentary sequence of Chhotanagpur Granite Gneiss Complex (CGGC). These pegmatites have been categorised into two groups i.e. group I (schorlites) and Group II (tourmaline pegmatites and tourmaline bearing granitoidal pegmatites). The pegmatites are mainly lenticular vein and occasionally pod-type which contain cassiterite in a very small amounts with Sn ranging from 18-98 ppm in group II, while 224-487 ppm in group-I pegmatites with at places as high as 0.23% as cassiterite lumps. Some of the small pegmatites also occur in the basic granulites and biotite gneisses but are mostly unproductive and barren (Sharma, 1986). These tin-bearing pegmatites (fertile), in contrast to barren ones, are depleted in CaO, Sr, Ba, Zr and enriched in K₂O, Na₂O, Li, Nb, F with characteristically higher ratios of K₂O/Na₂O, Rb/Sr, F/Li, Ba/Sr and lower ratios of K/Rb, Ba/Rb, Mg/Li. These data show correspondingly increase of incompatible and large ion lilthophile elements (LILE) and decrease of compatible and small ion lithophile elements except Be and Li with respect to Sn. The study reveals that the pegmatitic generated by partial melting of the metasediments and older granite gneisses of CGGC followed by fractionation and are compared well with S type of granitoids.

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013979   Sharma K P;Maswood M (Department of Geological Sciences, Gauhati University, Guwahati-781 014) : Structure controlled mode of emplacement of pegmatite around Guwahati, Kamrup district, Assam. Indian J Geochem 1998, 13, 25-32.

Pegmatite bodies both concordant and discordant types occur in and around Guwahati. These have intruded into the quartzofeldspathic gneiss and other related rocks of the amphibolite facies, along the planes of structural weakness of the F₂ and F₃ folding. The pegmatites are enriched in K-feldspar (about 40%) and other common minerals are quartz, plagioclase, micas. Lack of muscovite may be due to insignificant presence of metasedimentary rocks, prevalence of gneissic and migmatitic rocks, inconspicuos weathering/alteration of the pegmatitic bodies which expose no muscovitisation on the surface and non availability of vapour phase. Structure controlled pegmatites have no economic value other than the utilisation of the K-feldspar for high tension insulator.

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013978   Sharma K K;Padmakumari V M;Mallick K (Department of Applied Geology, University of Madras, Chennai-600 025) : Occurrence pattern of kimberlite pipes based on aeromagnetic images. J Geophys 1999, 20(4), 217-20.

Location of Kimberlite pipes by geophysical methods has assumed great importance in recent years. In an attempt to identify patterns in the occurrence of the Kimberlite pipes, the aeromagnetic map in the region around Wajrakarur, a well known diamond-producing area in Andhra Pradesh, India has been processed. The Wajrakarur Kimberlite pipes show an average age of 1091±15 million years. The basic aeromagnetic data and the residual map are presented in the image forms. It is observed that there is a definite pattern in the occurrence of the pipes 1,2,6 and 12 with regard to the magnetic and its residual maps. Since the Kimberlite is generally poor in iron content and rich in magnesium, the magentic low is the typical response of the Kimberlite pipes. A combination of positive and negative anomalies appear in the map due to the dipolar nature of the magnetic field.

013977   Sharma G S;Purohit R K;Roy M;Sengupta B;Singh J (Atomic Minerals Division, Department of Atomic Energy, , New Delhi-110 066) : Geochemistry and petrography of U-Th-Y mineralisation in alkali feldspar granite (alaskite) dykes around Dhanota, Mahendragarh district, Haryana, India. J Geol Soc India 2000, 55(2), 189-96.

Radioactive alkali feldspar granite (alaskite) occurs as dykes within the Proterozoic granite gneiss around Dhanota. Samples have assayed 0.011 to 0.16% U₃O₈ and 0.005 to 0.16% ThO₂. Yttrium values range from 250 to 800 ppm. Uranothorite occurs in association with zircon, xenotime, magnetite, hematite, sphene and goethite. The U-Th-Y mineralisation in alaskites of Dhanota is disseminated syn-magmatic intrusive type.

013976   Shankar D (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Seasonal cycle of sea level and currents along the coast of India. Curr Sci 1999, 78(3), 279-88.

Framework involving long baroclinic waves, which treats the north Indian Ocean as a single dynamical entity, has been remarkably successful in simulating the low-frequency, large-scale circulation in the ocean. It is, however, unable to simulate the observed seasonal cycle of sea level along the Indian coast. The reason appears to be the absence of salinity variation in these models. The large inflow of freshwater into the seas around India forces large changes in salinity, and hence, in coastal sea level.

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013975   Sastry K V;Rathee P (Department of Bio-Sciences, M D University, Rohtak-124 001) : Ground water quality in three villages of Rohtak district. J Nat Conserv 1999, 11(2), 175-82.

Hand pumps water used by villagers for drinking purposes was collected from three villages of Rohtak District and their physico-chemical characteristics - pH, dissolved oxygen, total dissolved solids, alkalinity, total hardness, Electrical conductivity, Salinity, potassium, sodium, calcium hardness, Magnesium, Chloride, Sulfate and Nitrate) were analysed and compared with I.S.I. standards for drinking water in order to find out whether this water was suitable for drinking purposes. The results obtained reveal that out of the three hand pumps selected, water of only one hand pump in each village was near to potability. On the basis of electrical conductivity and sodium absorption rate, the water can be classified into the `B' or normal type. It was noted in general that as compared to premonsoon season during the monsoon increase was recorded in total dissolved solids, pH, total hardness and alkalinity in all the selected sites.

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013974   Sarayanane N;Nandakumar K;Durairaj G;Nair K V K (Department of Zoology, University of Madras, Chennai-600 025) : Plankton as indicators of coastal water bodies during south-west to north-east monsoon transition at Kalpakkam. Curr Sci 2000, 78(2), 173-6.

In the coastal waters of Kalpakkam, a water body characterized by high salinity, rich nutrients and low temperature (southern-sub surface water SSW) was seen during the early half of September when the pole-ward current prevailed. This was replaced by low saline, low nutrient and relatively high temperature water (northern-surface water NSW) during early October when the current was equator-ward. This reversal in current direction is induced by the north-east monsoon winds during the SW to NWE monsoon transition. It is also observed that SSW in the Kalpakkam coast during the later half of September was characterized by the presence of pennate diatoms Nitzschia closterium, Asterionella glacialis and Thalassionema nitzschiodes. However, NSW in this coast in early October is characterized by the presence of centric diatom Skeletonema costatum. The two water bodies also have a characteristic zooplankton population, the SSW is rich in meroplankton and the NSW is poor in meroplankton. Thus, the pennate diatom N. closterium, A. glacialis and T. nitzschiodes would be considered as indicators of SSW and centric diatom S. costatum as the indicator of NSW.

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013973   Ravi Prakash M;Dimri V P (NO, National Geophysical Research Institute, Hyderabad-500 007) : Distribution of the aftershock sequence of the Latur earthquake in time and space by fractal approach. J Geol Soc India 2000, 55(2), 167-74.

Fractal dimensional analysis has been carried out on the aftershock sequence of the Latur earthquake (M_L 6.3) of September 30, 1993. Both the spatial and temporal correlation dimensions exhibit monofractal property. The spatial correlation dimension is found to be 1.75 indicating that the events tend to propagate in the whole region. The temporal correlation dimension is found to be 0.55 representing a non-continuous activity. The b-value obtained from the magnitude-frequency relation is found to be 0.56, which is typical of SCR seismicity. The focal depth-frequency analysis of the aftershocks showed that the lower boundary of the aftershock depth is about 7 km. The shallow depth of foci is a typical characteristic of the SCR seismicity. The fractal dimension obtained from the b-value is 1.12, which is close to 1, and reflects the `stable state' of the system and confirms that the main event belongs to SCR. The frequency-time distribution analysis of the aftershocks indicated that the earthquake generation process is not random. The parameter `p' of the modified Omori's formula for aftershock frequencies is estimated at 0.22.

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013972   Ravi Kumar M;Bhatia S C (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : New seismic hazard map for the Indian plate region under the global seismic hazard assessment programme. Curr Sci 1999, 77(3), 447-53.

New seismic hazard map for the Indian plate region, comprising the Himalaya, northeast India, the Indian shield, South China, Nepal, Burma and Andaman regions, was prepared under the Global Seismic Hazard Assessment Programme (GSHAP). A working catalogue of main shocks was obtained by merging the local catalogue of NOAA. Eighty-six potential seismic source zones were delineated based on the major tectonic features and seismicity trends. Using the probabilistic hazard assessment approach, the Peak Ground Accelerations (PGA) were computed for 10% probability of exceedence in 50 years, at locations defined by a grid of 0.5° x 0.5°. The PGA values over the grid points were contoured to obtain a seismic hazard map. The map reveals that the zones of highest risk are the Burmese arc, northeastern India and the Hindukush regions, with PGA values of the order of 0.35-0.4 g. Also, a majority of the north Indian plate boundary region and the Tibetan plateau region have a hazard level of the order of 0.25 g. In the Indian shield region, it is of the order of 0.05-0.1 g, whereas some locales like Koyna depict a hazard level of about 0.20 g.

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013971   Raval U (NO, National Geophysical Research Institute, Hyderabad-500 007) : Laterally heterogeneous seismic vulnerability of the Himalayan arc: a consequence of cratonic and mobile nature of underthrusting Indian crust. Curr Sci 2000, 78(5), 546-9.

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013970   Ramkumar M (NO, Delta Studies Institute, Andhra University, Visakhapatnam-530 003) : Recent changes in the Kakinada spit, Godavari delta. J Geol Soc India 2000, 55(2), 183-8.

Recent mapping of the Kakinada spit and the adjoining regions has revealed that the spit has reached its mature state and would not grow lengthwise. Another spit paralleling the Kakinada spit is growing to its east. Futuristic projections show that the new spit would form another bay like the Kakinada bay.

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013969   Ramesh Babu P V;Dhana Raju R (Atomic Minerals Directorate for Exploration and Research, DAE, , Nagpur-440 001) : Natural thermoluminescence of pegmatitic feldspars and quartz as an aid in exploration for rare element pegmatites: a case study of Bastar-Koraput pegmatite belt, central India. Indian J Geochem 1998, 13, 51-60.

Natural thermoluminescence (NTL) on pegmatitic feldspars (Perthitic Microcline and Albite) and quartz from the Bastar - Koraput Pegmatite Belt (BKPB) of central India shows that NTL of feldspars is marked by lower glow peak temperature (187-242±C; rarely 279°C) compared to that of quartz (220-313%C). With increasing internal evolution of pegmatitic melt that resulted in the progressive formation of barren (type I) to rare element mineralised pegmatites (type II to V), there is an increase in the intensity of NTL glow peak of feldspars and to a lesser extent of quartz. Thus, perthite with glow peak of 3.9 to 9.0 mV intensity at 187-229°C, albite with 0.3 to 1.9 mV at 210-279°C and quartz with upto 27 mV at 220-313°C indicate mineralized nature (Nb-Ta, Sn, Be, Li) of pegmatites emplaced in amphibolites. NTL of pegmatitic feldspars and quartz can be used as an aid to discriminate the mineralized from the barren pegmatites in other areas with similar geological set up.

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013968   Ramaprasada Rao I B;Venkata Chary M;Mathur R R;Srinivas S (Centre of Exploration Geophysics, Department of Geophysics, Osmania University, Hyderabad-500 007) : Near field CSAMT resistivity and model parameter determination. Curr Sci 2000, 78(5), 601-7.

Cagniard resistivity approach in controlled source audio-frequency magnetotellurics/magnetotellurics (CSAMT/MT) data handling assumes a plane wave EM source. Hence, near field Cagniard's resistivity does not permit the determination of model parameters. Presents the study of near/transition field apparent resistivity over milti-layered media by resorting to near field apparent resistivity and examines the possibility of extracting model parameters from near field CSAMT data, which hitherto has been ignored or corrected, using the well-known Marquardt algorithm. The per cent deviation (Δα%) between the true and fitted geoelectric parameters for a two-layer case increases with increase in ρ2/ρ when (ρ2 <60> ρ1) for all values of r/h1, h1 being the thickness of the first-layer and r the distance between the transmitter and receiver. When r/h1, h1 <62><62> 1, Δα% is well below 15%. In case ρ2 <62> ρ1, the percent deviation is within 5% when ρ2/ρ1 20 and r/h1≥ 1. Over a three-layer geoelectric section the per cent deviation is within the `acceptable' limits for the geoelectric parameters studied.

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013967   Ramachandran C;Kesavamani M;Prasad R M C (Geophysics Division, Geological Survey of India, , Bandlaguda Complex, Hyderabad-500 068) : Geophysical prognostication of primary diamond deposits in Peninsular India. J Geophys 1999, 20(4), 155-78.

Low heat flow regions, deep-seated basement fractures/fault corridors and linear grabens are important large-scale controls for diamond deposits. Dome or ring shaped features, fault systems arranged in radial patterns, minor dome shaped features within the main dome, splay faults of major fault corridors, dilation jogs created by strike slip movements or fault/ fractures, internal shears and cross cutting structures in major structural lineaments, contiguous fault zones and intersection of contiguous faults, form the regional and local controls of the exploration model. The heat flow and regional gravity maps of India, and the available gravity and magnetic maps of Wajrakarur, Chigicherla, Maddur, Raipur and Panna areas are re-interpreted to recognize some of the above controls for diamond deposits. The geophysical signature of kimberlites and lamproites can be highly varied. 12 types of contour patterns are recognized from the gravity and magnetic maps of Peninsular India, that may reflect the kimberlite fields/ clusters and individual pipes, and on this basis, several areas with potential for diamond deposits are delineated. The proposed integrated strategy significantly increases the chances for future discovery of diamond deposits in Peninsular India.

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013966   Raju G;Reddy Y;Naidu S V (Department of Applied Geology, S.V. University, P.G. Centre, Cuddapah-516 003) : Ground water quality and its utilisation for agricultural operations in Rajampet taluk, Cuddapah district, Andhra Pradesh, South India. Indian Pumps 1998, 30(1), 5-10.

Chemical quality of natural waters should receive as much importance as the quantity of water available at a place. The required quality of water supply depends primarily on its use. The criteria fixed for water used for drinking differ significantly from those fixed for that used for irrigation and industrial use. Like any other part of rural Inida, the economy of the Taluk is essentially agrarian based on availability of water of adequate quality and quantity for public supplies and the irrigation, is the major constraint for its development. Study reveals that local environment influences the quality of water and its use for domestic and agricultural purposes. The ground water samples from the wells of Rajampet Taluk are collected and the chemical analysis for various parameters are carried out. The laboratory analysis and the interpretation of the sample are systematically carried out and the results are represented numerically and graphically.

013965   Rajpal Singh;Birpal Singh (Department of Physics, R.B.S. College, Bichpuri, Agra-283 105) : Detection and identification of VLF seismo-electromagnetic signals. Curr Sci 2000, 78(4), 492-8.

Vertical electric field components of the electromagnetic emissions associated with earthquakes have been monitored at the Agra station (geographical lat. 27.2°N, geographical long. 78°E) since February 1998 using a borehole antenna. Analysis of one year of data has shown that large variations in the electric field occurs, mostly in the form of noise bursts, both prior to and after the occurrence of major earth-quakes. Some selected cases of noise bursts have been chosen to identify the wave-forms of seismogenic emissions and find that among various types of noise bursts recorded, the seis-mogenic noise bursts are either slowly varying, square wave patterns, or periodic variations. The long distance propagation of such signals is interpreted in terms of waveguide mode propagation through conductive channels across the main boundary seismic fault existing from the north-west to the north-east around 200 km from the observing station.

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013964   Premkumar K;Ravichandran M;Kalsi S R;Sengupta D;Gadgil S (NO, National Institute of Ocean Technology, IIT Campus, Chennai-600 036) : First results from a new observational system over the Indian seas. Curr Sci 1999, 78(3), 323-30.

Department of Ocean Development has recently installed several moored met-ocean buoys in the Bay of Bengal and Arabian Sea to measure sea surface temperature (SST) and other near surface atmospheric and oceanic variables every three hours. A preliminary analysis of the data from one buoy in the Arabian Sea and three buoys in the Bay of Bengal, during June-August 1998, along daily INSAT data on outgoing longwave radiation at the buoy locations. Data show that SST dropped abruptly in the eastern Arabian Sea during passage of the June 1998 cyclone. In the Bay of Bengal, SST shows prominent intraseasonal oscillations at all three buoy locations. The SST variation seems to be determined by variations in cloudiness and wind speed at the buoy locations.

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013963   Nayak S S;Rao K R P;Kudari S A D;Ravi S; Kulshrestha S K;Bhaskar Rao K S (Geological Survey of India, , Hyderabad-500 068) : Search for kimberlites in the eastern block of the Dharwar Craton : a conceptual model. J Geophys 1999, 20(4), 195-203.

Dharwar Craton, hosting the historically world famous South Indian Diamond Province, in endowed with both primary (kimberlites and lamproites) and secondary (conglomerates and gravels) sources of diamond. The primary source rocks are extremely rare, small volume igneous bodies of mantle origin and are preferred to secondary sources for exploitation world over. Because of their small areal extent and rarity of occurrence a successful programme of search for primary sources in vast continental regions has to be concept oriented. A conceptual model for locating kimberlites in the eastern block of Dharwar Craton is proposed. Emplacement of kimberlites in the eastern block of the Dharwar Craton is controlled mainly by the major ENE-WSW to E-W trending basement faults which were reactivated around 1100 Ma period evidences of which are recorded in the sediments of the Cuddapah Basin. It is proposed that emplacement of kimberlites in the Archean granite-greenstone terrain of the eastern block of the Dharwar Craton is caused by the reactivation of the major ENE-WSW to E-W trending basement faults during the culmination of the Eastern Ghats Orogeny. Intersections of these faults with the NW-SE trending major faults and closure parts of the structural domes formede favourable loci for emplacement of kimberlites.

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013962   Naqvi S W A;Jayakumar D A (NO, National Institute of Oceanography, Dona Paula, Goa-403 004) : Ocean biogeochemistry and atmospheric composition: significance of the Arabian Sea. Curr Sci 1999, 78(3), 289-99.

Arabian Sea is an important site of biogeochemical ocean-atmosphere transfers, which play a crucial role in regulating the atmospheric chemical composition and the earth's climate. Widespread denitrification resulting from an intense oxygen-deficiency at mid-depths in this region modulates ocean combined nitrogen inventory and consequently biological productivity. Due to a delicate bio-geochemical balance the Arabian Sea is expected to be among the first to react to potential anthropogenic perturbations.

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013961   Nagar S G;Tyagi A;Seetaramayya P;Singh S S (NO, Indian Institute of Tropical Meteorology, Pashan, Pune-411 008) : Evolution of an atmospheric boundary layer at a tropical semi-arid station, Anand during boreal summer month of May. Curr Sci 2000, 78(5), 595-600.

Evolution of an Atmospheric Boundary Layer (ABL) over a semi-arid land station, Anand, (22°35'N, 72°55'E, 45.1 m asl) in India, during the summer month of May, is examined using surface meteorological and radiosonde temperature and humidity data collected during LASPEX-97 for a 5-day period from 13-17 May 1997. These 5 days remained undisturbed, and clear sky weather conditions prevailed. However, the data obtained on these days are helpful in understanding the diurnal variation of the ABL over a land station. There are 5 observations per day at an interval of 3h beginning with 0530 IST. The 0530 IST ascent are chosen to find out the initial ABL heights which exhibit the nocturnal cooling conditions. It is observed from the analysis of θv, θe, θes, q, and P profiles that the nocturnal boundary layer is stable with an inversion close to the ground. The top of an inversion layer is characterized by a θe minimum and a θes maximum. After dawn, the ABL grows to a height of 827 m at 030 IST. Aloft, a residual layer up to ~ 3200 m is observed. The daytime strong insolation causes formation of an unstable boundary layer close to the ground at 1130 IST with an elevated stable layer between 550 and 930 m. It is only by 1430 IST that the stable layer gets completely wiped out and a convective mixed layer develops up to a height of 3280 m...

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013960   Mukherjee S (School of Environmental Sciences, J.N.U., New Delhi-110 067) : Occurrences of Nb-Ta bearing minerals in Jorasemar area, district Hazaribagh, Bihar. Indian J Geochem 1998, 13, 61-6.

Composite pegmatites and aplite veins from Haraia village near Jorasemar contain discrete seggregations of tantalo columbium minerals. The pegmatites are commonly zoned and the composite character is mostly observed in the border zones. The core-zone is of aquo-igneous character where columbite and other rare earth minerals occur. The identification of these minerals and their relative concentration is studied by G-M counter and advance CGS counter. IRS-IA data revels scanty vegetation surrounding the Nb-Ta mineral bearing pegmatites. The occurrences of columbite and monazite as aggregates from alluvium of Pandaria and Jorasemar areas have also been collected, which suggests to be derived from these pegmatites.

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013959   Muggeridge M T (Horizon Enterprises International PL, , Suite 5, 286 Fitzgerald Street, Perth, Western Australia) : Sampling techniques for locating primary sources of diamond: pathfinder methods for recovery of diamonds, indicator minerals, and geochemical signatures. J Geophys 1999, 20(4), 221-39.

Tracking down a primary diamond-bearing source entails detecting and systematically following a weak trail of subtle clues, before a final target for testing is struck. Pathfinder minerals and elements are important in this search as they provide direct evidence of the presence of their host. Heavy mineral sampling to detect indicator minerals and diamonds is a particularly useful and broadly applied technique which has led to the discovery of many mines in various parts of the world. Critical aspects of heavy mineral sampling methodology include sample selection, size, spacing and processing. Special attention must be paid to the selection and evaluation of trap sites during drainage sampling. Geochemical and geobotanical exploration methods have a more restricted use in diamond exploration programmes. Forethought ad meticulous attention to detail are required when planning and conducting each phase of an exploration programme involving any of the pathfinder sampling techniques, as well as in the analysis of samples and in progressive interpretation of results. Effectiveness of each stage of a diamond exploration programme is directly related to the reliability of the results it generates, which in turn are vital to the decision as to whether or not further exploration is warranted.

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013958   Manjunatha B R;Shankar R (Department of Marine Geology, Mangalore University, Mangalagangotri-574 199) : Behaviour and distribution patterns of particulate metals in estuarine and coastal surface waters near Mangalore, Southwest coast of India. J Geol Soc India 2000, 55(2), 157-66.

Physico-chemical properties of water (pH, dissolved oxygen, salinity and suspended matter concentrations) and geochemistry (Cu, Pb, Zn, Ni, Co, Mn, Fe, Al, Ca and loss-on-ignition) of suspended particulates have been measured for the first time in the Netravati-Gurpur estuary and the adjacent coastal environment, southwestern India. The main objective was to understand the influence of physico-chemical properties of estuarine and coastal waters on the behaviour, association and dispersal patterns of particulate metals. Suspended particulate matter (SPM) from the estuarine and coastal environments have higher Cu, Pb and Zn (by factors of 1,5-2.7) than the Netravati-Gurpur riverine SPM, indicating enrichment of these metals with increasing salinity. In contrast, Al, Fe, Mn, Co and Ni contents and the corresponding metal/Al ratios are marginally lower (by factors of 1.1-1.5) than those for riverine SPM, suggesting not only a decrease of terrigenous influx seaward, but also removal of trace metals from the particulate phase. R-mode factor analysis of the data has shown that detrital particles (with Fe oxide coating), clays and Mn-Oxide are the major factors that control particulate metal association. Factor score distribution patterns suggest that detrital particles coated with Fe oxide are deposited in the estuary and nearshore region, whereas clays and Mn-oxide seem to be transported further into the coastal sea....

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013957   Mallikharjuna Rao J;Chetty T R K (NO, National Geophysical Research Institute, Hyderabad-500 007) : Pegmatitic and granitic rocks of Nellore-Gudur area Andhra Pradesh. Indian J Geochem 1998, 13, 1-15.

The youngest phase of igneous activity of the region resulting in the emplacement of pegmatites of different size and shape, into schistose rocks of Nellore schist belt. The pegmatites are grouped into Tadpatri, Podalakur, Kalichedu and Saidapuram pegmatite zone considering their geological and structural trends. Zoned pattern of mineralogical association within the pegmatites and a regional zoned pattern of pegmatites in terms of ruby-mica rich pegmatites at the central part followed by green-mica pegmatites and at the peripheral pink potash-feldspar pegmatites are noticed in the region. Granitic rocks occur as batholithic type and granitised type and range from alkali-granite, granite to granodiorite in composition. They show both I-type and S-type of origin and most of them belong to anorogenic granites. U and Th elements vary considerably in the granitic rocks (U range from 0.5 to 5 ppm and Th range from 3.4 to 71.5 ppm) and in pegmatites (U range from 1 to 650 ppm and Th range from 1 to 6451 ppm). The fluids might have played a major role in mineral growth and crystallization of radioactive rare minerals within these pegmatites.

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013956   Kulkarni A K;Mandal B N;Sangam R B (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Analysis of a heavy rainspell of monsoon 1995 over Punjab and Haryana regions. Indian J Pwr River Valley Dev 1999, 49(3-4), 54-7.

013955   Kuity D P;Verma K K (SOS in Geology and WRM, Pt. R.S. University, Raipur) : Acid magmatism in Bastar region. Indian J Geochem 1998, 13, 67-74.

Bastar region (M.P.) has experienced tectonism, metamorphism acid magmatism and synkinematic granitization. Acid magmatic activity (synkinematic took place broadly in three phases. The mutual cross cutting and intrusive relation, nature of metamorphism and granitization and their mode of occurrences in the field have helped to distinguish these chronologically different granitic bodies. Post-kinematic granitoids are more suitable for accumulation of tin and other rare metals.

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013954   Kayal J R (Geological Survey of India, , 27 J.L. Nehru Road, Calcutta-700 016) : Seismotectonic study of the two recent SCR earthquakes in central India. J Geol Soc India 2000, 55(2), 123-38.

Seismotectonics of the two recent earthquakes, 1993 Killari, m_b 6.3 and 1997 Jabalpur, m_b 6.0, are examined to understand the nature of seismicity and generating process of the Stable Continental Region (SCR) earthquakes in central India. The Killari earthquake and its aftershocks are confined to a shallower depth (0-15 km), a common type of SCR events, whereas the Jabalpur earthquake and its aftershocks occurred at a deeper depth (35-40 km), uncommon in SCR seismicity. The frequency-magnitude relation (b-value) estimated for the two aftershock sequences is compatible (0.46 and 0.49), and is typical for a SCR. The attenuation rates (p-value) of the aftershocks are, however, very much different; it is low (0.27) for the Killari aftershock sequence and high (1.30) of the Jabalpur sequence; the aftershocks continued for about six months in the Killari area, whereas it died down within one and a half months in Jabalpur area for almost a similar magnitude of the main shock. The maximum intensity reached VIII for both the main shocks. Falut-plane solutions of the Killari earthquakes reveal reverse faulting for the main shock and the deeper aftershocks (depth 6-15 km) and strike-slip faulting for the shallower aftershocks (0-5 km)....

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013953   Kailas S V;Narasimha R (Centre for Civil Aircraft Design and Development, National Aerospace Laboratories, Bangalore-560 017) : Quasi-cycles in monsoon rainfall by wavelet analysis. Curr Sci 2000, 78(5), 592-5.

Indian rainfall data over the period 1870 to 1990 have been analysed using continuous wavelet transforms. Results obtained are found to be particularly revealing with regard to the temporal structure of the time series if local scaling is used for the transform coefficients, normalizing their values at any wavelet scale with the maximum at that particular scale. Tracking the maxima in such normalized values lead to a picture of seven prominent modes, which are modulated in wavelet scale (and hence also frequency) and in amplitude. Because the modes wander over the parameters of the wavelet map, they cannot always be easily detected by classical spectral analysis. The quasi-cyclic modes so identified exhibit appreciable jitter, and have average periods varying from a little less than 2 years to nearly 80 years.

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