004621   Sarma B S P;Rao M V R K (National Geophysical Research Institute, , Uppal Road, Hyderabad-500 007, Email: sarmabsp@yahoo.co.in) : Basement structure of Godavari basin, India - geophysical modelling. Curr Sci 2005, 88(7), 1172-5.

In the study an attempt has been made to obtain a comprehensive picture of the basement structure through the gravity and magnetic profiles across the Godavari basin, in southern India. The available gravity and magnetic profiles are modelled, jointly, by assuming geologically feasible basement structure and sedimentary columns. The basement picture of the Godavari basin comprising the Proterozoic sediments and the Gondwana sediments, appears to be an asymmetric basin, but the Gondwana basin seems to be a symmetric graben. The contact between the Gondwana sediments and the northeastern Proterozoic sediments is a steep fault, which is the master fault. The thickness of the sediments in the middle of the Godavari basin is around 7 km, which might include some thickness of Proterozoic sediments also. Some low-density granites may also constitute this thick column. Modelling suggests that the basement rocks abutting the Proterozoic sediments on either side of the basin, are of higher density and susceptibility than the granitoids. These data do not manifest any basic bodies in the sediments. It is likely that the main graben formation is after the deposition of Proterozoic sediments on either side of the Gond-wana sediments.

3 illus, 1 table, 15 ref

004620   Sabanayagam R;Jayakumar D (Geol Dep, Presidency Coll, Chennai) : Fluid inclusions from Charnockites of Toppur, Salem-Dharmapuri district, Tamil Nadu, South India. Indian Mineralogist 2005, 39(2), 131-6.

Fluid inclusion in quartz grains in charnockite from Toppur area contain moderate to abundant CO₂ inclusions. The CO₂ inclusions occur azonal and scattered mostly towards the central portion of the quartz grain. From their distribution pattern they are classified as primary inclusions. The carbonic inclusions represent traces of synmetamorphic fluids, which were entrapped during granulite facies metamorphism at temperatures of 700°C to 750°C and pressures of 5.4 to 5.6 Kb.

^ssc4 illus, 11 ref

004619   Reddy H R V;Katti R J;Raveesha K P; Chandrashekara;Vikas S J;Babu R S N;Kumar K S S (Fisheries Dep, Environment and Ecology, College of Fisheries, Mangalore-575 002, Email: hrvreddy@yahoo.co.in) : Coastal water quality of Dakshina Kannada before and after Tsunami. Curr Sci 2005, 88(7), 1026-7.

004618   Ramasamy V;Murugesan S;Mullainathan S (Phys Dep, Annamalai Univ, Annamalainagar-608 002, Email: srsaranram@rediffmail.com) : Distribution and characterization of minerals in Cauvery river sediments by grain size analysis - a new approach by FTIR study. Indian Mineralogist 2005, 39(2), 91-107.

Mineralogical composition of Cauvery river sediments starting from Poombhuhar to Hoggenakal, has been determined by FTIR Analysiss. Cauvery river sediments are grouped into four categories using grain size separation technique. Category I (Rapid determination) shows eleven minerals-quartz, orthoclase feldspar, microcline feldspar, albite, kaolinite, illite, montmorillonite, chlorite, gibbsite, calcite and organic carbon. In addition to that 12 minerals were additionally identified through a thorough analysis. The absence of quartz in 74, 53 and 44 μm in category II indicates the elimination or loss of crystallinity of quartz. The presence of feldspar in 149 to 74 μm samples of category II is decreased which shows its disorderedness or loss of quantity. The influence of clay minerals and the absence of feldspars in 53 and and 44 μm indicates the transformation of feldspars to caly minerals by the way of leaching of feldspars due to flow of water in the Cauvery river. The transformation of goethite (320-177 μm) to haematite (149-44 μm) in category III shows its metamorphism. The crystallinity index of quartz and extinction coefficient of quartz, feldspar and kaolinite are computed. The variation in crystallinity index values dictates the transformation and leaching of quartz. The information about the well ordered quartz and its distribution is identified clearly only after separation of magnetic minerals.

13 illus, 2 tables, 15 ref

004617   Paul K J;Jaya Raj A A;Mahalakshmi K B (Geol Dep, Acharya Nagarjuna Univ, Nagharjuna Nagar-522 510) : X-ray diffraction, differential thermal and geochemical studies of low-level laterites of Visakhapatnam, Andhra Pradesh. Indian Mineralogist 2005, 39(2), 58-70.

Laterites in and around Visakhapatnam occur as small, isolated patches in low-levels ranging in elevation from 12 to 55 m above mean sea level. The laterites are conglomeratic in appearance with recemented gravel, pebbles and cobbles, derived mainly from sillimanite-feldspar gneisses (khondalites) and quartzites, which occupy most of the higher elevations of the area. The gravel, pebbles and cobbles are cemented with ferruginous matrix. The minerals associated with the laterites have been identified by optical, XRD and DTA techniques. Chemical analyses of selected laterites of this area have been carried out. Of all the laterite occurrences in this area, the laterites at Seethammadhara has shown a maximum of 46% of Fe₂O₃. From the above studies, the most important secondary minerals that are identified in low-level laterites of Visakhapatnam are goethite, haematite, kaolinite and halloysite along with minor quantities of relict primary minerals represented by quartz, sillimanite, garnet and orthoclase.

6 illus, 1 table, 20 ref

004616   Parthasarathy H (NO, Natn Geophysical Reseach Inst, Uppal Road, Hyderabad-500 007, Email: gpngri@rediffmail.com ) : Phase transition of amphiboles from the archaean section of the Kola superdeep well (12,148 meters) Russia and surface analogues. Indian Mineralogist 2005, 39(2), 71-83.

Temperature dependence of electrical resistivity and heat capacity of natural tremolite up to 1300 K is reposed for the first time. The samples used in the study, are natural tremolites from the core samples of Kola Superdeep well (KSDB-3, Zapolyarny, Russia) from a depth of 12148 m and a surface sample from Holenarsipur, Karnataka, India. Both the samples have witnessed identical peak metamorphic conditions. The electrical resistivity of the tremolite from KSDB-3 is 1.02 x 10¹¹ Ω cm at 415 and decrease exponentially with the increase of temperature up to 903 K, where the electrical resistivity increases from 1.412x10⁶ ° cm to 3.158 x 10⁷ Ω cm. The transition is interpreted as thermally induced decomposition of tremolite, as the transition in the temperature range of 903 K to 963 K is found to be irreversible in their electrical resistivity behaviour. This phase transition is also observed at 1050 K in DTA. Temperature dependence of heat capacity of tremolite up to 1300 also confirmed the phase transition. The phase transition observed in the KSDB-3 sample has been compared with the thermal behaviour of the surface sample of tremolite from Holenarasipur.

4 illus, 1 table, 25 ref

004615   Neelamani S (NO, Environment & Urban Development Division, Kuwait Institute for Scienti, P O Box 24885, 13109 Safat, Kuwait, Email: nsubram@kisr.edu.ku) : Subareal wave pressures, layer thicknesses, run-up and run-down velocity on sea walls. Indian J Mar Sci 2005, 34(3), 299-309.

Wave pressures, layer thickness, run-up and run-down velocities were measured on the splash/subareal zone (the part of the seawall which is partially in water during run up and partially in the air during run down) of plane seawalls for a wide range of hydrodynamic parameters and seawall slopes. The complete wave breaking range (spilling, plunging, collapsing and surging) is covered in the study. The maximum wave pressure in the subareal region can be as high as 1.2 times the static pressure due to water column equal to the incident wave height. The maximum wave pressure at any point is higher than the water pressure induced by the layer thickness due to the dynamic contribution of the flowing water on the seawall. The maximum run up and run down velocity can be as high as 25 times the maximum horizontal water particle velocity in deep water. The run-down velocity is found to be higher than the run-up velocity for the same input condition. Using the measured data, empirical formulae are proposed to predict the subareal wave pressures, layer thicknesses, and run-up and run-down velocities. The proposed formulae incorporate the surf similarity parameter and relative elevation of the location on the subareal region of the seawall. The empirical equations are simple, reliable and hence can be used for the optimal design of plane seawalls.

14 illus, 1 table, 18 ref

004614   Murthy K S R (NO, National Institute of Oceanography, Regional Centre, 176 Lawsons Bay, Visakhapatnam-530 017, Email: ksr@darya.nio.org) : First oceanographic expedition to survey the impact of the Sumatra earthquake and the tsunami of 26 December 2004. Curr Sci 2005, 88(7), 1038-9.

1 illus

004613   Mohan B S (Centre of Biosciences, T John Group of Institutions, B G Road, Bangalore-560 083, Email: mohanbettageri@yahoo.com) : (NULL). Curr Sci 2005, 88(7), 1021-2.

004612   Malleswara Rao M M;Ramana Murty T V;Rama Rao P;Lakshminarayana S;Subrahmanyam A S;Murthy K S R (National Institute of Oceanography, , Regional Centre, Visakhapatnam-530 017, Email: mmmrao@darya.nio.org) : Utility of natural generalised inverse technique in the interpretation of dyke structures. Indian J Mar Sci 2005, 34(3), 285-98.

Forward and Inverse methods of magnetic interpretation have been used to estimate the parameters of dyke like intrusion over the eastern continental shelf of India. In the forward problem, the tentative parameters of the causative source are assumed and anomalies are calculated using the anomaly equation, while inverse problem refers to methods of tracing the boundaries or outlines of anomalous bodies using an iterative approach. While solving the inverse problem, data, kernel has been generated through the model (i.e. partial derivatives of magnetic anomaly function with respect to model parameters at each station forming the kernel). In solving the coupled eigenvalue problem of covariance matrices of data kernel, Singular Value Decomposition (SVD) has been performed to build generalised Inverse Operator (GIO). This GIO is operated on the observed anomaly (with reference to the calculated) to yield improved model parameters. Data and model resolution matrices are computed to check the correctness of the solution and further analysis. The marine magnetic total field anomaly of continental shelf of Visakhapatnam is interpreted using GI technique, which revealed the causative source of the anomaly as a dyke model at a depth of 120 m below seabed.

8 illus, 5 ref, 19 ref

004611   Malathi M N;Srikantappa C (Geol Dep, Univ of Mysore, Manasagangotri, Mysore-570 006) : Highly saline fluids from Spodumene-Tantalite bearing pegmatites from Karighatta, Dharwar craton, Karnataka. Indian Mineralogist 2005, 39(2), 84-90.

Highly saline (upto 35 equiv. wt % NaCl) bearing primary fluid inclusions have been recorded in the spodumene-tantalite bearing pegmatite from Karighatt. The deposition of rare metals in pegmatite took place at temperaturtes of 150 to 300°C at pressue of 2 to 3 kbar. Similar high salinity (upto 22 equiv. wt % NaCl) inclusions have also been recorded in the associated granitic rocks in the area, suggesting a close genetic link. The origin of rare metal pegmatite and granites due to partial melting of upper crustal material took place probably during Mesoproterozoic time.

2 illus, 1 table, 12 ref

004610   Das N;De U K (Environmental Science Research Programme, Faculty of Science, Jadavpur University, Kolkata-700 032, Email: deutpal@hotmail.com) : Turbulent eddy characteristics in temperature and wild field of surface layer during MONTBLEX'90 over Jodhpur, India. Indian J Radio Space Phys 2004, 33(6), 380-90.

Study of turbulent eddies is a very challenging topic, as it plays a dominant role in controlling the transport of atmospheric constituents in the tropical boundary layer. Tower data of temperature and horizontal wind speed collected by fast response sensors during MONTBLEX'90 (MONsoon trough Boundary Layer Experiment, 1990) field experiment, are considered here, to study the characteristics of the eddies. For this purpose autocorrelation has been performed, by applying a series of lags to different data set. Studying the value of autocorrelation, an attempt is made to determine the type and nature of turbulence eddies, which dominates in the surface boundary layer during the period concerned. The observation shows that turbulent plumes have a specific temporal scale during the period of study. At the same time the approximate spatial extension of the plumes in both horizontal and vertical directions is suggested for some general days as well as for some synoptically significant days. Lastly, comparative studies about the sensitivity of the sensors have been performed.

10 illus, 3 tables, 13 ref

004609   Bansal A R;Dimri V P (National Geophysical Research Institute, , Uppal Road, Hyderabad-500 007, Email: vpdimri@ngri.res.in) : Interpretation of gravity data over the 85°E ridge and afanasy nikitin seamount using spectral method. Indian J Mar Sci 2005, 34(3), 279-84.

The 85°E ridge is an enigmatic buried aseismic ridge having the peculiar negative gravity anomaly in the north and positive anomaly in the south. Different theories are proposed for the negative anomaly over the 85° ridge. High- resolution two-dimensional satellite gravity data over 85° ridge is interpreted using the spectral analysis method covering the area from 5°S to 18°N. The area consists of the Afanasy Nikitin seamount, partially buried hills and the 85° ridge. Twelve overlapping blocks of 3° x 3° are selected to calculate the depth of anomalous sources. The two layers of anomalous sources are observed for all blocks. The different depth values of causative sources are found for different portion of the 85°E ridge. The deeper depth values for each block are representing the crustal thickness. The maximum thickness of 25.6 km was found for block 10 covering the area between latitude 12°N to 15°N. The average crustal thickness decreases from north to south along 85° E ridge. The reason of negative free air gravity anomaly below the 85°E may be due to the depression in the Moho.

4 illus, 1 table, 19 ref

004608   Banerjee M;Mitra S;Dutta S (Botany Dep, University of Calcutta, 35, Ballygunge Circular Road, Kokata-700 019, Email: manjubanerjee@rediffmail.com) : First record of late palaeozoic euramerian calamitalean foliage shoot Annularia sternberg in the late early permian (Barakar formation) glossopteris floral assemblage of peninsular Indian lower gondwana. Curr Sci 2005, 88(7), 1040-2.

3 illus, 22 ref

004607   Banakar V K (Geological Oceanography Division, National Institute of Oceanography, Dona Paula-403 004, Email: banaka@darya.nio.org) : δ<. Indian J Mar Sci 2005, 34(3), 249-58.

Carbon-isotopes (δ¹³C) composition of benthic foraminifera has been extensively used to understand the link between deep-water circulation and climate. Equatorial Indian Ocean δ¹³C records of planktic- and benthic-foraminifera together show an unexplained shift in the long-term mean oceanic-δ¹³C around the penultimate glacial termination (T2: 132 ka). The time-series planktic- and benthic- species δ¹³C records exhibit two distinct mean-δ¹³C levels. The low mean-δ¹³C characterises the pre-T2 period (250 ka - 132 ka), while the post-T2 (<126>95 ka - Present) period records high mean-δ¹³C, generating a one-time shift of <126>0.4% within the last <126>250 kyr time-period. This shift is a result of consistently higher-δ¹³C in post-T2 glacial (and interglacial) periods as compared to the pre-T2 glacial (and interglacial) periods, and begins around the T2 (<126>132 ka), lasts until <126>95 ka, and sustained through the T1. The normally observed glacial-interglacial δ¹³C variations of <126>0.3% occur as secondary fluctuations around the long-term primary mean-levels in the Indian Ocean, as well as in other oceans. The T2-δ¹³C shift appears to be an inherent feature of the world oceans although with certain timing offsets. Therefore, it should represent a fundamental change in deep-ocean circulation (nutrient) dynamics. But, the leading hypotheses of circulation-driven oceanic distribution of δ¹³C fail to explain the observed mean-δ¹³C shift. Therefore it is proposed that, in addition to changes in deep-water circulation, the oceans before T2 were characterised by significantly lower-δ¹³C than after. Such low-δ¹³C mean-ocean during the pre-T2 period might have been the result of significantly increased transfer of terrestrial light-carbon to the ocean reservoir due to changes in global wind patterns.

4 illus, 1 table, 56 ref

003492   Vasanthi A;Mallick K (NO, National Geophysical Research Institute, Hyderabad-500 007, Email: mallik_ku@yahoo.com) : Bouguer gravity modelling of central Cuddapah basin. J Geol Soc India 2005, 66(2), 171-84.

Bouguer gravity data over a large central part of the Cuddapah basin have been obtained by digitising the 5 - mGal contour map. The regional and residual components have been separated by a newly developed finite element scheme, contoured with colour scale and residual anomalies are modelled for the basement structure in several profiles. The data is thereby rendered more attractive and easily visualised. The thickness of the sediments derived by gravity modelling has been compared with that along two deep seismic sounding (DSS) profiles. The thick columns (<126> 9 km) of sedimentary formations in the Proterozoic Cuddapah basin are likely to interest the organizations dealing with hydrocarbon exploration. An interesting relationship has been brought out among the three mantle-derived rocks, i.e. the volcanics of the western margin, the kimberlite emplacement and the dyke swarms. These three features seem to share a common gravity field. Based on the correspondence between the locations of kimberlite pipes and lamproites and the regional gravity anomalies authors has suggested the kimberlites and the lamproites to occur along two concentric rings with the centre lying approximately in the southwest region of the Cuddapah basin. Further, the occurrences of kimberlite pipes and lamproites at Vijayawada and Ramannapet on northeast, Narayanpet on the west and Kalyandurg on the southwest led to suggest a third ring. In fact, three new kimberlite pipes have been reported at Siddanpalli between Gadwal and Raichur that lie on the third ring. The gravity studies also indicate the Cuddapah Front on the east to form a possible collision boundary.

10 illus, 1 table, 50 ref

003491   Tiwari R N;Verma P L;Nigam S K (Research Scholar, A.P.S. University, Rewa, Madhy Pradesh) : Interplanetary shocks, the causes of intense geomagnetic storms. Acta Cienc Indica-Phys 2005, 31(1), 91-4.

The study of geomagnetic storm <131>-100 nT with interplanetary shocks, shows that intense geomagnetic storms strongly associated with interplanetary shock. It was found that almost all the geomagnetic storm <131>-325 nT are associated with shocks or SSC.

003490   Tharadevi C S;Vasantha Kumar B;Natarajan P; Satarkar V;Arabaska F;Narina V (Zoology Dep, Sree Ayyappa College for Women, Chunkankadai) : Physico-chemical characteristics of a man made rock pool in Kanyakumari district, Tamil Nadu. Proc Zool Soc India 2005, 4(1), 9-15.

The ecological status of man made rock pool in terms of various physicochemical parameters was assessed for a period of one year from June 2002 to May 2003. Parameters like water temperature, transparency, pH, total suspended solids, electrical conductivity, free carbondioxide, total alkalinity, dissolved oxygen, NO₃N, inorganic PO₄-P, chloride, calcium, magnesium and sulphate showed much variation during different months.

3 illus, 28 ref

003489   Sundar Raju P V (National Geophysical Research Institute, , Hyderabad-500 007, Email: pvsraju@ngri.res.in ) : Report on ocelli bearing mafic-ultramafic rock from South of Arsikere in Hassan district. J Geol Soc India 2005, 66(2), 145-6.

A preliminary report on the ocelli-bearing mafic-ultramafic rock from Honnavalli village near Arsikere in Hassan district of Karnataka is presented.

^ssc2 illus, 1 table, 6 ref

003488   Sinha R (Engineering Geosciences Group, Department of Civil Engineering, Indian Institute of Technology Kanpur, Kanpur-208 016, Email: rsinha@iitk.ac.in) : Why do gangetic rivers aggrade or degrade?. Curr Sci 2005, 89(5), 836-40.

The rivers draining the Gangetic plains exhibit remarkable geomorphic diversity, and this has consequently characterized the rivers to be dominantly aggradational in the Eastern Gangetic Plains (EGP) and degradational in the Western Gangetic Plains. Author has suggested that steam power and sediment supply are the two main fluvial parameters which govern the aggradation or degradation in river systems which, in turn, are controlled by inherent catchment parameters such as rainfall and tectonics. The aggradation/degradation behaviour strongly influences major fluvial processes such as channel avulsions and flooding and therefore has wide ranging implications for river management projects in the country.

4 illus, 28 ref

003487   Singh B P;Pawar J S;Mithila (Postgraduate Department of Geology, University of Jammu, Jammu-180 006, Email: bpsingh_in@yahoo.com) : Is Jammu bauxite a reworked basalt derived bauxite?. J Geol Soc India 2005, 66(2), 157-60.

The sedimentary structure in the bauxite deposits of the Jammu area are suggestive of a reworked bauxite precursor. Trace elements and REE concentrations show that the precursor bauxite originated from the weathering of basalt. It means that the bauxite forms a part of the earliest interval of the Himalayan foreland sedimentary sequences.

^ssc6 illus, 1 table, 22 ref

003486   Sarma A A L N;Srinivas S;Karthikeya A (Department of Meteorology & Oceanography, Andhra University, Visakhapatnam-530 003) : Studies on aberrations in climate impacts - water balance model. J Indian Geophys Union 2005, 9(3), 209-18.

Global climate has been already perturbed due to variations in orbital forcing and man made factors and the footprints of it are traceable in the world climate spectrum (IPCC 1995). It is also evidenced world-wide that man made factors are aggravating the global effects of climate change in terms of triggering extreme weather events. The paper address critically not only the spatiptemporal variations of moisture and thermal regimes of India through water balance model but also the occurrence of varied degrees of humidness and droughts in moist and dry climates respectively for selected stations that are drawn from its climate spectrum by selecting not less than two stations representing north and south of each of its climate zones. The paper then proceeds in analyzing proneness to varied degrees of droughts on All India basis. Climate stability and the basic water budget elements in extreme climate shifts for the selected stations are also studied. The investigation presents the modulation of basic water budget elements of All India during extreme climate shifts of wetness and dryness in the context of LNSO and ENSO signals and their climate implications are discussed. Finally, trends in All India moisture regime in the context of LNSO and ENSO signals are also reported.

4 illus, 4 tables, 12 ref

003485   Saraf A K;Choudhury S (Department of Earth Sciences, Indian Institute of Technology Roorkee, Roorkee-247 667) : Thermal remote sensing technique in the study of pre earthquake thermal anomalies. J Indian Geophys Union 2005, 9(3), 197-207.

Pressure built-up due to tectonic activities and also associated subsurface degassing might create changes in thermal regime prior to an earthquake event and if by any technique this change is detected, it can provide very important clues about future earthquake activities. Thermal satellite remote sensing which can sense the earth's surface emissivity at regular interval introduces a new way of analyzing this phenomenon. Using NOAA-AVHRR thermal datasets, few major past earthquakes (Bhuj (India), Boumerdes (Algeria), Bam (Iran) etc.) were analyzed for studying the thermal changes before and after the earthquakes. The study was successful in detecting pre-earthquake thermal anomalies prior to all these earthquakes. Significant thermal anomalies with a rise in temperature of about 5-10<144>C in the vicinity of the epicenters have been observed. The anomalies disappeared along with the earthquake events. Further, using passive microwave SSM/I sensor datasets from DMSP satellites the occurrence of the phenomenon of pre-earthquake thermal anomalies for few more earthquakes around the world were observed.

6 illus, 11 ref

003484   Saikia K;Sarkar B C (NO, Central Mining Research Institute, Dhanbad-826 001) : Geostatistical studies of a gold prospect in sidhi district, Madhya Pradesh. J Geol Soc India 2005, 66(2), 229-41.

Gurahar Pahar gold prospect, located in Sidhi district of Madhya Pradesh, is one of the most promising gold prospects of Mahakoshal greenstone belt in Central India. Gold mineralization is generally associated with sheared quartz veins, proximally found tuffaceous phyllite, carbonate veins and primary sulphides. The paper attempts an integrated modelling for resource evaluation of Gurahar Pahar gold prospect. The integrated approach combines together: (i) a geological understanding of the nature of gold mineralization from field observable evidences on host lithology, mode of occurrence, structural elements, viz. schistosity and foliation, and drill hole intersections from published exploration data; (ii) classical statistical modelling; and (iii) geostatistical evaluation for development of mineral inventory of the central part of Gurahar Pahar gold prospect. The integrated geostatistical resource evaluation using block kriging technique and grade-tonnage relations of the central part of the prospect, bounded between 1040 S to 1540 S and 140 E to 840 E of the local grids and between 291 mRL and 181 mRL, indicate 3,36,000 tonnes of gold ore at a cutoff of 0.5 g/t with an average Au of 0.74 g/t.

12 illus, 5 tables, 27 ref

003483   Rao M J;Ramana J V;Venugopal R;Rao M C (Department of Geology, Andhra University, Visakhapatnam-530 003) : Geochemistry and ore mineralogy of ilmenite from beach placers of the Visakhapatnam-Bhimunipatnam deposit, Andhra Pradesh. J Geol Soc India 2005, 66(2), 147-50.

Ilmenite from the beach and dune environments of the Visakhapatnam-Bhimunipatnam placer sand deposit has less TiO₂ and more total iron contents, as compared to its stoichiometric composition. Its trace elemental concentrations indicate its basic parentage. It has exsolution features and four types of intergrowths, viz. ilmenite-hematite, hematite-ilmenite, graphic intergrowth and ilmenite-rutile. Hematite phase in ilmenite incorporate excess iron in the structure of ilmenite. Based on the geochemical and ore mineralogical aspects, ilmenite of study area is more suitable for pigment-manufacturing than to synthetic rutile preparation.

^ssc2 illus, 1 table, 9 ref

003482   Radhakrishna Murthy I V;Rama Rao P;Sudhakar K S;Bangaru Babu S (Department of Geophysics, Andhra University, Visakhapatnam-530 003) : Moho structure beneath the eastern ghat mobile belt and adjacent Bastar craton as deduced from gravity anomalies. J Indian Geophys Union 2005, 9(3), 167-71.

A typical gravity profile across Eastern Ghat Mobile Belt (EGMB) and adjacent Bastar Craton was selected from the available Bouguer Gravity Map (NGRI 1975) of India. The Bouguer anomaly map is deceptive as it revealed a low over a background rise of gravity anomaly from the west to the coast. A careful regional-residual separation brought but two prominent highs in place of the frequently quoted low. These highs could be explained by structures at the Moho.

4 illus, 8 ref

003481   Qasim S Z (Society for Indian Ocean Studies, , Secular House, 1, Aruna Asaf Ali Marg, New Delhi-110 067) : Tsunami and its after effects. Bionotes 2005, 7(3), 79-81.

2 illus, 2 ref

003480   Naidu T Y;Kamalakaram S;Kaladhar R (Department of Geology, Andhra University, Visakhapatnam-530 003, Email: yntalari@yahoo.com) : Recent benthic foraminiferal biofacies and its environmental significance in the Goguleru creek, coastal Andhra Pradesh. J Geol Soc India 2005, 66(2), 223-8.

The Goguleru creek is a supralittoral brackish water creek located between Krishna and Godavari Delta in coastal Andhra Pradesh. The creek is divisible into the two domains of drain and lagoon. R- mode cluster analysis was carried out on benthic foraminiferal total population for the months of December 1988 (Winter) and May 1989 (Summer) and four and three major biofacies were recognized respectively. Two of the biofacies are dominated by agglutinated forms while the others are dominated by Ammonia and Asterorotalia. The distribution of these biofacies corresponds to characteristic sub-environments present in the creek, such as marshy, brackish and open- sea near shore/beach. Such studies may help to recognize similar paleoenvironments.

3 illus, 1 table, 15 ref

003479   Muthu R P;Muraleedharan C (Geological Survey of India, , Chennai-600 090, Email: muthurp@rediffmail.com) : Causes and mechanism of Amboori landslide of 9th November, 2001, Thiruvananthapuram district, Kerala. J Geol Soc India 2005, 66(2), 203-8.

Amboori landslide, one of the worst natural disasters of Kerala, had taken a toll of 38, besides exposing the vulnerability of the hilly state to such mishaps. The failed slope located in Kurisumalai hill, was fairly steep at 32<144> and was covered by overburden consisting of colluvial deposits, boulders and weathered rock. Its contact with the underlying migmatised garnet-biotite gneiss and garnetiferous quartzofeldspathic gneiss was marked by a thin layer of lithomargic clay which represented a weak plane. While cultivation on the slope blocked the drainage course, road cutting undermined the toe support. Rainfall during the monsoon was above average. It culminated in a heavy downpour of 82.4 mm in a short span of less than 2 hours on a delicate slope and triggered a planar failure between the bed rock and overburden. Corroborative evidences are lacking to the media claims that linked the slide to earthquake, lightning, thunder etc. Several settlements in the area are facing imminent danger from unstable slopes and precariously perched boulders. Identification of such spots by carrying out detailed survey and taking preventive measures are considered a priority requisite. Future development based on Landslide Hazard Zoning and enforcing of housing codes are recommended for the Amboori area.

6 illus, 6 ref

003478   Mujumdar V R;Bhide U V;Nagar S G;Ghanekar S P;Seetaramayya P (Indian Institute of Tropical Meteorology, , Dr Homi Bhabha Road, Pashan, Pune-411 008) : Thermodynamic characteristics over north Bay of Bengal during active and weak monsoon phases of BOBMEX-1999. J Indian Geophys Union 2005, 9(3), 219-33.

The Bay of Bengal Monsoon Experiment (BOBMEX-99) was carried out during peak monsoon months of July and August, 1999. The surface and the upper air Radiosonde data acquired onboard Ocean Research Vessel (ORV) Sagarkanya, at the stationary position 17.5<144>N, 89.0<144>E, during this experiment have been analysed for the periods 28 July to 5 August (Phase I) and 14 to 22 August (Phase II). The analysis of the various parameters over Indian region has shown intra-seasonal fluctuations of active and weak monsoon episodes during these two phases respectively. In addition, day to day variations in the vertical profiles of RH, <113>e, <113>es and P in the midtroposphere, at the stationary, position of the ship, are observed to be more significant during Phase I than Phase II. The atmosphere near the surface over north Bay of Bengal seems to be conducive to the formation of convection during both the phases. However, over the north bay, three intense synoptic scale disturbances are formed during Phase I while, only a single upper air cyclonic circulation is developed during Phase II.

10 illus, 1 table, 12 ref

003477   Metternicht G;Gonzalez S (Department of Spatial Sciences, Curtin University of Technology, GPO Box U1987, Perth 6845, Western Australia, Email: g.metternicht@curtin.edu.au) : Modelling land cover changes: Fuzzy thresholding for the separation of change from no-change areas. Int J Ecol envir Sci 2004, 30(4), 351-62.

The study presents the framework for the implementation of a non-heuristic technique for thresholding of change images derived from multi-temporal analysis of remotely sensed data using pre-classification techniques. The approach is based on fuzzy sets and fuzzy logic, and it assumes that accurate separation of change/no-change can be achieved if the membership function of the fuzzy model is adapted to the shape of the histogram of the change image. The output from the model is a 'possibility of changes' image, as opposed to the traditional binary change/no-change image. The accuracy in the separation of change/no-change areas is assessed using the error matrix and its associated user's, producer's and overall accuracy measures. The overall and per class kappa coefficient are used as additional measures of accuracy. The final step involves comparing the performance of the 'fuzzy thresholding' against the 'symmetric thresholding', and determining a fuzzy linguistic value (and its associated fuzzy interval) that better reflect the separation between areas of change/no-change.

6 illus, 6 tables, 30 ref

003476   Mainkar D (Dirctorate of Geology and Mining, , Raipur-492 006, Email: datta_mainkar2002@yahoo.co.uk) : New find of coal bearing barakar formation in Jagima-Patna area, Surguja district, Chhattisgarh. J Geol Soc India 2005, 66(2), 154-6.

First report on the find of rocks of Barakar Formation, which is in Jagima-Patna area in north-eastern Chhattisgarn, covered in Survey of India toposheet 64 M/ll in Kusmi tehsil of Surguja district. These coal bearing formations have been located (Mainkar and Minj, 2004) during reconnoitory survey for bauxite by the Directorate of Geology and Mining, Chhattisgarh.

^ssc3 illus, 1 table, 6 ref

003475   Krishnaswamy V S;Nandan K R R (NO, , 409, S. Lexington Ave, White Plains, NY-10606, USA) : The satpura uplift and the palaeoclimate of the holocene and auxiliary evidence from the Valmiki Ramayana. J Geol Soc India 2005, 66(2), 161-70.

The available geological, floral and faunal evidences support the existence of a very cold climate in the Peninsular India during the Pleistocene. Against this background, the middle to late Holocene event of a snowy winter at Panchavati described in the Valmiki Ramayana has been analysed. The geological evaluation of the existing information indicates a 300 m epeirogenic uplift of the Satpura range and the adjacent areas, during the upper Pleistocene, followed by about 1000 m of orogenic uplift of the Satpura crustal block, bounded by the seismogenic, Moho-reaching, Narmada and Tapti graben-faults that were reactivated in the Holocene, as proved by recent geological mapping and geothermal drilling. The uplift may have taken place, either, by sudden displacements, or, by slow, tectonic creep, or, by a combination of both the processes, thereby raising the height of a pre-existing Satpura range. This probably blocked partly, the route of very cold, arctic type of air-flows descending from the Himalayan glaciers that had then reached lower elevations of 1000 to 1500 m and, interacting with the moist winds blowing eastwards from the Arabian Sea, thereby giving rise to the snowfall at Panchavati. The warming up phase of the Quaternary commenced at the end of the Pleistocene glaciation. This continued up to the commencement of the late Holocene, and also caused the gradual recession of the of the snouts of the Himalayan glaciers to higher elevations. This resulted in the cessation of the arctic type of winds coming down to the Peninsula from the Himalayas, thus terminating the snowy winters prevalent earlier. The astronomical method of dating the Ramayana gives the most probable age of the epic as 2000 B.C. and the less probable age of 4000 B.C., by traditional (historical and genealogical) methods of dating. The range of the above two ages tallies with the geologically deduced range of age of middle to late Holocene for the palaeoclimatic events described in the Panchavati area. It is suggested that the palaeoclimatic and other environmental changes of the Quaternary period in the Sonata area of the Peninsula be subjected to detailed studies in the future.

2 illus, 43 ref

003474   Joseph A;Prabhudesai R G (NO, National Institute of Oceanography, Dona Paula, Goa-403 004, Email: joseph@darya.nio.org) : Need of a disaster alert system for Indian through a network of real-time monitoring of sea-level and other meteorological events. Curr Sci 2005, 89(5), 864-9.

Need of a disaster alert system (DAS) capable of online transmission of real-time integrated sea-level and surface meteorological data is discussed. In addition to INSAT platform transmit terminal, VHF, etc., the ubiquitous cellular phone network would be an important option that can be effectively utilized to provide the crucial communication capability to DAS. Such a system would also provide a sufficiently large near-real-time database for running storm-surge models and prediction of any suspected destructive surge events at vulnerable coastal belts as well as complement any deep ocean tsunami warning system that India might put in place. Web-enabled DAS network with authorized access would facilitate viewing real-time/near-real-time coastal sea-level and surface meteorological events, ensuring data security and confidentiality.

5 illus, 1 table, 15 ref

003473   Jagadeesan P;Mishra K S;Ramesh Babu P V (Atomic Minerals Directorate for Exploration and Research, Department, , Civil Lines, Nagpur-440 001) : New occurrence of manganocolumbite from late proterozoic pegmatites of Bhurpidungri, Jharsuguda district, Orissa. J Geol Soc India 2005, 66(2), 141-4.

Manganocolumbite in the pegmatites of Bhurpidungri (Lat: 21<144>51'30": Long: 84<144>15'52", T.S.No.73C/5) in the Jharsuguda district of Orissa is reported for the first time from the pegmatites of India. It contains upto 18.46<37> MnO, with an average (n=8) of 14.52<37> MnO, 7.26<37> FeO^(T), 60.18<37> Nb₂O₅ and 14.33<37> Ta₂O₅. A swarm of pegmatites is exposed, intruding at the contact of granite gneiss and amphibolite/charnockite near the Bhurpidungri village. These pegmatites are well-zoned with prominent quartz core, intermediate zone and wall zone. About four tonnes of manganocolumbite has been estimated in the gravels of these pegmatites for exploitation. Apart from this, beryl is also found in sufficient quantity.

^ssc3 illus, 3 tables, 9 ref

003472   Dubey D P;Tiwari R N;Dwivedi U (NO, , 7/275 Murlidhar Colony, Civil Lines, Rewa-486 001) : Ferruginous nodules from the Govindgarh sandstone of the Rewa group of the Vidhyan supergroup, Chhuhia, sidhi district, Madhya Pradesh. J Geol Soc India 2005, 66(2), 151-3.

Occurrence of sand filled ferruginised nodules from the shaly unit in the basal part of Gonvindgarh Sandstone of the Rewa Group of the Vindhyan Supergroup, is discussed. Randomly oriented within the host sediment, the nodules range in length from 2 cm to 25 cm. Width and thickness are variable within the nodule. Nodules show no relationship with the bedding of the host rock. Nodules are made up of quartz grains, micas and haematite. Poikilitic growth, due to precipitation of ferruginous material within cavities of the host sediment, is suggested as the possible mode of origin of the nodules.

^ssc3 illus, 6 ref

003471   De U S;Dube R K;Rao G S P (Visiting Faculty Department of Environmental Science, University of Pune, Pune, Maharashtra) : Extreme weather events over India in the last 100 years. J Indian Geophys Union 2005, 9(3), 173-87.

India being mainly an agricultural country the economy and further its growth purely depends on the vagaries of the weather and in particular the extreme weather events. The information on extreme weather events lie scattered in the scientific and technical papers and in the research work of many authors and if put together will help the research community for further analysis. The authors in the paper has discussed a factual and a brief review of the extreme weather events that occurred, in India during the last 100 years (1901-2004). The socio-economic impacts of the extreme weather events such as floods, droughts, cyclones, hail storm, thunderstorm, heat and cold waves have been increasing due to large growth of population and its migration towards urban areas which has led to greater vulnerability. In recent years as per WMO review global losses from such extreme weather events is about US $ 50-100 billion annually with loss of life of about 2,50,000. Thus, greater efforts are needed to improve the forecast skill and use these better forecasts in disaster management.

1 illus, 7 tables, 42 ref

003470   Bisht B S;Ali M A;Pande A K;Pavanagaru R (Atomic Mineral Directorate for Exploration and Research, Department o, , Hyderabad-500 016, Email: drbisht@rediffmail.com) : Geological characteristics of the iron-uranium mineralisation in the lesser Himalayan region of Arunachal Pradesh. J Geol Soc India 2005, 66(2), 185-202.

In the Lesser Himalayan region of Arunachal Pradesh, northeastern India, iron-uranium (Fe-U) mineralisation characterises the volcano-sedimentary sequence belonging to the Middle-Late Proterozoic Siang Group. The host rocks metamorphosed in the greenschist to lower amphibolite facies are intensely deformed. The lithological, structural, petrological and geochemical parameters indicate involvement of three distinct processes resulting in the Fe-U mineralisation. These comprise early sedimentary deposition, mainly of Fe-oxides, Fe-sulphides and minor U, followed by local metamorphic redistribution of U, and lastly hydrothermal mineralisation leading to deposition of mainly uranium and REE bearing minerals and minor Fe-Cu sulphides. Syngenetic iron oxide mineralisation occurs in the form of ironstone containing 44 to 63 wt percent Fe. The lithological association of ironstone and low contents of Ti, V, Cr, Co and Ni in magnetite support this contention. Sulphides, mainly pyrite with subordinate chalcopyrite and molybdenite form bands, stringers and veins. The sulphur isotopic ratios (<100>³⁴S) of pyrites in different formations exhibit a small range of+11.1 to +15.8<37>o suggesting derivation of sulphur mainly from the seawater sulphate and hydrothermal sources. Variation in the U-content of the rocks in the mineralisation zone is attributed to the differences in the composition of precursor sediments and also to differential mobility of uranium during progressive metamorphism. Epigenetic U-mineralisation related to quartzo-feldspathic veins occurs along fractures and foliations and has caused wall rock alterations such as chloritisation, epidotisation, silicification, and serialisation. Association of uraninite, brannerite, davidite, fluorite, tourmaline, albite, biotite and quartz characterise the uraniferous rocks. These rocks also contain significant REEs. The calc-alkaline granitic magma of Cambro-Ordovician Period is considered to be the ultimate source of U. Oxidation of host rocks resulted in extensive goethitisation and kaolinisation in the weathering zone.

8 illus, 5 tables, 57 ref

002425   Vinay Kumar;Krishnan R (Indian Inst of Trop Meteorology, , Pune-411 008) : On the association between the Indian summer monsoon and the tropical cyclone activity over northwest Pacific. Curr Sci 2005, 88(4), 602-12.

An analysis of observed typhoon tracks and daily global wind data for 56 years (1948-2003) reveals that large-scale circulation anomalies associated with the inter-annual variability of the Indian monsoon play an important role in influencing the tropical Pacific cyclone activity. The cyclogenesis over northwest and tropical west-central Pacific is found to be about 1.33 times higher during weak monsoon years compared to strong monsoon years. Also, there is greater tendency for the Pacific cyclones to move northward and recurve (to the north of 20°N) during weak monsoon years. The enhanced cyclogenesis during weak monsoon years is found to be associated with enrichment of low-level cyclonic vorticity anomalies over a wide region of the subtropical Pacific extending from the China Sea, Taiwan and the Philippines region to the central Pacific; while the movement of the tropical cyclones is associated with anomalies of upper-tropospheric steering currents. Given that the interannual variability of the large-scale circulation over the Indo-Pacific sector is crucially determined by the El Nino/Southern Oscillation (ENSO) conditions, the present findings raise several questions pertaining to interactions among the large-scale circulation anomalies, tropical convection and the Pacific cyclonic disturbances, which are likely to provide better understanding of the dynamical linkages between monsoon variability and ENSO.

7 illus, 1 table, 38 ref

002424   Tiwari R K;Sri Lakshmi S (Natn Geophys Res Inst, , Hyderabad-500 007, Email: rk_tiwari3@rediffmail.com) : Some common and contrasting features of earthquake dynamics in major tectonic zones of Himalayas using nonlinear forecasting approach. Curr Sci 2005, 88(4), 641-7.

Although the Northeast, Western and Central Himalayas distinctly differ in their tectonic activities, this distinction is not examined from a dynamical perspective. The identification of dynamical pattern is, however, central for characterizing the appropriate models of seismic hazard analysis in such critical tectonic regions. Authors has examined here the temporal evolution of seismicity (M ≥ 4) of the Central Himalaya (CH), Western Himalaya (WH) and Northeast Himalayas (NEH) for the period 1960-2003 using the modern nonlinear forecasting scheme to decipher the comparative determinism of underlying dynamical patterns, which may yield insight into earthquake processes. The nonlinear analyses of monthly resolution earthquake frequency time series suggest that earthquake processes in all three regions evolved on a high-dimensional chaotic plane, though with a contrasting predictive pattern. The predictive correlation analysis suggests that the available earthquake data of the NEH and WH can be predicted by more than 40-50%, whereas CH data only by 0-30%, implying that the earthquake dynamics in the NEH and WH are better 'organized' than in the CH. The significant distinction in the earthquake dynamical pattern seems to be associated with the underlying seismo-tectonics of these three regions. These results may place significant constraints for developing criteria to test the models of Himalayan earthquakes on a more regorous and quantitative basis.

6 illus, 36 ref

002423   Suryabhagavan K V;Seetharamaiah J (Dep of Geol, Andhra Univ, Visakhapatnam-530 003) : Textural reflections of the Iskapalli Lagoon, East coast of India. J Geol Soc India 2005, 65(6), 762-5.

In order to understand the sediment dynamics of the Iskapalli lagoon, located in northern part of the Penner delta, east coast of India, grain size parameters were analyzed for 36 sediment samples from tidal channel, lower and upper lagoons. Sediment distribution pattern indicates that tidal channel is mostly occupied by sand, lower lagoon by mixed clayey sand and sandy mud and upper lagoon mostly by clayey sand.

2 illus, 1 table, 6 ref

002422   Sukhchain;Srivastava P K (Dep of Geol, Univ of Jammu, Jammu-180 006, Email: psrivast@sancharnet.in) : Development of perthite in the topaz bearing degana granite, Rajasthan. J Geol Soc India 2005, 65(6), 758-61.

Perthites are important disequilibrium textures found in the topaz bearing Degana Granites. Out of the two types of the perthites in the Degana Granite, the fine-grained stringlet type perthite is found in the unaltered portion while the dominant coarser type replacement perthite is present in the potassic alteration zones. A schematic model for the progressive evolution of perthite texture in the potassic alteration zone of the Degana Granite is proposed.

^ssc3 illus, 9 ref

002421   Subrahmanyan C;Gireesh E;Gahalaut V (NO, , ) : Continental slope characteristics along the Tsunami-affected areas of eastern offshore of India and Sri Lanka. J Geol Soc India 2005, 65(6), 778-80.

3 illus, 4 ref

002420   Subrahmanyam A V;Sinha K K;Bagchi A K (Atom Miner Directorate for Explor and Res, , Begumpet, Hyderabad-500 016, Email: avsamd@rediffmail.com) : A note on petrography and chemistry of microgranular enclaves and granitoids around Talbahat, Lalitpur district, Uttar Pradesh. J Geol Soc India 2005, 65(1), 92-6.

In the Bundelkhand terrain of Uttar Pradesh (U.P.) grey and pink granites are the dominant rock types and their petrography and chemistry have been earlier studied by others. These granites intrude gneisses, migmatites, banded iron formation and metasediments. Based on cross cutting relationships and xenoliths in younger granites, Rahman and Zainuddin (1993) recognized five types of granites. Geochemistry of granites revealed subduction related magmatism. Presents field, petrographic and chemical characters as well as genetic aspects of the mafic, felsic enclaves and their host granites in the southwestern parts of the Bundelkhand massif around Talbahat, Lalitpur District, U.P.

3 illus, 1 table, 10 ref

002419   Subrahmanyam A V;Anil Kumar V;Desapati T; Deshmukh R D;Viswanathan G (Atom Miner Directorate for Explor and Res, , Begumpet, Hyderabad-500 016, Email: bsoisap@yahoo.co.in) : Discovery of micro-diamonds in beach placers of the east coast, Andhra Pradesh, India. Curr Sci 2005, 88(8), 1227-8.

2 illus, 4 ref

002418   Somani O P;Sarbajana C;Sinha R P (Dep of Atom Energy, Atom Miner Directorate for Explor and Res, West Block-7, R K Puram, New Delhi-110 066, Email: somaniop@rediffmail.com) : Tantalum in tin slag - a report from Bastar pegmatite belt, Chhattisgarh, India. J Geol Soc India 2005, 65(1), 101-4.

The Bastar pegmatite belt, Chattisgarh, India mainly consists of cassiterite-bearing pegmatites. The cassiterite concentrate recovered from pegmatite/colluvium is enriched in tantalum in the range of 3.1 to 14.9 % Ta₂-O₅. The tin slag remaining after smelting of cassiterite is enriched in tantalum with average 14.95% Ta₂O₅. The tin slag therefore is considered a potential source of tantalum with high grade.

3 tables, 17 ref

002417   Sinha H N;Srivastava S S;Peters J (Dep of Geol, Vinoba Bhave Univ, Hazaribagh-825 301, Email: hnsinha2003@yahoo.co.in) : Palaeoenvironmental deductions of microfossil flora and fauna of the Shiala and Yong formations, Tethyan Garhwal Himalaya. J Geol Soc India 2005, 65(1), 26-42.

5 illus, 2 tables, 81 ref

002416   Singh V;Vijay Kumar;Srivastava S L;Mittal S (Western Himalayan Regional Cent, Natn Inst of Hydrology, Opp Military Hospital, Satwari, Jammu Cantt-180 003) : Monitoring of soil moisture movement in unsaturated zone using TDR. J Indian Wat Resour Soc 2005, 25(1), 61-6.

Movement of soil moisture in unsaturated zone has been studied using TDK (Time Domain Reflectometry). For this purpose, an experiment has been carried out in the field to monitor the soil moisture below the ground surface at different depths and at different times simultaneously. Physical properties of soil, such as soil type, saturated hydraulic conductivity, bulk density, porosity and soil moisture characteristic have been calculated in the laboratory. Soil moisture obtained by TDR has been calibrated with those obtained by gravimetric method. The soil moisture profiles along depth and at different times are obtained and the exact position of the wetting front in the soil has been computed. The results provided can be used for further reference or validation of numerical modelling.

^ccr5 illus, 8 ref

002415   Singh V N;Mittal A (Dep of Earth Sci, Indian Inst of Technol, Roorkee-247 667, Email: abham2003@yahoo.com) : Synthetic accelerograms for two Himalayan earthquakes using convolution. Curr Sci 2005, 88(8), 1289-97.

In the communication, computation of synthetic accelerograms is based on convolution. The spectrum of ground motion expected at a recording site is first computed from a knowledge of source parameters and medium properties. This spectrum is then inverse Fourier transformed to yield the desired synthetic accel erogram. The method has been successfully used by Boore, and has been further extended in the communication. The suitability of the method is demon strated successfully by modelling the accelerograms for two Himalayan earthquakes namely, the 1991 Uttarkashi earthquake and the 1999 Chamoli earthquake and compared with the observed accelerograms.

4 illus, 4 tables, 23 ref

002414   Singh O P;Bhattacharya P M (Cent Geophysics Div, Geol Surv of India, 27, J L Nehru Road, Kolkata-700 016, Email: op_singh9@hotmail.com) : Seismic velocities and crustal structure beneath the Shillong Plateau, Mikir hills and Naga thrust zone in Northeastern India. J Geol Soc India 2005, 65(6), 715-24.

Sudy of travel times for the P_g, P^* and p_n waves is conducted selecting three traverses over the Shillong Plateau, Mikir Hills and Naga Thrust zone respectively in the Northeast India region. Seismic velocities and thickness of the upper crust, lower crust and depth to the Mono are estimated. These traverses are selected through the location of the maximum number of seismic stations and the epicentres of the earthquakes in the study area. About 136 earthquakes, with magnitude range 2.0-5.0 and depth range 5-30 km, recorded during the period 1986-1999 are used. The P_g, P^* and P_n velocities (km/sec) are estimated to be 6.04-6.21, 6.51 -6.62 and 8.47-8, 65 respectively in the region. The corresponding thickness (km) of the upper crust, lower crust and depth of the Moho are 16-19, 27-30 and 40-50, respectively. The presence of high Pn wave velocity (8.47-8.65 km/sec) in the region is possibly representing a colder and denser lithosphere.

7 illus, 3 tables, 21 ref