001467   Navalgund R R;Singh R P (NO, Space Applications Centre (ISRO), Ahmedabad-380 015, Email: director@sac.isro.gov.in) : Evolution of the earth observation system in India. J Indian Inst Sci 2010, 90(4), 471-88.

The Indian Earth Observations Programme has been applications- driven and national development has been its prime motivation. From the experimental satellite Bhaskara-l launched in 1979 to the recent Cartosat-2B launched in July 2010, India's Earth Observations capability has increased manifold. The Enhancement in observation capabilities are not only in spatial, spectral, temporal and radiometric resolutions, but also in their coverage and value-added products. The sensors built over this period provide observations over land, atmosphere and oceans in visible, infrared, thermal and microwave regions of the electro magnetic spectrum. Earth Observation data has been extensively used in inventories, monitoring and conservation plans of various natural resources of the country for societal benefits. An institutional mechanism for the absorption of technology at different levels of governance in the country has been built through the concept of the National Natural Resources Management System. The Establishment of various centres/institutions in different states, central agencies as well as academic and research institutions has helped capacity building in the area of remote sensing technology and applications programmes. The paper reviews the evolution of the Earth Observation System in the country in the last three decades and briefly discusses future directions.

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001466   Narasimha R (NO, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore, Email: roddam@caos.iisc.ernet.in) : Recent national initiatives in earth science. J Indian Inst Sci 2010, 90(4), 453-6.

This article describes briefly the background to the significant new national initiatives taken with regard to the earth sciences in India.

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001465   Nair R R; (Ocean Engineering Dep, Indian Institute of Technology, Madras, Email: rajeshnair.iitkgp@gmail.com) : Subsurface signatures and timing of extreme wave events along the southeast Indian coast. J Earth Syst Sci 2011, 120(5), 873-83.

Written history's limitation becomes apparent when attempting to document the predecessors of extreme coastal events in the Indian Ocean, from 550-700 years in Thailand and 1000 years in Indonesia. Detailed ground-penetrating radar (GPR) surveys in Mahabalipuram, southeast India, complemented with sedi-mentological analyses, magnetic susceptibility measurements, and optical dating provide strong evidence of extreme wave events during the past 3700 years. The diagnostic event signatures include the extent and elevation of the deposits, as well as morphologic similarity of buried erosional scarps to those reported in northern Sumatra region. Optical ages immediately overlying the imaged discontinuities that coincides with high concentration of heavy minerals date the erosional events to 340 ± 35, 350 ± 20, 490 ± 30, 880 ± 40, 1080 ± 60, 1175 ± 188, 2193 ± 266, 2235 ± 881, 2489 ± 293, 2450 ± 130, 2585 ± 609, 3710 ± 200 years ago. These evidences are crucial in reconstructing paleo extreme wave events and will pave the way for regional correlation of erosional horizons along the northern margin of Indian Ocean.

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001464   Nagendra R;Patel S J;Rakesh Deepankar;Reddy A N (Geology Dep, Anna Univ, Channai-600 025) : Bathymetric significance of the ichnofossil assemblages of the Kulakkalnattam sandstone, Ariyalur area, cauvery basin. J Geol Soc India 2010, 76(5), 525-32.

Well preserved ichnofossils were found in Kulakkalnattam sandstone exposed at Kulakkalnattam stream in Ariyalur area, Cauvery Basin. It consists of infaunal structures of both suspension and deposit feeders. Five ichnofossils are present in a fine to coarse grain sandstone which includes Ophiomorpha, Palaeophycus, Planolites Skolithos, and Thalassinoides. The study infers that ichnofossils Skolithos and Ophiomorpha are infaunal colonization of the suspension feeders in high energy condition in shifting substrate, whereas Thalassinoides and Planolites-Palaeophycus ichnofossils indicate infaunal deposit feeders living at the sediment-water interface in low to moderate energy conditions. Furthermore, the abundance and diversity of the trace fossils indicates there was alternatively fluctuations in energy conditions which lead to development of Skolithos and Cruziana ichnofacies type condition during the deposition of Kulakkalnattam sandstone in foreshore-shoreface environments.

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001463   Muthukrishnan A;Aruchamy S (NO, Periyar EVR College, Bharathidasan University, Tiruchirapalli, Email: geomks16@gmail.com) : Status of coastal ecosystems through geospatial techniques for degraded coast of Gulf of Mannar. Int J Geomatics Geosci 2012, 3(1), 134-56.

This region is defined here as Tuticorin Coast, India, and their outlying islands. Tuticorin Coast climate is strongly influenced by the surrounding sea water. Key climatic features include tropical cyclones and monsoons in entire; migratory equatorial storm systems in the west, including mainland; and the temperature oscillation phenomenon, which causes floods and prolonged droughts, especially in southern part of Tuticorin Coast. Unfortunately, the Tuticorin Coast has well-developed coastal ecosystem (geomorphological landforms on the land and sea side) is dominated by coastal climate, it reaching elevations of 2-28m. Tuticorin Coast, the area for the present study is located in the south eastern coastal zone of Tamil Nadu State in India. It lies between 8° 4'49" N - 9° 22'20" N latitudes and 78° 3'56" E-79° 26'6" E longitudes, covering an area of 1437.20Sq.km. Much of the study area is undeveloped and retains a wide array of coastal land forms in near natural condition. However, there are a number of residential communities, primarily on the very near to the coast, that have altered the climate and ecosystem processes.

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001462   Murugavel P;Chate D M (NO, Indian Institute of Tropical Meterology, Pune-411 008, Email: chate@tropmet.res.in) : Volatile properties of atmospheric aerosols during nucleation events at Pune, India. J Earth Syst Sci 2011, 120(3), 347-57.

Continuous measurements of aerosol size distributions in the mid-point diameter range 20.5-500 nm were made from October 2005 to March 2006 at Pune (18°32'N, 73°51'E), India using Scanning Mobility Particle Sizer (SMPS). Volatilities of atmospheric aerosols were also measured at 40°125° 175°, 300° and 350°C temperatures with Thermodenuder-SMPS coupled system to determine aerosol volatile fractions. Aerosols in nucleated, CCN and accumulated modes are characterized from the measured percentage of particles volatized at 40°, 125°, 175°, 300° and 350°C temperatures. Averaged monthly aerosol concentration is at its maximum in November and gradually decreases to its minimum at the end of March. The diurnal variations of aerosol concentrations gradually decrease in the night and in early morning hours (0400-0800 hr). However, concentration attains minimum in its variations in the noon (1400-1600 hr) due to higher ventilation factor (product of mixing height and wind speed). The half an hour averaged diurnal variation of aerosol number concentration shows about 5 to 10-fold increase despite the ventilation factor at higher side before 1200 hr. This sudden increase in aerosol concentrations is linked with prevailing conditions for nucleation bursts. The measurement of volatile fraction of ambient aerosols reveals that there are large number of highly volatile particles in the Aitken mode in the morning hours and these volatile fractions of aerosols at temperatures <60>150°C are of ammonium chloride and ammonium sulfate, acetic and formic acids.

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001461   Muralitharan J;Palanivel K (NO, Centre for Remote Sensing, Bharathidasan University, Tiruchirappalli, Email: muralitharangeo@gmail.com) : GIS based lineament Delineation using geophysical resistivity data, Karur district, Tamil Nadu, India. Int J Geomatics Geosci 2012, 3(1), 167-77.

Shows that geophysical resistivity values Digital Elevation Model (DEM) for different depths, can indicate the location of depth persistence lineaments. The depth persistence lineaments allow large scale migration of groundwater and can be used as sites for the artificial recharging of aquifers. It is concluded that the lineament maps prepared from geophysical resistivity values can give a better picture of the depth persistence.

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001460   Mukhopadhyay G;Mukhopadhyay S K;Roychowdhury M;Parui P K (Geological Survey of India, Coal Wing, DK-6 Sector-II, Salt Lake, Kolkata-700 091, Email: manasmayukh@gmail.com) : Stratigraphic correlation between different Gondwana basins of India. J Geol Soc India 2010, 76(3), 251-66.

Gondwana Basins of India occur within the suture zones of Precambrian cratonic blocks of Peninsular India along some linear belts. More than 99% of the total coal resource of the country is present within these basins. The basins are demarcated by boundary faults having graben or half-graben geometry. These basins preserve a thick sedimentary pile deposited over nearly 200 million years from latest Carboniferous to Lower Cretaceous. However, due to lack of well-constrained data, age of most of the formations is assigned tentatively. This has resulted in diversified views on both intra- and inter-basinal stratigraphic correlation particularly in case of Upper Gondwana formations. It is well recognised that there are distinct spatial and temporal similarities in lithological, faunal and floral distribution in different Gondwana Basins of southern continents, including India, that were once part of supercontinent Gondwanaland. To address the problems of Indian Gondwana stratigraphy, during the present study, some unique events, also recognised in other parts of Gondwanaland, like marine flooding surfaces, large scale tectonic events or major change in depositional environment have been used as a tool for temporal correlation within the Gondwana Basins of India. Many of these events have been dated from different basins elsewhere. Considering these major events as time planes the total time span of deposition in Gondwana Basins has been classified into seven time slots. Recognition of these time planes helps in interbasinal correlation of different formations in Indian Gondwana basins and assigning the age, wherever available. This approach also helps in better understanding of basinal history. Unless otherwise mentioned, the time scale proposed by International Commission on Stratigraphy (2004) has been followed in this paper.

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001459   Mishra D C (NO, National Geophysical Research Institute (CSIR), Hyderabad-500 007, Email: dcm_ngri@yahoo.co.in ) : Long hiatus in proterozoic sedimentation in India: Vindhyan, Cuddapah and Pakhal basins- a plate tectonic model. J Geol Soc India 2011, 77(1), 17-25.

Most of the Proterozoic basins in India, viz. the Vindhyan, the Cuddapah and the Pakhal Basins have experienced long hiatus between the upper and the lower group of rocks. It is proposed that the older group of rocks of Paleoproterozoic period (<126>1.9-1.6 Ga) formed during the rifting phase caused by large scale magmatism in respective basins possibly due to plume tectonics. On the other hand, the younger group of rocks of Neoproterozoic (<126>1.0-0.7 Ga) are formed during the final phase of convergence after mountain building that supplied sediments. These geological processes explain large scale disturbances in the older group of rocks during subsequent convergence and collision as they usually occurred along the rifted margins of the cratons. These processes also explain the undisturbed nature, devoid of magmatic rocks of the younger group of rocks and hiatus of about 0.5-0.6 Ga in each case. It is suggested that the plume that was responsible for these rifting of the Indian cratons during Paleo-Mesoproterozoic might have also been responsible for the break up of contemporary Columbian agglomeration in this section. Same model can be used to explain the formation of Proterozoic basins and related hiatus any where else where similar geological environment exist.

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001458   Mishra A P;Pandey A C;Rai S (Nehru Science Center, Allahabad Univ, Allahabad-211 002, Email: anshu_786@rediffmail.com) : Ocean model derived global surface circulation and vertical velocity. J Geol Soc India 2010, 76(5), 468-78.

Authors examine Sea surface temperature (SST), Sea surface circulation (SSC) and Vertical velocity (VV) fields from simulation of 25 layers coarse resolution Modular ocean model (MOM version 3.0) with prescribed wind forcing for the region 74.25°S to 65°N, 180°W-180°E. It is found that distribution of SST simulated by the model shows its consistency with the observed climatology. However, simulated SST in the areas of Arabian Sea, Bay of Bengal, Indonesian Throughflow (ITF) region and east of North America near equator exhibit slight warming with respect to observation, which may be due to model deficiency and forcing problems. Circulation features suggest that one of the strongest current viz. Antarctic circumpolar current (ACC) along with other major current systems viz. Gulf stream current, North and South Pacific current, Agulhas current, Labrador current, Canary current, etc are captured well by the model. In the Indian Ocean and other ocean basins, current patterns are well captured by the model simulation. Intense upwelling as well as downwelling areas is marked in the horizontal distribution of VV, which is as expected. VV show quasi-stagnant and convergent regions suggesting that floating materials may be accumulated during January/July in the real ocean and wind driven circulation may act as an important contribution for such transport of floating materials in these regions. An attempt has also been made to understand the fluctuations of the SST in NINO 3.4 region during the period of model simulation using SST * anomalies.

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001457   Manimaran G;Antony Ravindran A;Selvam S; Manimaran D;Sugan M (Geology Dep, School of Tectonics, V.O. Chidambaram College, Thoothukudi, Email: acugemmani@yahoo.co.in) : Characterization and disaster management of landslides in the Nilgiris mountainous terrain of Tamil Nadu, India. Int J Geomatics Geosci 2012, 3(1), 1-12.

Steep slope, steep dips of the lithotypes, presence of clay layering in weathered rock types, events of continuous heavy rains, flooding on the slopes and improper land use practices play a major role in the genesis of landslides in the Nilgiris. Recent enhancement in the events of the landslides in the Nilgiris is mainly due to ongoing Seismotectonic activities in Southern Granulite Terrain (SGT) of South India and reactivation of hidden blind shear zones of Nilgiri Hills. Mitigation measures are highlighted.

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001456   Mani K (Geography Dep, University College, Trivandrum, Email: maniutycollege@gmail.com) : Land use and land cover changes detection using multi temporal satellite data Devikulam taluk, Idukki district, Kerala. Int J Geomatics Geosci 2012, 3(1), 157-66.

All exploit natural forest in unscientific way in search of profits and means of subsistence. Forest deterioration is a complex socio-economic, cultural and political event. An assessment of the forest deterioration is not an easy task. Much of the human induced deforestation and forest degradation is in varying degrees, economically wasteland and environmentally negative as well as socially undesirable. The area selected for the present study is Devikulam taluk of Idukki district in the State of Kerala. It is situated in Western Ghats, which is considered as one of the sixteen threatened ecological locations in the world. The study area stretched between the latitudes of 9056'56" to 10021'24" N and longitudes of 770 48' 31" to 770 16' 14" E covers an area of 1140.29 km2 and is inhabited by 1, 85,103 persons (2001). Focuses on migration, plantation agriculture, tourism, construction of roads, and other physical infrastructure are the major causes of forest deterioration in the study area. These hills were not mentioned in the earlier records. The kings were considered the high land area was worthless (Ward 1817). More than a hundred and fifty years ago the scenery of the study area was entirely different from present. Toposheets, remote sensing, field sampling, and census data are used for analysis of the present study.

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001455   Maneesha K;Sarma V V S S;Reddy N P C;Sadhuram Y;Ramana Murty T V;Sarma V V;Dileep Kumar M (NO, National Institute of Oceanography (Council of Scientific and Industri, 176 Lawsons Bay Colony, Visakhapatnam-530 017, Email: sarmav@nio.org) : Meso-scale atmospheric events promote phytoplankton blooms in the coastal Bay of Bengal. J Earth Syst Sci 2011, 120(4), 773-82.

The Bay of Bengal is considered to be a low productive region compared to the Arabian Sea based on conventional seasonal observations. Such seasonal observations are not representative of a calendar year since the conventional approach might miss episodic high productive events associated with extreme atmospheric processes. We examined here the influence of extreme atmospheric events, such as heavy rainfall and cyclone Sidr, on phytoplankton biomass in the western Bay of Bengal using both in situ time-series observations and satellite derived Chlorophyll a (Chi a) and sea surface temperature (SST). Supply of nutrients through the runoff driven by episodic heavy rainfall (234 mm) on 4-5 October 2007 caused an increase in Chi a concentration by four times than the previous in the coastal Bay was observed within two weeks. Similar increase in Chl a, by 3 to 10 times, was observed on the right side of the cyclone Sidr track in the central Bay of Bengal after the cyclone Sidr. These two episodic events caused phytoplankton blooms in the western Bay of Bengal which enhanced <126>40% of fishery production during October-December 2007 compared to that in the same period in 2006.

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001454   Maibam B;Goswami J N;Srinivasan R (NO, Physical Research Laboratory, Ahmedabad-380 009, Email: bmaibam@yahoo.com ) : Pb-Pb zircon ages of archaean metasediments and gneisses from the Dharwar craton, southern India: implications for the antiquity of the eastern Dharwar craton. J Earth Syst Sci 2011, 120(4), 643-61.

²⁰⁷Pb-²⁰⁶ Pb ages of zircons in samples of metasediments as well as ortho- and para-gneisses from both the western and the eastern parts of the Dharwar craton have been determined using an ion microprobe. Detrital zircons in metasedimentary rocks from both yielded ages ranging from 3.2 to 3.5 Ga. Zircons from orthogneisses from the two parts also yielded similar ages. Imprints of younger events have been discerned in the ages of overgrowths on older zircon cores in samples collected throughout the craton. Our data show that the evolution of the southwestern part of eastern Dharwar craton involved a significant amount of older crust (<62>3.0 Ga). This would suggest that crust formation in both the western and eastern parts of the Dharwar craton took place over similar time interval starting in the Mesoarchaean at ca. 3.5 Ga and continuing until 2.5 Ga. Our data coupled with geological features and geodynamic setting of the Dharwar craton tend to suggest that the eastern Dharwar craton and the western Dharwar craton formed part of a single terrane.

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001453   Lalitha A;Lakshumanan C;Suvedha M;Suganya M; Udayaganesan P (NO, Centre for Remote Sensing, Bharathidasan University, Tiruchirappalli, Email: lalithashreya2004@yahoo.co.in) : Evaluation of ground water pollution in alluvial and crystalline aquifer by principal component analysis. Int J Geomatics Geosci 2012, 3(1), 285-98.

In order to evaluate the groundwater pollution, the application of statistical principal components analysis (PCA) was used as one useful tool. PCA was based on the physical-chemical data of groundwater samples in the aquifers. Three components were obtained in the study area. PC - 1 accounts for 36% of the total variance due to the high loadings in Na, Cl, Ca, Mg, and HCO3. PC - 2 represents 24% of the total variance and shows high loadings for SSP, K Ratio, SAR and Na % and PC - 3 is dominated by high loadings in K and SO₄. The principal components analyses indicate water-rock interaction process as the major mechanism responsible for the groundwater salinity (mainly sodium-bicarbonate type), invoking the lithological composition dominated by feldspathic mineral group. This analysis led to the conclusion is two major sources of contamination play a major in the groundwater pollution in the area: fertilizers, pesticides and insecticides used in agricultural activities, and non-point natural sources.

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001452   Kulkarni A V (Divecha Center for Climate Change, Indian Institute of Science, Bangalore-560 012, Email: anilkulkarni@caos.iisc.ernet.in) : Monitoring Himalayan cryosphere using remote sensing techniques. J Indian Inst Sci 2010, 90(4), 457-69.

In the Himalayas, large area is covered by glaciers, seasonal snow and changes in its extent can influence availability of water in the Himalayan Rivers. In this paper, changes in glacial extent, glacial mass balance and seasonal snow cover have been discussed. Field and satellite based investigations suggest, most of the Himalayan glaciers are retreating though the rate of retreat is varying from glacier to glacier, ranging from few meters to almost 50 meters per year, depending upon the numerous glacial, terrain and meteorological parameters. Retreat was estimated for 1868 glaciers in eleven basins distributed across the Indian Himalaya since 1962 to 2001/02. Estimates show an overall reduction in glacier area from 6332 to 5329 sq km, an overall deglaciation of 16 percent. Snow line at the end of ablation season on the Chhota Shigri glacier suggests a change in altitude from 4900 to 5200 m from late 1970's to the present. Seasonal snow cover monitoring of the Himalaya has shown large amounts of snow cover depletion in early part of winter, i.e. from October to December. For many basins located in lower altitude and in south of Pir Panjal range, snow ablation was observed through out the winter season. In addition, average stream runoff of the Baspa basin during the month of December shows an increase by 75 per cent. This combination of glacial retreat, negative mass balance, early melting of seasonal snow cover and winter time increase in stream runoff suggest an influence of climate change on the Himalayan cryosphere.

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001451   Krishna Kumar;Gupta P K;Sri Niwas (Earth Sciences Dep, Indian Institute of Technology Roorkee, Roorkee-247 667, Email: srsnpfes@iitr.ernet.in) : Efficient two-dimensional magnetotellurics modelling using implicitly lanczos method. J Earth Syst Sci 2011, 120(4), 595-604.

This is paper presents an efficient algorithm, FDA2DMT (Free Decay Analysis for 2D Magnetotellurics (MT)), based on eigenmode approach to solve the relevant partial differential equation, for forward computation of two-dimensional (2D) responses. The main advantage of this approach lies in the fact that only a small subset of eigenvalues and corresponding eigenvectors are required for satisfactory results. This small subset (pre-specified number) of eigenmodes are obtained using shift and invert implementation of Implicitly Restarted Lanczos Method (IRLM). It has been established by experimentation that only 15-20% smallest eigenvalue and corresponding eigenvectors are sufficient to secure the acceptable accuracy. Once the single frequency response is computed using eigenmode approach, the responses for subsequent frequencies can be obtained in negligible time. Experiment design results for validation of FDA2DMT are presented by considering two synthetic models from COMMEMI report, Brewitt-Taylor and Weaver (1976) model and a field data based model from Garhwal Himalaya.

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001450   Khandekar M (NO, IPCC Climate Change, Toronto, Canada, Email: mkhandekar@rogers.com) : Monsoon 2010: progress and prognostics. J Geol Soc India 2010, 76(3), 205-7.

Climate change is currently the most important subject of concern agitating the minds of intellectuals all over the world. In India especially it plays a most important part on the livelihood of more than a billion people dependent on the seasonal variations in climate, more specially on the quantum of rainfall and its regularity. In the picturesque words of Prof. C.V. Raman, the noted Indian Nobel laureate, "the opening and closing of the sluice gates in the sky are the most important events in the calendar of the man who tills the earth in these areas". Yet in spite of studies by group of scientists all over the world, it has not been possible to predict the quantum of rainfall that the country is going to receive and the pattern it follows in its distribution. The subject is deserving of the closest of study especially by hydrogeologists who should watch from day to day the progress of the onset and movement of rain-bearing winds across the Indian continent. We have selected for this month's leading article a note by Madhav Khandekar, one of the world's leader in meteorology, with wide knowledge on climatology, and oceanography connected with IPCC 2007. The note presents a lucid summary of the current position of the progress of the monsoon and makes a strong case for pursuing studies aimed at gaining knowledge of this subject of great complexity and importance.

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001449   Khan Z A;Tewari R C (Directorate of Geology and Mining, Khanji Bhawan, Lucknow-226 011, Email: zahid26aug@yahoo.co.in ) : Paleochannel and paleohydrology of a Middle Siwalik (Pliocene) fluvial system, northern India. J Earth Syst Sci 2011, 120(3), 531-43.

Late Cenozoic fresh water molasses sediments (+6000 m thick) deposited all along the length of the Himalayan fore deep, form the Siwalik Supergroup. Reports the results of the paleodrainage and paleohydrology of the Middle Siwalik subgroup of rocks, deposited in non-marine basins adjacent to a rising mountain chain during Pliocene. Well-exposed sections of these rocks have provided adequate paleodrainage data for the reconstruction of paleochannel morphology and paleohydrological attributes of the Pliocene fluvial system. Cross-bedding data has been used as inputs to estimate bankfull channel depth and channel sinuosity of Pliocene rivers. Various empirical relationships of modern rivers were used to estimate other paleohydrological attributes such as channel width, sediment load parameter, annual discharge, and channel slope and flow velocity. Computed channel depth, channel slope and flow velocity are supported independently by recorded data of scour depth, cross-bedding variability and Chezy's equation. The estimates indicate that the Middle Siwalik sequence corresponds to a system of rivers, whose individual channels were about 400 m wide and 5.2-7.3 m deep; the river on an average had a low sinuous channel and flowed over a depositional surface sloping at the rate of 53 cm/km. The 700-km long Middle Siwalik (Pliocene) river drained an area of 42925 km² to the north-northeast, with a flow velocity of 164-284 cm/s, as it flowed generally south-southwest of the Himalayan Orogen. Bed-load was about 15% of the total load of this river, whose annual discharge was about 346-1170 m³/ s normally and rose to approximately 1854 m³/ s during periodic floods. The Froude number of 0.22 suggests that the water flows in the Pliocene river channels were tranquil, which in turn account for the profuse development of cross-bedded units in the sandstone. The estimated paleochannel parameters, bedding characteristics and the abundance of coarse elastics in the lithic fill are rather similar to the modern braided rivers of Canada and India such as South Saskatchewan and Gomti, respectively.

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001448   Karia S P;Pathak K N (NO, SV National Institute of Technology, Ichhanath, Surat, Gujarat-395 007, Email: kariasheetal@yahoo.co.in) : GPS based TEC measurements for a period august 2008-december 2009 near the northern crest of Indian equatorial ionospheric anomaly region. J Earth Syst Sci 2011, 120(5), 851-8.

Measurements of total electron content (TEC) have gained importance with increasing demand for the GPS-based navigation applications in trans-ionospheric communications. To study the variation in ionospheric TEC, we used the data obtained from GPS Ionospheric Scintillation and TEC monitoring (GISTM) system which is in operation at SVNIT, Surat, India (21.16°N, 72.78°E) located at the northern crest of equatorial anomaly region. The data collected (for the low sunspot activity period from August 2008-December 2009) were used to study the diurnal, monthly, seasonal semi-annual and annual variations of TEC at Surat. It was observed that the diurnal variation at the region reaches its maximum value between 13:00 and 16:00 1ST. The monthly average diurnal variations showed that the TEC maximizes during the equinox months followed by the winter months, and are lowest during the summer months. The ionospheric range delay to TEC for the primary GPS signal is 0.162 m per TECU. The diurnal variation in TEC shows a minimum to maximum variation of about 5 to 50 TECU (in current low sunspot activity periods). These TEC values correspond to range delay variations of about 1 to 9 m at Surat. These variations in the range delay will certainly increase in high sunspot activity periods. Detected TEC variations are also closely related to space weather'characterizing quantities such as solar wind and geomagnetic activity indices.

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001447   Kambhammettu B V N P;Allena P;King J P (Civil Engineering Dep, New Mexico State Univ, MSC 3CE, Box No. 30001, Las Cruces, NM-88003, USA, Email: phani@nmsu.edu) : Application and evaluation of universal kriging for optimal contouring of groundwater levels. J Earth Syst Sci 2011, 120(3), 413-22.

Deals with the application of universal kriging to interpolate water table elevations from their measurements at random locations. Geographic information system tools were used to generate the continuous surface of water table elevations for the Carlsbad area alluvial aquifer located to the southeast of New Mexico, USA. Water table elevations in the 38 monitoring wells that are common to 1996 and 2003 irrigation years follows normal distribution. A generalized MATLAB⊗ code was developed to generate omni-directional and directional semi-variograms (at 22.5° intervals). Low-order polynomials were used to model the trend as the water table profile exhibits a south-east gradient. Different theoretical semi-variogram models were tried to select the base semi-variogram for performing geostatistical interpolation. The contour maps of water table elevations exhibit significant decrease in the water table from 1996 to 2003. Statistical analysis performed on the estimated contours revealed that the decrease in water table is between 0.6 and 4.5 m at 90% confidence. The estimation variance contours show that the error in estimation was more than 8 m² in the west and south-west portions of the aquifer due to the absence of monitoring wells.

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001446   Kalpana M S;Patil D J;Dayal A M;Raju S V (NO, National Geophysical Research Institute (Council of Scientific and Ind, Uppal Road, Hyderabad-500 606, Email: kalpana@ngri.res.in) : Near surface manifestation of hydrocarbons in proterozic Bhima and Kaladgi basins: implications to hydrocarbon resource potential. J Geol Soc India 2010, 76(6), 548-56.

Reconnaissance surface geochemical survey for adsorbed soil gas analysis conducted in Proterozoic Bhima and Kaladgi Basins, have revealed occurrence of anomalous concentrations of light gaseous hydrocarbons i.e. C₁ to C₄ (CH₄, C₂H₆ C₃H₈ i-C₄H₁₀ and n-C₄H₁₀) in the near surface soils. The concentrations of C₁ and ΣC₂₊(C₂H₆+C₃H₈+ i-C₄H₁₀+ n-C₄H₁₀) in Bhima and Kaladgi Basins are in the range of 1-2594 ppb and 1 to 57 ppb and 1-1142 ppb and 1-490 ppb, respectively. The carbon isotopic data of adsorbed soil gas methane in few selected samples are in the range of -29.9 to -39%o (PDB). The evaluation of adsorbed soil gas data indicates that all the gas components are cogenetic and hydrocarbon ratios of C₁/(C₂+C₃) <60> 10 and C₃/C₁*1000 between 60-500 and 20-60 suggest that the adsorbed gases are derived from oil and gas-condensate zones. The carbon isotopic values of methane further support thermogenic origin of these migrated gases. The concentration distribution of C₁ and ΣC₂₊ in the study areas illustrate C₁ and ΣC₂₊ anomalies near Katamadevarhalli, Andola and Talikota in Bhima Basin and near Kaladgi, Lokapur and north of Mudhol in Kaladgi Basin. The hydrocarbon anomalies near the surface coincide with the favourable subsurface structural features and correlate with existing geochemical and geophysical data in these basins suggesting seepage related anomalies.

5 illus, 5 tables, 35 ref

001445   Jeelani G;Bhat N A;Shivanna K;Bhat M Y (Geology and Geophysics Dep, Kashmir Univ, Srinagar, Jammu & Kashmir-190 006) : Geochemical characterization of surface water and spring water in SE Kashmir valley, western Himalaya: implications to water-rock interaction. J Earth Syst Sci 2011, 120(5), 921-32.

Water samples from precipitation, glacier melt, snow melt, glacial lake, streams and karst springs were collected across SE of Kashmir Valley, to understand the hydrogeochemical processes governing the evolution of the water in a natural and non-industrial area of western Himalayas. The time series data on solute chemistry suggest that the hydrochernical processes controlling the chemistry of spring waters is more complex than the surface water. This is attributed to more time available for infiltrating water to interact with the diverse host lithology. Total dissolved solids (TDS), in general, increases with decrease in altitude. However, high TDS of some streams at higher altitudes and low TDS of some springs at lower-altitudes indicated contribution of high TDS waters from glacial lakes and low TDS waters from streams, respectively. The results show that some karst springs are recharged by surface water; Achabalnag by the Bringi stream and Andernag and Martandnag by the Liddar stream. Calcite dissolution, dedolomitization and silicate weathering were found to be the main processes controlling the chemistry of the spring waters and calcitc dissolution as the dominant process in controlling the chemistry of the surface waters. The spring waters were undersaturated with respect to calcite and dolomite in most of the seasons except in November, which is attributed to the replenishment of the CO₂ by recharging waters during most of the seasons.

9 illus, 9 tables, 58 ref

001444   Islam R;Ghosh S K;Vyshnavi S;Sundriyal Y P (NO, Wadia Institute of Himalayan Geology, Dehradun-248 001, Email: rislam@wihg.res.in) : Petrography, geochemistry and regional significance of crystalline klippen in the Garhwal Lesser Himalaya, India. J Earth Syst Sci 2011, 120(3), 489-501.

Uphalda gneisses (UG) is a crystalline klippe located near Srinagar in Garhwal Himalaya. These gneisses are compared with Debguru porphyroids (DP) (≈ Ramgarh group) of Garhwal Kumaun Himalaya and Baragaon mylonitic gneisses (BMG) of Himachal Himalaya. Petrographic study reveals that the deformation of UG was initiated at higher temperature (above 350°C) and continued till lowering of temperature and deformation led to the mylonitization. Geochemically, these granitic gneisses (UG, DP and BMG) exhibit similar composition. Features such as high molecular A/CNK value (<62>1), presence of normative corundum and absence of normative diopside, enhanced Rb/Sr, Rb/Zr ratios, enrichment of Th and containing rounded zircons support their crustally-derived S-type granitic nature. The linear plot in major oxides is interpreted in terms of fractional crystallization processes. Mantle normalized multi-element spider diagram of UG illustrates depletion of Ba, Nb, Sr, P and Ti and enrichment of Th and show similarities with DP and BMG. Similarities were observed in lithology, petrographic characters and chemical composition of UG, DP, BMG and Ulleri augen gneisses (Nepal). Comparison with the rocks of Higher Himalayan crystallines (≈ Vaikrita), suggests that these rocks (UG) are not transported from Higher Himalaya as understood earlier. This study however proposes that, these gneissic bodies represent an older basement occurring as a tectonic sliver which emplaced within the cover sequence as wedges at different structural levels. This is a regional phenomena observed throughout the Lesser Himalayan region.

9 illus, 1 table, 59 ref

001443   Islam M A (Geology Dep, Malaya Univ, 50603, Kuala Lumpur, Malaysia, Email: aminul_gm_ru@um.edu.my) : Petrophysical evaluation of subsurface reservoir sandstones of Bengal basin, Bangladesh. J Geol Soc India 2010, 76(6), 621-31.

The present study has been carried out for core and log based petrophysical evaluation of subsurface reservoir sandstones considering at least one well from each of the Kailas Tila, Titas, Bakhrabad and Shahbazpur gas fields of Bangladesh. Core analysis results show that average core porosity, permeability and pore throat values are 20%, 209 mD and 44020 A, respectively. These measured values support that the sandstone reservoirs are categorized as good quality reservoirs. Core porosity values usually exceed thin section porosity. Different cross-plots indicate that permeability is largely dependent on porosity. Permeability and porosity are also dependent on textural parameters that include size, shape, sorting and matrix of the reservoir sandstones. It reveals from both thin section study and different cross plots that diagenetic cements are the main controlling factors of the reservoirs. Quantitative determination of the volume of cements shows that cements have inverse correlation with porosity and permeability. Log based petrophysical parameters include shale volume, porosity, water and hydrocarbon saturation, permeability, moveability index and bulk volume of water. The average values of the mentioned parameters are 20%, 22%, 26%, 74%, 110 mD, 0.28 and 0.05, respectively. The most important parameters are porosity and permeability, which indicate that log porosity exceeds core porosity and log permeability significantly lags behind core permeability. The study also reveals that 23 gas zones covering total thickness of 385 m sandstones mostly posses good quality reservoirs except few moderate quality reservoirs.

6 illus, 3 tables, 28 ref

001442   Islam M A (Geology Dep, Malaya Univ, 50603 Kuala Lumpur, Malaysia, Email: aminul_gm_ru@edu.my) : Petrography and provenance of subsurface neogene sandstones of Bengal basin, Bangladesh. J Geol Soc India 2010, 76(5), 493-504.

This study deals with petrography and provenance of the Neogene reservoir sandstones encountered in the Kailas Tila, titas, Bakhrabad and Shahbazpur Gas Fields of Bengal Basin. Framework grains are sand-sized to silt-sized particles of mainly detrital origin. The most common detrital grains are quartz, feldspars, and rock fragments. Mica occurred as minor and non-opaque heavy minerals found as minor accessories. Among the main detrital framework grains, quartz constitutes 51-60%, feldspar 3-15%, lithic fragments 8-22%. Sandstones encountered in the studied wells have been classified as sublithic arenite, feldspathic arenite and lithic arenite in order of abundance. Different triangular plots reveal that the Neogene sandstones of the studied wells exhibit a quartzolithic composition, low feldspar, very low volcanic grains and abundant sedimentary and low grade metamorphic lithic clasts indicating that the sands were derived from quartzose recycled orogen province, such as a fold thrust province or a collision suture zone. This study suggests that either the eastern Himalayas or Indo-Burman Ranges might act as the source of the sandstones of the studied wells of the Bengal Basin.

8 illus, 3 tables, 35 ref

001441   Gupta H;Shashidhar D;Mallika K;Purnachandra Rao N;Srinagesh R D;Satyanarayana H V S;Saha S;Naik R T B (NO, National Geophysical Research Institute (CSIR), Uppal Road, Hyderabad-500 007, Email: harshg123gmail.com) : Short term earthquake forecasts at Koyna, India. J Geol Soc India 2011, 77(1), 5-11.

Earthquake activity is monitored in real time at the Koyna reservoir in western India, beginning from August 2005 and successful short term forecasts have been made of M - 4 earthquakes. The basis of these forecasts is the observation of nucleation that precedes such earthquakes. Here we report that a total of 29 earthquakes in the magnitude range of 3.5 to 5.1 occurred in the region during the period of August 2005 through May 2010. These earthquakes could broadly be put in three zones. Zone-A has been most active accounting for 18 earthquakes, while 5 earthquakes in Zone-B and 6 in Zone-C have occurred. Earthquakes in Zone-A are preceded by well defined nucleation, while it is not the case with zones B and C. This indicates the complexity of the earthquakes processes and the fact that even in a small seismically active area of only 20 km x 30 km earthquake forecast is difficult.

5 illus, 3 tables, 16 ref

001440   Guhathakurta P;Sreejith O P;Menon P A (India Meterological Dep, Shivajinagar, Pune-411 005, Email: pguhathakurta@rediffmail.com) : Impact of climate change on extreme rainfall events and flood risk in India. J Earth Syst Sci 2011, 120(3), 359-73.

The occurrence of exceptionally heavy rainfall events and associated flash floods in many areas during recent years motivate us to study long-term changes in extreme rainfall over India. The analysis of the frequency of rainy days, rain days and heavy rainfall days as well as one-day extreme rainfall and return period has been carried out in this study to observe the impact of climate change on extreme rainfall events and flood risk in India. The frequency of heavy rainfall events are decreasing in major parts of central and north India while they are increasing in peninsular, east and north east India. The study tries to bring out some of the interesting findings which are very useful for hydrological planning and disaster managements. Extreme rainfall and flood risk are increasing significantly in the country except some parts of central India.

12 illus, 21 ref

001439   Gowri V S;Ramesh R;Nammalwar P;Satheesh N; Rajkumar J;Banerjee K;Sesha Bamini N (NO, Institute of Ocean Management, Anna University, Chennai-600 025, Email: vsgowri59@gmail.com) : GIS approach in assessing the status of neritic water quality and petroleum hydrocarbons in Bay of Bengal (From Chennai to Nagapattinam, Tamil Nadu), India. Int J Geomatics Geosci 2012, 3(1), 249-58.

Neritic coastal water samples, collected onboard in Ocean Research Vessel (Sagar Purvi, NIOT) at a depth of 15m from the shore in August, 2010 at 15 coastal stations (opposite to the river mouths, fish landing centres and nuclear power station) stretching from Chennai to Nagapattinam, Bay of Bengal, Tamilnadu, were analysed for water quality parameters to find the impact of anthropogenic activities/sea based activities on the coastal water. Significant contribution from the present study reveals that the dissolved oxygen content in the neritic waters ranged from 1mg/l to 5.2mg/l which shows a decreasing trend from north to south direction. Kaliveli coastal water is highly polluted with petroleum hydrocarbon (1772.50ug/l) followed by Ponnaiyar river region, Cooum river region and Puducherry coastal area and the wind direction was found to be mostly towards Southwest and West. The higher concentration of petroleum hydrocarbons at Kaliveli coastal area gives a great concern because it is an important bird area, an important point for winter migrants like Storks (Ciconia ciconia) and crested pochards. There is a lack of awareness about ecological importance and protection of such wetlands among local people. The study necessitates continuous monitoring and modeling of petroleum hydrocarbons along with prevailing hydrodynamic conditions in the coastal water which will be useful in improving the health status of marine environment, nearby wetland and associated biota.

6 illus, 4 tables, 16 ref

001438   Ghazi S;Mountney N P (Institute of Geology, Punjab Univ, Quaid-i-Azam Campus, Lahore-54590, Pakistan, Email: ghazigeo@yahoo.com) : Subsurface lithofacies analysis of the fluvial early permian Warchha sandstone, Potwar basin, Pakistan. J Geol Soc India 2010, 76(5), 505-17.

The Early Permian Warchha Sandstone is well preserved in subsurface in the Potwar Basin and the Punjab Plain of Pakistan. However, this succession is only exposed in the Salt Range, and within this region, only a modest number of the many outcrops are of sufficient quality to enable the preparation of lateral and vertical log profiles. From the subsurface, data from five wells drilled in the Salt Range and Potwar Basin have been analysed. Although they are of restricted coverage, these subsurface data - which take the form of gamma ray logs and well cuttings - provide a valuable addition to the outcrop dataset of the Warchha Sandstone as they provide useful information about vertical textural changes, type and thickness of bedding and the nature of sandbody contacts with underlying strata. Overall, the Warchha Sandstone succession is composed of repeated fining-upwards cycles indicative of a meandering fluvial succession. Sub-components of each cycle are themselves classified into six subsurface sedimentary facies. Through comparison with outcropping parts of the succession, the origin and significance of these subsurface facies can be related to specific architectural elements within the meandering fluvial system responsible for generating the Warchha Sandstone succession.

5 illus, 1 table, 32 ref

001437   Gajbhiye S;Sharma S K (Water Resources Development and Management Dep, Indian Institute of Technology, Uttarakhand, Email: gajbhiyesarita@gmail.com) : Land use and land cover change detection of Indra river watershed through remote sensing using multi-temporal satellite data. Int J Geomatics Geosci 2012, 3(1), 89-96.

Land use and land cover is an important component in understanding the interactions of the human activities with the environment and thus it is necessary to be able to simulate changes. Empirical observation revealed a change in land use land cover classification in Indra river watershed located in Hoshangabad district (M.P). In this paper an attempt is made to study the changes in land use and land cover in Indra river watershed over 14 years period. The study has been done through remote sensing approach using Land Sat imageries of October 1992 and November 2006. The land use land cover classification was performed based on Satellite imageries. GIS software is used to prepare the thematic maps. The study has brought to light that forest area that occupied about 15.01 per cent of the study area in 1992 has increased to 25.57 per cent in 2006. Built up area, water body and Waste land also have experienced change. Farm land (Agricultural land/open land) has decreased from 84.16 per cent to 68.40 per cent of the total area. Proper land use planning is essential for a sustainable development of Indra nadi watershed.

4 illus, 3 tables, 23 ref

001436   Fareeduddin;Gupta S;Golani P R;Kirmani I R; Suresh Chander (NO, Geological Survey of India, PPOD Div, RSAS Wing, Kumarraswamy Layout, Bangalore-560 078, Email: fareedromani@hotmail.com) : Tourmaline as metallogenic indicator: examples from paleo-proterozoic Pb-Zn and Cu-Au deposits of Rajasthan. J Geol Soc India 2010, 76(3), 215-43.

Petrology and mineral chemistry of ten types of tourmalines from Pb-Zn bearing strata-bound exhalative deposits and Cu-Au-Fe deposits, presumably of lOCG-type, from Rajasthan are presented. The Pb-Zn deposits studied include Agucha, Kayar and Dariba areas in central Rajasthan, each of which is widely separated in space and occurs in isolated but coeval basins within the Archaean basement. The Cu-Au deposits include Ghagri, Bada Talav, Dugocha and Bhukia areas in southeast Rajasthan. The syngenetic Pb-Zn type and the epigenetic Cu-Au-Fe type of deposits are formed during the initial phase of Paleoproterozoic Aravalli Basin evolution with dominant deposition of shelf facies pelite-carbonate sequence of Debari Group. The post-depositional tectono-metamorphic history of the host rocks of Pb-Zn type and Cu-Au type deposits differ significantly with the former deposits showing higher metamorphic impress (amphibolite to lower granulite facies) than the latter (green schist facies). This study suggests that tourmalines on individual deposit scale exhibit both similarities and differences in optical and chemical features that are in accordance to their bulk host mineral assemblages. But on individual belt-scale, despite significant differences in the post-depositional metamorphic alterations, there is an overall chemical similarity of tourmalines that suggests prevalence of similar hydrothermal conditions during the formation of the tourmalines of individual deposits in each of the Pb-Zn and Cu-Au belts. In many of the discriminant diagrams using the critical elements, the tourmalines of these two belts maintain a distinct identity and assert their role as metal-type indicator in contemporaneous (Paleoproterozoic) deposits formed in different hydrothermal conditions. This study also tests the reported role of tetrahedral alumina (Al^iv) and X-site vacancies (X) in the tourmaline in indicating the grade of metamorphism of the host rocks. Whereas this study confirms the assertions regarding the co-variance of Al^iv with respect to the grade of metamorphism in calcareous and metapelitic sediments, the same assertions could not be made in. The latter is attributed to the diffusion of Na+ in the tourmaline structure from the abundantly available Na-rich host rocks (albitites) in a post-ore formation event.

12 illus, 7 tables, 47 ref

001435   Dutta S;Roy S (NO, Gadadharpur Bazar Junior High School, Birbhum-731 234, Email: duttashyamal1987@gmail.com) : Determination of erosion surfaces and stages of evolution of Sangra drainage basin in Giridih district, Jharkhand, India. Int J Geomatics Geosci 2012, 3(1), 63-73.

Major emphasis in geomorphology over the past several decades has been on the development of quantitative physiographic methods to describe the evolution and behavior of surface drainage networks. The quantitative analysis of morphometric parameters is found to be of immense utility in river basin evaluation. The influence of drainage morphometry is very significant in understanding the landform processes, soil physical properties and erosional characteristics. Drainage characteristics of many river basins and sub-basins in different parts of the globe have been studied using conventional methods. Modern statistical analysis and Geographical Information System (GIS) techniques are now-a-day used for assessing various terrain and morphometric parameters of the drainage basins as they provide a flexible environment and a powerful tool for the manipulation and analysis of spatial information. In the study, stream number, order, frequency, density and bifurcation ratio are derived and tabulated on the basis of areal and linear properties of drainage channels using GIS based on drainage lines of Sangra Drainage Basin of Giridih, Jharkhand as represented over the topographical map (R.F. 1:50,000). Area-altitudinal relationship also be assessed in this work to identify the erosional surfaces as well as stage of evolution. Besides, an attempt to analyze and establish relationship between the depended and independent variables through Principal component analysis to identify the major morphometric parameters which has a significant role in the erosional landforms of this drainage basin.

7 illus, 7 tables, 14 ref

001434   Durand F;Papa F;Rahman A;Bala S K (NO, , LEGOS, IRD, Noumea, New-Caledonia, Email: fabien.durand@ird.fr) : Impact of Ganges-Brahmaputra interannual discharge variations on Bay of Bengal salinity and temperature during 1992-1999 period. J Earth Syst Sci 2011, 120(5), 859-72.

This study investigates the impact of monthly Ganges-Brahmaputra river discharge variations on Bay of Bengal salinity and temperature during the period 1992-1999. The Ganges-Brahmaputra river discharge is characterized by a well-defined seasonal cycle with strong inter annual variations. The highest/lowest yearly peak discharge occurs in summer 1998/summer 1992, with 1998 value amounting to twice that of 1992. This river discharge is then used to force an ocean general circulation model. Our main result is that the impact of these rivers on the variability of Bay of Bengal sea surface salinity is strong in the northern part, with excess run-off forcing fresh anomalies, and vice versa. Most of the years, the influence of the interannual variability of river discharge on the Bay salinity does not extend south of <126>10°N. This stands in contrast with the available observations and is probably linked to the relatively coarse resolution of our model. However, the extreme discharge anomaly of 1998 is exported through the southern boundary of the Bay and penetrates the south-eastern Arabian Sea a few months after the discharge peak. In response to the discharge anomalies, the model simulates significant mixed-layer temperature anomalies in the northern Bay of Bengal. This has the potential to influence the climate of the area. From our conclusions, it appears necessary to use a numerical model with higher resolution (both on the horizontal and vertical) to quantitatively investigate the upper Bay of Bengal salinity structure.

9 illus, 35 ref

001433   Dinesh A C;Maran M;Shareef N M; Chandrasekaraiah K C;Jayaprakash C (Geological Survey of India, Marine & Coastal Survey Div, Mangalore-575 001, Email: acdinesh@rediffmail.com) : Observations on the reported incidence of micro-diamonds in the beach sands of the Kanyakumari coast, Tamil Nadu. J Geol Soc India 2010, 76(6), 987-88.

Fourteen beach samples were collected between Uvary in the northeast and Kanyakumari in the southwest within a coastal stretch of 50 km were studied to confirm the reported occurrence of micro-diamonds in Pulimankulam beach sands. The XRD results suggest that grains with brilliant luster are mainly zircon and the presence of micro-diamond could not be ascertained in any of the samples. The fusion of samples with NaOH and further digestion in acid did not leave any residue. This also confirms absence of any non-silicate mineral in the samples.

2 illus, 1 table, 1 ref

001432   Dasgupta N;Pal T;Sen J;Ghosh T (Geology Dep, Presidency Univ, 86/1 College Street, Kolkata-700 073, Email: neelakdg@gmail.com) : Characteristics of pegmatoidal granite exposed near Bayalan, Ajmer district, Rajasthan. J Earth Syst Sci 2011, 120(4), 617-26.

The study involves the characterization of pegmatoidal granite, southeast of Beawar, Ajmer district, Rajasthan. Earlier researchers had described this granite as part of the BGC, basement to the Bhim Group of the Delhi Super Group rocks. However, the present study indicates that it is younger than the rocks of Bhim Group of South Delhi Fold Belt, into which it is intrusive. The intrusion is structurally controlled and the outcrop pattern is phacolithic. The granite had intruded post-D₂ deformation of the Delhi orogeny along the axial planes of D₂ folds. The intrusion has also resulted in the formation of a contact aureole about the calc gneisses.

9 illus, 1 table, 20 ref

001431   Das B;Mondal M;Das A (NO, West Bengal State Council of Science and Technology, Government of Wes, West Bengal, Email: milanmondal2055@gmail.com) : Monitoring of bank line erosion of river Ganga, Malda district, and West Bengal: using RS and GIS compiled with statistical techniques. Int J Geomatics Geosci 2012, 3(1), 239-48.

Creation of regional imbalance, inequalities and differentiation in India, starts with the physiographic element and ends with economic, and socio-cultural parameters of the inhabitants/population. An attempt has been made to analyze and report the river bank erosion due to morphometric changes of the river Ganga, Malda district making thus portion a high risk zone. For that physical process namely river bank erosion may affect the economic and socio-cultural aspects and creates drastic change over the period. Continuous monitoring and maintenance of these flood induced river bank management are necessary for the beneficial result. The distressed people demand a holistic and positive approach to tackle the problem.

4 illus, 4 tables, 14 ref

001430   Chidambaram S;Karmegam U;Sasidhar P;Prasanna M V;Manivannan R;Arunachalam S;Manikandan S;Anandhan P (Earth Sciences Dep, Annamalai Univ, Annamalai Nagar-608 002, Email: megapriyan@gmail.com) : Significance of saturation index of certain clay minerals in shallow coastal groundwater, in and around Kalpakkam, Tamil Nadu, India. J Earth Syst Sci 2011, 120(5), 897-909.

The saturation index of clay minerals like Gibbsite, Kaolinite, Illite, Montmorillonite and Chlorite in groundwater were studied in detail by collecting 29 groundwater samples from the shallow coastal aquifers in and around Kalpakkam. The samples collected were analysed for major cations, anions and trace elements by using standard procedures. The study reveals that pH has a significant role in the saturation index (SI) of minerals. It also shows that the relationship of electrical conductivity to the SI of these minerals is not significant than that of the ionic strength, log pCO₂ values, and alumina silica ratio have significant relation to the SI of these clay minerals. The SI of these clay minerals was spatially distributed to identify the areas of higher SI. Silica has good correlation to SI of Kaolinite, Gibbsite and Montmorillonite and Al has good correlation to SI of all the minerals except to that of Chlorite.

11 illus, 2 tables, 40 ref

001429   Chandrakala K;Pandey O P;Mall D M;Sarkar D (NO, National Geophysical Research Institute (Council of Scientific & Indus, Uppal Road, Hyderabad-500 007, Email: chndrbhat@yahoo.com) : Seismic signatures of a proterozoic thermal plume below south-western part of the Cuddapah basin, Dharwar craton. J Geol Soc India 2010, 76(6), 565-72.

Origin and evolutionary history of the Cuddapah Basin in SE India has remained a subject of considerable speculation whether it was evolved through vertical tectonic movements, extentional stretching or even cometary impact. Based on detailed seismic and other geophysical studies (Gravity, magnetotelluric and heat flow), we have delineated signatures of a possible deep seated mantle plume below southwestern part of the Cuddapah Basin, which may have been responsible for the 1.1 Ga kimberlitic magmatism in the eastern part of the Dharwar craton (EDC). The thermal anomaly associated with this mantle plume appears to have resulted into 15-20 km thick magmatic underplating (Vp: 7.10 -7.30 km/s; density 3.07-3.16 g/cm³) below the Parnapalle region of the southwestern Cuddapah Basin, which also coincides with the high gravity and high conductivity anomaly. The massive underplating led to thickening of the crust to about 40 - 44 km below southwestern part of the Cuddapah Basin, compared to about 34± 2 km in the surrounding regions of EDC, indicating thermal restructuring of the crust / mantle boundary. This plume, which was apparently active in an area of about 500 km radius, may have also affected the Closepet granitic region, which is <126>100 km west of Cuddapah Basin.

6 illus, 29 ref

001428   Chandra Singh M;Kundal P;Kushwaha R A S (Geology Dep, Imphal College, Imphal-795 001, Email: m_2008chand@rediffmail.com) : Ichnology of Bhuban and Boka bil formations, oligocene-miocene deposits of Manipur western hill, Northeast India. J Geol Soc India 2010, 76(6), 573-86.

Oligocene-Miocene deposits of Bhuban and Boka Bil Formations, Surma Group, Manipur Western Hill consist of well preserved ichnofossil assemblages. These formations are represented by eight lithofacies such as Massive sandstone (Sm), Rippled marked argillaceous sandstone (Sr), Wavy laminated sandstone-siltstone-silty shale (Sw), Laminated shale (Fl), Massive mudstone (Fm), Trough cross-bedded sandstone (St), Lenticular laminated sandstone-siltstone-silty shale (Sll) and Laminated to massive sandstone-siltstone (Ssc). Fifteen ichnospecies were identified, which further categories into Skolithos, Cruziana, and Skolithos/Cruziana ichnofacies. Overall distribution pattern and behavioural nature of the ichnoassemblage and sedimentological attributes suggests that the sediments of Bhuban and Boka Bil Formations were deposited under frequent fluctuating sea level, moderate to strong energy condition, subtidal to lower intertidal environment, rich in organic nutrients.

5 illus, 2 tables, 81 ref

001427   Chakraborty S;Jana B N;Bhattacharya S K; Robertson I (NO, Indian Institute of Tropical Meteorology, Dr. HomiBhabha Road, Pune-411 008, Email: supriyoc@gmail.com) : Carbon isotopic composition of fossil leaves from the early cretaceous sediments of western India. J Earth Syst Sci 2011, 120(4), 703-11.

Stable carbon isotope analysis of fossil leaves from the Bhuj Formation, western India was carried out to infer the prevailing environmental conditions. Compression fossil leaves such as Pachypteris indica, Otozamite kachchhensis, Brachyphyllum royii and Dictyozamites sp. were recovered from three sedimentary successions of the Bhuj Formation, Early Cretaceous in age. A chronology was established based on faunal assemblage and palyno-stratigraphy and further constrained by carbon isotope stratigraphy. The three sampling sites were the Karawadi river bank near Dharesi; the Chawad river bank near Mathal; and the Pur river section near Trambau village in Gujarat. The Dharesi sample was also analyzed to investigate intra-leaf δ¹³ C variability. The mean δ¹³ C of the leaf was -24.6 ± 0.4%o which implied negligible systematic change along the leaf axis. The Mathal sample was fragmented in nature and showed considerable variation in carbon isotopic composition. The Trambau sample considered to be the oldest, dating to the middle of Aptian (ca. 116 Ma), shows the most depleted value in δ¹³C among all of them. The overall δ¹³C trend ranging from mid Aptian (ca. 116 Ma) to early Albian (ca. 110 Ma) shows a progressive increase in δ¹³C from -26.8 to -20.5%o. Based on these measurements the carbon isotopic composition of atmospheric carbon dioxide of the Aptian-Albian period is estimated to be between -7.4 and - 1.7%o. The ratio of the partial pressure of carbon dioxide in leaf to that of the ambient atmosphere calculated based on a model is estimated to be similar to that of the modern plants. This indicates that the Early-Cretaceous plants adapted to the prevailing high carbon dioxide regime by increasing their photosynthetic uptake.

5 illus, 2 tables, 53 ref

001426   Chakrabarty A;Sen A K (Earth Sceinces Dep, IIT Roorkee, Roorkee-247 667, Email: senakfes@iitr.ernet.in) : Enigmatic association of the carbonatite and alkali-pyroxenite along the northern shear zone, Purulia, West Bengal: a saga of primary magmatic carbonatite. J Geol Soc India 2010, 76(4), 403-13.

The Purulia carbonatite, 'carbonatite'-'alkali-pyroxenite'-'apatite-magnetite rock' association, is located at Beldih area of Purulia district, West Bengal and falls within the 100 km long Northern Shear Zone (NSZ). Published literature suggests that the Purulia carbonatite was formed by the process of liquid immiscibility from under-saturated silicate parent magma. However, no silica under-saturated rocks like ijolite, nepheline-syenite etc. is known from the area. The trace element geochemistry (Ba/La, Nb/Th, Nb/Pb and Y/Ce ratios in the present study) also does not support this view. Present study indicates that the Purulia carbonatite is enriched in ΣREE and incompatible elements but the carbonatite is also poorer in Nb, Th and Pb compared to the world average of calicocarbonatites. The lower value of Nb is characteristics of carbo(hydro)thermal carbonatite where carbonatite is associated with alkali-pyroxenite and suggests probable origin of the carbonatite as carbothermal residua evolved from an unknown parentage. However, the field, petrographic and geochemical data indicate the genesis of this carbonatite from a primary carbonatitic magma of mantle decent. The ⁸⁷Sr/⁸⁶ Sr ratio of the carbonatite and apatite separated from the carbonatite (<126>0.703) implies primary magmatic derivation of the Purulia carbonatite. Close similarity of the apatite of the apatite-magnetite rock with the mantle apatite (of type Apatite B) indicates that they are also of primary magmatic origin. The present work portrays a unique example where primary magmatic carbonatite is associated with the alkali-pyroxenite.

5 illus, 3 tables, 44 ref

001425   Chakrabarty A;Pruseth K L;Sen A K (Earth Sciences Dep, Institute Instrumentation Centre, IIT Roorkee, Roorkee-247 667, Email: senakfes@iitr.ernet.in) : First report of eudialyte ocurrence from the Sushina hill region, Purulia district, West Bengal. J Geol Soc India 2011, 77(1), 12-16.

Eudialyte is a group of hydrated silicate minerals essentially consisting of Na and Zr with a very complex crystal structure, and generally associated with alkaline rocks. The complexity of the eudialyte structure can be understood from the fact that Na alone exist in five distinct sites and extensive solid solubility can occur in almost all cation sites, sometimes one element occupying multiple sites to the extent of exclusion of other elements. Structurally, eudialyte can be represented as Na₁₅[M₁]₆[M₂]₃Zr₃[M₃](Si_{2 5}O₇₃)(O,OH,H₂O)₃X₂ (Johnsen and Grice, 1999), where M₁ and M₂ sites are occupied by Ca, Mn and Fe, M₃ by Nb and X by OH, Cl and F. In addition, cations like Al, Hf, W, Ta, Sr, Ba and various REEs get incorporated into the eudialyte structure by substitution, and additional site vacancies even may develop in order to maintain electrical neutrality. Eudialyte, approximately of the composition Na₉Ca₈Mn₃Nb(Zr,Ce)₃Si₂₅O₇₃(OH)₂ , has hydrothermally replaced albite in the nepheline syenite gneiss exposed south of the Sushina hill of Purulia district, West Bengal. The eudialyte contains =2.25 atom % Zr and 0.75 atom % Nb. In addition to eudialyte in nepheline syenite, an unknown Na-Zr silicate (NZS) has also replaced the albite crystals. The NZS contains ≈ 7 atom % Zr with a possible empirical formula of Na₁₂Zr₁₁Si₃₆O₉₅(OH)₁₀. Surface exposures of these rocks are limited at Sushina hill, yet a detailed and systematic investigation on this enigmatic rock is warranted for they may turn out to be a resource for Zr.

3 illus, 1 table, 15 ref

001424   Brindha K;Elango L;Nair R N (Geology Dep, Anna Univ, Chennai-600 025, Email: elango34@hotmail.com) : Spatial and temporal variation of uranium in a shallow weathered rock aquifer in Southern India. J Earth Syst Sci 2011, 120(5), 911-20.

Uranium occurs naturally in groundwater and surface water. The objective of this study is to understand the causes for the occurrence of uranium and its spatio-temporal variation in groundwater in a part of Nalgonda district, Andhra Pradesh, south India. Uranium deposits occur in the southeastern part of this area. Groundwater samples were collected from 44 wells every two months from March 2008 to January 2009. The samples were analyzed for pH, ORP and uranium concentration. The uranium concentration in groundwater varies from 0.2 ppb to a maximum of 68 ppb with a mean of 18.5 ppb. About 21.6% of the samples were above the drinking water limit of 30 ppb set by USEPA. The uranium concentration varied with fluctuation in groundwater level, pH and ORP. Uranium concentration in groundwater changes depending on lithology, degree of weathering and rainfall recharge.

12 illus, 2 tables, 30 ref

001423   Bijeesh K V (NO, Codex Remote Ciencias Espaciais e Imagens Digitais, Porto Alegre, Brazil, Email: bijeesh@codexremote.com.bro) : Three decadal monitoring of mountain glaciers in Ecuador - a case study on ENSO impact on Andean glaciers: a remote sensing perspective. Int J Geomatics Geosci 2012, 3(1), 269-84.

Describes the application of remote sensing in monitoring mountain glaciers in the Ecuadorean Andes during the past three decades using EO-1 ALI, Landsat MSS, TM and ETM+ images. An attempt to correlate the El Ni¤o - Southern Oscillation (ENSO) phenomenon with the glacier fluctuations in Ecuadorian Andes is done in this research. Precipitation data from various gauging stations in capital Quito, Napo and surrounding areas were utilized in this study and tried to correlate the precipitation data with ENSO variables. A lag of 1 to 3 months in zonal mean tropical anomalies relative to equatorial east pacific SSTs is proven from the mass balance changes. The changes in these mountain ice caps were believed to have some connections with the global warming scenarios and local factors such as volcanic activity and surface air temperature values. Different ice caps in the two different cordilleras showed different response rates in mass balance changes. One of the greatest advantage of using remote sensing data in multitemporal glacier monitoring is the fact that a large number of glaciers can be studied within a limited time period with minimum cost.

5 illus, 2 tables, 52 ref

001422   Bhonde U;Desai B G (NO, , Pavandham Soceity, Samta Road, Subhanpura, Vadodara-390 023, Email: uabhonde@yahoo.com) : Discontinuity surfaces and event stratigraphy of Okha shell limestone member: implications for Holocene sea level changes, western India. J Earth Syst Sci 2011, 120(4), 723-34.

The Okha Shell Limestone Member of Chaya Formation is the coarse grained, shell rich deposit commonly recognized as the beach rocks. It has been age bracketed between Late Pleistocene and Holocene. Late Quaternary sea level changes have been studied with beach rocks along the Saurashtra coastal region. The present study has been carried out in the Okhamandal area of the Saurashtra peninsula especially on the Okha Shell Limestone Member as exposed at various locations along the coast from north to south. Temporal and spatial correlations of the observations have revealed three events in the Okha Shell Limestone Member of Chaya Formation that are correlated laterally. The events show depositional breaks represented by discontinuity surfaces, the taphofacies varieties and ichnological variations. The present study in the context of available geochrnological data of the region suggests a prominent depositional break representing low sea level stand (regression) during an Early Holpcene during the deposition of Okha Shell Limestone Member.

3 illus, 4 tables, 36 ref

001421   Bhattacharya S K (Geography and Applied Geography Dep, North Bengal University, Darjeeling-734 013, Email: skbhatt2002@yahoo.co.in) : Landslide disaster perception of the AILA cyclone in the Darjeeling town, West Bengal, India. Int J Geomatics Geosci 2012, 3(1), 13-29.

Heavy downpour of 465 mm within 48 hours (which is equivalent to nearly 12 days' rainfall in the rainiest month i.e. July) was the cause for several destructive landslides claiming 7 lives and huge property in the Darjeeling town on 26th and 27th May, 2009 triggered by the cyclone Aila. The present paper deals with the detailed investigation of two such most devastating landslides occurred at Frimal Village and Haridas Hatta in the Darjeeling town. In the Frimal Village, landslide reoccurred five times on a single spot within a period of 18 hours completely demolishing 22 houses below and three dunny (safety) tanks within the slide itself. No casualty was recorded except huge loss of property. But in the Haridas Hatta, landslide occurred only one time with high intensity partially damaging a house at the lower level and claimed seven lives. It is found that reckless construction of multi-storied buildings and their pressure, unmanaged building and community outlets, alteration of the natural setup of the soil by frequent digging for funeral purpose contributed the physical changes in the slope character. These changes being associated with scanty vegetation cover on the soil surface and poorly maintained plants of the tea garden incapable of holding soil on the steep slopes were the causes of such devastations following heavy gush of rain by the cyclone Aila.

13 illus, 4 tables, 27 ref

001420   Bhattacharya D K;Mukherjee D;Barla V C (Post Graduate Geology Dep, Ranchi Univ, Ranchi-834 008, Email: dkbprofru78@gmail.com) : Komatiite within chhotanagpur gneissic complex at Semra, Palamau district, Jharkhand: petrological and geochemical fingerprints. J Geol Soc India 2010, 76(6), 589-606.

Komatiite near Semra village, southwest of Daltonganj in Palamau District of Jharkhand, occurs within tremolite actinolite schist of ultramafic parentage. The fragmented olivine phenocrysts show mutually parallel as well as angular alignment, representing relict spinifex texture. Mineralogically the Semra ultramafic is lehrzolite in composition. The cumulates lack visible deformation suggesting original magmatic crystallization of these ultramafic rocks. The present occurrence of Spinifex Textured Peridotitic Komatiite (STPK) in Chhotanagpur Gneissic Complex (CGC) at northwestern part of Eastern Indian Shield is of great significance as it opens up a possibility of the presence of Archaean rock in CGC, which is yet to be established. These ultramafics are geochemically characterised by distinctive high MgO, Ni, Cr and poor in alkali, TiO₂, Ba, Cs, Rb. Nb, Hf and Y contents. It has low abundance of incompatible elements and is LREE depleted [(La/Yb)_n = 0.74 -1.07] with enriched flat HREE profile, representing chondrite like composition. This shows diagnostic convex upward REE profile. All these together with relict but distinct spinifex texture confirm the komatiitic character of Semra ultramafic. The chemical data plots for ultramafics confine to komatiite field in discriminate diagrams. The Mg<35> (<62>74) of the Semra ultramafics are comparable to primitive upper mantle Mg<35> (89.8) and high enough for rocks derived from ultramagnesian liquid of the mantle derived source. Considerably high Zr concentration in Semra ultramafic is attributed to Zr-enriched mantle source. Geochemically Semra ultramafics is comparable with "Al-undepleted" Munro type komatiites. Depleted incompatible trace elements also point towards Al-undepleted nature for the investigated ultramafics, which are characterised by distinctive low SiO₂, content in comparison to many well known komatiites of the world. The low K₂O content indicate plume related magmatism for its generation. Tectonic setting of this STPK with distinctive cumulus nature is suggestive of its emplacement in an extensional tectonic regime.

7 illus, 3 tables, 95 ref

001419   Banakar V K (NO, National Institute of Oceanography (CSIR), Dona Paula, Goa-403 004, Email: banakar@nio.org) : Deep-sea ferromanganese deposits and their resource potential for India. J Indian Inst Sci 2010, 90(4), 535-41.

Due to rapidly depleting land-based mineral resources oceanic mineral deposits gain greater significance. Ferromanganese deposits on the seabed (nodules) and seamounts (crusts) known for the enrichment of several transition metals were discovered during pioneering expeditions of H. M. S. Challenger during 1872-76. The metal contents in these deposits show large variations from basin to basin. For India, the Cu and Ni (<126>1% each) in nodules and Co (<126>0.7%) and Pt (<126>0.5 ppm) in seamount crusts recovered from the Indian Ocean are important. The hydrogenous crusts are not only important as economically valuable deposits of Co and Pt, but also are potential paleoceanographic repositories. Ferromanganese nodule exploration by India began in 1981 and concluded with recognition by the International Seabed Authority as a Pioneer Investor in 1987. This exploration license provides India with exclusive exploration rights over an area of 150,000 km² (Pioneer Area) in the Central Indian Ocean. Nearly 700 million tonnes of nodule resources are estimated in this mine site, which are expected to contain around 14 million tonnes of combined Cu and Ni metals valued approximately over Rs. 1000 billion at current average market rate. Quantitative resource evaluation for seamount ferromanganese crusts is not yet available due to limited exploratory work. However, a promising area of Co-Pt enriched ferromanganese crust occurrence has been discovered on the Afanasiy-Nikitin Seamounts in the Eastern Equatorial Indian Ocean by NIO scientists, which contains Co upto 0.9% and Pt upto 1 ppm.

5 illus, 27 ref

001418   Bakkiaraj D;Nagendra R;Nagarajan R; Armstrong-Altrin J S (Geology Dep, Anna Univ, Chennai-600 025, Email: bakkiaraj81@gmail.com) : Geochemistry of sandstones from the upper cretaceous Sillakkudi formation, cauvery basin, Southern India: implication for provenance. J Geol Soc India 2010, 76(5), 453-67.

Major, trace and rare earth elements (REE) composition of sandstones from the Upper Cretaceous Sillakkudi Formation, Ariyalur Group, Cauvery Basin were studied to decipher their weathering and provenance history. Texturally, these sandstones are immature, poorly sorted and grain supported. Abundance of feldspars especially, plagioclase indicates rapid deposition of sediments from a nearby source rocks. Using the geochemical classification diagram the Sillakkudi sandstones are classified as fe-sand, quartz arenite, litharenite, sub-litharenite, sub-arkose, arkose, and wacke types, which is also supported by the petrography study. The transition trace elements like Co, Ni, and V are higher in the Sillakkudi sandstones than upper continental crust (UCC) values. However, the Sillakkudi sandstones are lower in Cr (mean <126>21) content than average UCC value (<126> 35). The poor correlation between Cr and Ni (r = 0.08, number of samples n = 20) imply that these sandstones were derived from felsic source rocks. Similarly, the Eu/Eu* (0.35-1.73), La/ Sc (1.93-9.36), Th/Sc (0.41-6.57), Th/Co (0.14-5.01), Th/Cr (0.23-2.94), and Cr/Th (0.34-4.28) ratios support a felsic source for the Sillakkudi sandstones. The significant enrichment of Zr, Hf, and Th in fe-sand, sub-arkose and litharenite could be related to the presence of heavy minerals, especially zircon. However, the zircon geochemistry did not affect the REE distribution and its patterns in the Sillakkudi sandstones. The Chondrite normalized REE patterns of Sillakkudi sandstones are characterized by relatively flat HREE (Gd/Yb_CN = <126> 0.73-2.41; subscript _CN refers to chondrite normalized value), enriched LREE (La/Sm_CN = <126> 3.39-5.82) and negative Eu anomaly (mean value Eu/Eu* = 0.80). The Gd/Yb_CN ratios (-0.73-2.50) are less than 2.5, which suggest that these Sillakkudi sandstones were derived from the less HREE depleted source rocks. The comparison of REE patterns and its Eu anomalies to the source rocks reveals that the Sillakkudi sandstones received a major contribution of sediments from Dharwar craton.

11 illus, 3 tables, 90 ref