015592   Sunder Raju P V (NO, Natn Geophys Res Inst, Hyderabad-500 007) : Comparison of different extraction methods to determine gold in geological samples. J scient ind Res 2006, 65(1), 65-7.

Different petro-chemically varied lithological samples were collected from the Chitradurga schist belt, Karnataka, to identity auriferous zones. The efficiencies of gold estimation at very low levels by different extraction methods were compared. The extraction methods were fire-assay (FA), cyanide leach, and methyl isobutyl ketone (MIBK) solvent extraction. The rock samples include banded iron formations (silicate, oxides, carbonate and sulphide facies), ferruginous cherts, massive milky white quartz veins and highly sheared fractured translucent dark grey to bluish grey quartz veins. After separation and pre-concentration of gold, MIBK solvent extraction procedures have been studied using flame atomic absorption spectrophotometer (F-AAS).

2 tables, 6 ref

015591   Poroshin V D;Mulyak V V;Morozov A G;Khaynak V P (NO, , ) : Hydrochemical control of oil pool development (Illustrated with belarusian oil fields) Part IV. Indian J Petrol Geol 2005, 14(1), 97-9.

2 ref

015590   Pirasteh S;Ziaian H R;Rizvi S M A (Remote Sens and GIS, Civ Engng Dep, Islamic Azad University of Dezful, Dezful Iran, Email: moshaver13yahoo.co.in) : Comparative study of OIF and Crosta methods on ETM+2002: using remote sensing techniques in arid and semi-arid environment Esfahan. Indian J Petrol Geol 2005, 14(1), 67-79.

Principal component analysis is a well known method of orthogonalizing data. It converges very fast and the theoretical method is well understood. Basically image processing is used for extraction of required information. The present study begins with remote sensing techniques and PCA applying on enhance thematic mapper (ETM+) satellite image dated 2002 for central of Iran, west Esfahan city. The study presents two methods of enhancing igneous body consists of amphibolites and volcanic using optimum index factor (OIF) and Crosta. In this study the optimum index factor allows to use the multi-spectral data for understanding the best false color composite (FCC) image. It is also highlighted the required spectral range (bands) for classification of image to enhance the igneous bodies. The Crosta technique is based on PCA using eigenvector, enhanced the spectral behavior of minerals. The objects on the image are enhanced in terms of black and white with respect to eigenvector loading. 27 FCC images are produced and analyzed using OIF. It is seen that the classification on FCC images for bands 741 and 541 of Infra-red and FCC images for band 654 and 641 of Thermal infra-red are the most accurate composite color images to enhance igneous body, amphibole and clay minerals. The study reveals that the PC3 is increasing the enhancement for reorganization of amphibole minerals in orthoamphibolite rocks. It also shows that PC5 has suitable enhancement to identify the clay minerals in granite rocks. However the study also indicates the use of optimum index factor for identification of spectral bands to give more information about minerals on the image using classification techniques in arid and semi-arid environment where vegetation cover is scanty. This study also represents the use of remote sensing techniques for exploration.

9 illus, 3 tables, 16 ref

015589   Philip G;Mathew J (NO, Wadia Inst of Himalayan Geol, 33 Gen. Mahadeo Singh Road, Dehradun-248 001) : Climato-tectonic impression on Trans Himalayan lakes: A case study of Kyun Tso basin of the Indus Suture Zone in NW Himalaya using remote sensing techniques. Curr Sci 2005, 89(11), 1941-7.

Formation of lakes, regarded as the crown stage development of an erogenic belt, is an impressive geomorphic feature that adorns the Himalayan belt, end to end. The Kyun Tso is one such ancient twin lake system that lies to the south of the Indus Suture Zone in NW Himalaya. Authors has mapped the former extent of these lakes using remote sensing techniques in an attempt to understand the palaeohydrological conditions under which these water bodies developed. It has been observed that the dimensions of these lakes invariably fluctuated over time due to ongoing compression in the collisional regime and climatic fluctuations that have been recorded globally. The study also provides an opportunity to evaluate the utility of high spatial resolution Indian Remote Sensing Satellite (IRS) data for geological and geomorphological studies in arid, inaccessible and arduous terrain like the north-western Trans Himalaya.

5 illus, 1 table, 17 ref

015588   Nagendra R;Kamalak Kannan B V;Sajith C;Sen G; Reddy A N;Srinivasalu S (Dep of Geol, Anna Univ, Chennai-600 025) : Record of foraminiferal assemblage in tsunami sediments along Nagappattinam coast, Tamil Nadu. Curr Sci 2005, 89(11), 1947-52.

Study documents the assemblages of foraminifera and its distribution pattern in the tsunami inundation areas of Nagappattinam coast. The maximum inundation locations were chosen on the tsunami-hit Nagappattinam coast (Vilundamavadi, Kameshwaram, Velankanni and Nagappattinam) for faunal documentation. A total of 22 species belonging to 15 genera of benthic and one species of planktic foraminifera are identified in the tsunami sediments. Q-mode cluster analysis was carried out to understand the distribution pattern, which inferred five biotopes. This preliminary work on foraminiferal distribution infers that the benthic foraminiferal assemblages recorded in tsunami sediments are habitat of coastal to inner shelf environment.

7 illus, 1 table, 7 ref

015587   Murty C V R (Indian, Inst of Technol Kanpur, Kanpur-208 016, Email: eqtips@iitk.ac.in) : Learning earthquake design and construction 24. how to reduce earthquake effects on buildings?. Resonance 2005, 10(11), 89-92.

3 illus, 3 ref

015586   Murty C V R (NO, Indian Inst of Technol, Kanpur-208 016, Email: eqtips@iitk.ac.in) : Learning earthquake design and construction 23, why are buildings with shear walls preferred in seismic regions. Resonance 2005, 10(11), 85-8.

4 illus, 2 ref

015585   Mathur R;Balaram V;Suresh Babu S (Geochemistry Grp, Natn Geophys Res Inst, Hyderabad-500 007, Email: mathurramavati@yahoo.com) : Determination of mercury in geological samples by cold vapour atomic absorption spectrometric technique. Indian J Chem-Sect A 2005, 44(8), 1619-24.

Method for determination of total mercury in geological samples using acid digestion and subsequent measurement by cold vapour atomic absorption spectrometric technique is described. Sample digestion has been carried out using a combination of hydrochloric and nitric acids followed by reduction of mercury (II) in the extract to its elemental form by stannous chloride. The absorption signal at 253.7 nm has been monitored with a mercury analyzer. The method is simple, cost effective and gives reliable results as indicated by the data obtained on a few international geochemical reference samples, analyzed in this study. Precision of the measurements is within 5% RSD for closed vessel digestion. The detection limit of mercury is found to be 5 ng when 1 ml of 1% sample solution is utilized. Comparison of data obtained for the same set of standards using both open vessel and closed Savillex pressure decomposition vessel digestions demonstrates enhanced extraction in several cases while using closed vessel digestion. Results indicate that the method can be applied for determination of low levels of mercury in a variety of geological samples for exploration studies.

^ssc1 illus, 2 tables, 41 ref

015584   Marvin Herndon J (NO, Transdyne Corporation, 11044 Red Rock Drive, San Diego, CA-92131, USA) : Whole-earth decompression dynamics. Curr Sci 2005, 89(11), 1937-41.

Principles of whole-earth decompression dynamics are disclosed leading to a new way to interpret whole-earth dynamics. Whole-earth decompression dynamics incorporates elements of and unifies the two seemingly divergent dominant theories of continental displacement, plate tectonics theory and earth expansion theory. Whole-earth decompression is the consequence of earth formation from within a Jupiter-like protoplanet, with subsequent loss of gases and ices and concomitant rebounding. The initial whole-earth decompression is expected to result in a global system of major primary decompression cracks appearing in the rigid crust, which persist as the basalt feeders for the global, mid-oceanic ridge system. As the earth subsequently decompresses, the area of the earth's surface increases by the formation of secondary decompression cracks, often located near the continental margins, presently identified as oceanic trenches. These secondary decompression cracks are subsequently in-filled with basalt, extruded from the mid-oceanic ridges, which traverses the ocean floor by gravitational creep, ultimately plunging into secondary decompression cracks, emulating subduction. Much of the evidence presented in support of plate tectonics supports whole-earth decompression dynamics, but without necessitating mantle convection/circulation or basalt recycling. Moreover, unlike in earth expansion theory, the timescale for earth decompression is not constrained to the last 200 million years, the maximum age of the current ocean floor.

50 ref

015583   Laskar S K;Choudhury P (NO, Tezpur Univ, Napaam, Assam-784 028, Email: skl@tezu.ernet.in) : Downward continuation of two-dimensional potential field to a concave lower boundary. Indian J Petrol Geol 2005, 14(1), 41-66.

Down-continuation of two-dimensional potential field data from a datum line to a concave lower boundary with its arms extending along the datum line is achieved. On formulating the problem in an integral equation of the first kind in double layer density belonging to the continuation boundary in terms of data specified over the datum line, the equation is solved for a stable approximate density and the field on it is computed as its potential. For an analytical input field, it is theoretically shown that there exists a unique solution on the continuation boundary. For the input data with error, a method of successive correction of an initial choice is described that yields a stable approximate solution of the problem. Model studies are carried out to achieve the results numerically. It is shown that for the synthetic input data, the solution of the equation closely agrees with the Dirichlet density on the continuation boundary and for "the input data with error, the down-continued field appears with error commensurate with that in the input data.

1 illus, 2 tables, 16 ref

015582   Krishna Kumar G V;Balasubramanian P (NO, Nav Phys and Oceanographic Lab, Thrikkakara, Kochi-682 021) : IWAVE: an ocean simulation model for internal waves. Curr Sci 2005, 89(11), 1927-32.

Effective usage of scarce resources (ships, instruments, etc.) requires a coherent and rational approach to develop any underwater system. One of the important tasks towards achieving this is to simulate the performance of the proposed system under all oceanic conditions before it is being developed. Internal waves (IWs) play a major role in ocean thermodynamics, underwater acoustic transmission, etc. In order to understand the behaviour of IWs and their role in various physical processes in the ocean, authors has developed an IW model, IWAVE based on the Garrett-Munk modal spectrum. In the communication presented detailed implementation procedures of the model and also a technique to solve the eigenvalue problem accurately. An algorithm based on central finite difference and QR techniques was implemented to find the eigen-wave-numbers and modes (dispersion relations). IWAVE simulates temperature and salinity (estimated sound speed also) structure due to IWs in the ocean. Experiments were conducted to validate the model off the west coast of India. Variances of the measured and simulated sound speed are in good agreement.

4 illus, 1 table, 14 ref

015581   Kamesh Raju K A (NO, Natn Inst of Oceanography, Dona Paula-403 004) : Three-phase tectonic evolution of the Andaman backarc basin. Curr Sci 2005, 89(11), 1932-7.

Three-phase evolutionary scheme since Late Oligocene for the Andaman backarc basin has been proposed based on the multibeam swath bathymetry, magnetic and seismological data. A SW-NE trending spreading ridge bisects the basin. The tectonic evolution of the Andaman basin with special reference to the formation of oceanic crust within the backarc basin encompassing the backarc spreading, suggests a phase of ridge propagation. Swath bathymetry data documented topographic fabric of the ridge propagation and reveal several morphotectonic features that divide the basin into a complex western part comprising arc-parallel seamount chains, N-S trending fault systems and a relatively smooth eastern part. Spreading centre jump during Late Oligocene, rifting and extension during Middle Miocene to Early Pliocene followed by the recent true seafloor spreading since last 4 Ma define the three-phase tectonic evolution of the Andaman backarc basin. The recent phase has experienced westward propagation of the spreading centre. It has been suggested that ridge propagation modulated the crust. A schematic evolutionary sequence of the Andaman backarc basin has also been presented.

3 illus, 19 ref

015580   Joseph P V;Chacko J (Dep of Chem Oceanography, Sch of Mar Sci Cochin Univ of Sci and Technol, Cochin-682 016, Email: jchacko@cusat.ac.in) : Distribution of dissolved and particulate heavy metals in Chitrapuzha - a tropical tidal river, Kerala, India. Pollut Res 2005, 24(3), 513-21.

Temporal and spatial distributions of dissolved and particulate heavy metals in Chitrapuzha River (Kerala) were studied. The observed order of abundance of metals in dissolved phase was Fe <62> Zn <62> Mn <62> Pb <62> Cu <62> Cd whereas the same in particulate was Fe <62> Mn <62> Zn <62> Pb <62> Cu <62> Cd. All metals exhibited pronounced seasonal and spatial variations. A significant inverse relationship was observed between metal concentration and salinity. The abundance of all the trace metals studied was high in the industrial zone of Chitrapuzha river. Quantification of trace metal enrichment in the dissolved phase was attempted by calculating the enrichment factor, selecting Fe as the normalizing constituent. Trace metals were found enriched throughout the study area but in varying proportions. Contamination was found to be severe in the industrial zone.

17 illus, 3 tables, 22 ref

015579   Jeevankumar S;Banerjee S (Earth Sci Dep, IIT Bombay, Powai, Mumbai-400 076, Email: santanu@iitb.ac.in) : Facies, microbial features and paleogeography of the Kajrahat limestone in the eastern son valley. Indian J Petrol Geol 2005, 14(1), 81-96.

Paleoproterozoic Kajrahat Limestone in its type area is almost entirely constituted by microbially mediated sediments. Detailed field and microscopic investigations reveal three divisions within it. The lower division consists of three fades, via, black shale, crinkle laminated dolomite and planar laminated dolomite facies. It represents offshore depositional setting. The middle division is dominated by wavy laminated dolomite facies of microbial origin deposited in inner shelf and represents shallower bathymetry than the lower division. The upper division comprises of stromatolite, microbial laminite and thrombolite facies which represents deposition in subtidal to supratidal condition. Emergence features have been recorded near the top of the upper division. The Kajrahat Limestone represents overall shallowing, the lower division represents a condensed zone and the upper two divisions, together form a high stand systems tract.

12 illus, 41 ref

015578   Jain S L;Ghude S D;Arya B C;Ashok Kumar;Bajaj M M (Radio and Atmospheric Sci Div, Natn Phys Lab, New Delhi-110 012) : Signature of increasing total column water vapour and surface temperature at Maitri, Antarctica. Curr Sci 2005, 89(11), 1917-22.

Measurement of total column water vapour has been carried out at Maitri (70°45'S, 11°44'E), Antarctica using Microtop sun-photometer during the 16th, 21st, 22nd and 23rd Indian Antarctic Scientific Expedition. The annual mean water vapour was found out to be 0.24 cm in 1997, while it was 0.42 cm in 2002 and 0.45 cm in 2003. Monthly mean water vapour was maximum during January in all years studied and increased by 48.8% in 2002, 57.7% in 2003 and 66.6% in 2004, compared to 1997. Total column water vapour corresponding to surface temperature has also been studied. Years 2002 and 2003 were found to be warmer by 11.72 and 4.1% respectively compared to the year 1997. The observation showed signature of increasing total column water vapour at Maitri. Measurement also showed increase in surface temperature and was especially pronounced in the month of January at Maitri. In the communication, a comparative study of water vapour and surface temperature has been discussed in detail.

25 ref

015577   Gupta K;Jain S (NO, Regional Remote Sens Serv Cent, Dehradun-248 001) : Enhanced capabilities of IRS P6 LISS IV sensor for urban mapping. Curr Sci 2005, 89(11), 1805-12.

Attempt has been made to evaluate the information content available in IRS P6 LISS IV data for the identification of urban features and urban mapping. Level-III of the urban land use classification at the scale of 1:10,000 was successfully attempted for Dehradun city and its environs. A qualitative and quantitative evaluation of IRS P6 LISS IV data has also been done with PAN-sharpened LISS III data. The boundaries of polygon features, road intersections, contrast with the surroundings are more precise on LISS IV data in comparison to merged data. It is also found that 100% more linear features can be extracted with IRS P6 LISS IV data compared to PAN-sharpened LISS III product.

5 illus, 4 tables, 10 ref

015576   Ernest Raj P;Bhardwaj S (NO, Indian Inst of Trop Meteorology, Pashan Road, Pune-411 008, Email: ernest@tropmet.res.in ) : Spatial variation of aerosol mode radius retrieved from satellite - based atmospheric extinction measurements. Pollut Res 2005, 24(3), 499-504.

Aerosol extinction at two wavelengths from the available SAGE satellite measurements made during 1981 has been analyzed to retrieve vertical profiles of aerosol mode radius in 10-degree latitude bands in both the Northern and Southern hemispheres. Results show that mode sizes are largest in the equatorial upper troposphere and lower stratosphere. On a seasonal scale, they are large in the spring season. The observed variations in mode radius as a function altitude and latitude support the idea of an equatorial source of aerosols with larger radii in the equatorial region and sloping off towards the poles following the tropooause height. Influence of volcanic activity on spatial distributions of aerosol mode radius has also been observed in the study.

5 illus, 12 ref

015575   Biswas S K (K.D. Malviya Inst of Petrol Explor, ONGC, Dehradun) : Tectonic style and sediment dynamics of rifted basins, their bearing on petroleum habitat-examples from satpura and Kutch basins, India. Indian J Petrol Geol 2005, 14(1), 1-29.

Pericratonic rift basins, Intra-cratonic rift basins, Aulacogens (failed arms of triple junction) and Trans-tensional rift (pull-apart) basins are the main types of rifted basins. Rifting process consists of four stages of development - Early Rift, Rift Climax, Late Rift and Post-rift. In pericratonic situation rift-drift transition, (proto-oceanic) and post-rift oceanic stages follow the early rift stage when the rift is flooded by marine transgression after slope change with ocean ward tilt. Post-rift transgressive deposits over syn-rift basin-fill are common in the pericratonic rifts. In intracratonic set up the basin-fill sediments are deposited by dynamic relationship between footwall alluvial fan and hanging wall cones over basin central lakes in an interior drainage system and/or axial through drainage system. The sediment dynamics in this case are controlled by two fundamental slopes, a low gradient hanging wall dip slope with broad alluvial cones and a high gradient footwall slope, which sources small alluvial fans deposited close to the scarp. The cone-lake-fan triplet systems have particularly dynamic inter-actions at their boundaries. The Gondwana basins e.g., Satpura, Rewa and Damodar.

17 illus, 27 ref

015574   Bhattacharyya R;Majumdar T J (Earth Sci and Hydrology Div Mar and Wat Resour Grp, Space Applic Centere (ISRO), Remote Sensing Image Processing and Application Area, Ahmedabad-380 015, Email: tjmajumdar@sac.isro.org) : Utilisation of satellite altimeter data for offshore exploration with special reference to Bombay high coalfields, Jharkhand, India. Indian J Petrol Geol 2005, 14(1), 31-40.

Methodology had been developed and tested for generation of marine geoid and then residual geoids using ERS-1/Geosat/TOPEX altimeter data and Rapp's coefficients. Later, a prospecting geoidal map has been generated over a part of the western Indian offshore from the residual geoid map and the available bathymetry. A number of megastructures have been successfully interpreted in the study area e.g. Bombay High, Saurashtra platform, Laccadive ridge, Laxmi ridge etc. from this prospecting geoid map, which has been found very useful for offshore hydrocarbon-bearing structure delineation. In addition, very high resolution satellite-derived gravity data have been utilized over the Bombay High region showing marked improvement for the interpretation of the oil fields in this region.

6 illus, 24 ref

015573   Amit Kumar (NO, Natn Inst of Constr Mgmt and Res, Pune) : Impact of Tsunami on southeastern coast of India and redevelopment strategies. NICMAR J Constr Mgmt 2005, 20(4), 1-9.

Devastating impact of Tsunami that hit the South Eastern Coast of India and neighbouring region on the 26th December 2004 has left an unforgettable memory to its survivors. The magnitude of earthquake that generated the Tsunami waves in the Indian Ocean was as high as M 9.0, thereby resulting in severe loss to Indonesia, Thailand, India, Sri Lanka and Maldives. The preliminary study was conducted to understand the causes and impact of damage to built environment along the coast of Tami Nadu in India. Various aspects of losses and their impact have been studied and discussed in detail. In view of this unprecedented calamity and colossal damages, various sustainable redevelopment and rehabilitation strategies have been worked out.

12 illus, 2 tables, 10 ref

014597   Vishnoi B N;Virendra Singh (NO, Weather Radar Stn, Jaisalmer) : Wind analysis for wind power at Jaisalmer. Mausam 2005, 56(4), 904-7.

^ssc2 illus, 1 table, 5 ref

014596   Venkatanathan N;Rajeshwara Rao N;Sharma K K; Periakali P (Dep of Appl Geol, Univ of Madras, School of Earth & Atmospheric Sciences, Guindy Campus, A.C.College Buildings. Chennai-600 025, Email: physics16972@yahoo.com) : Planetary configuration: implications for earthquake prediction and occurrence in southern peninsular India. J Indian Geophys Union 2005, 9(4), 263-76.

Though there have been several attempts at earthquake prediction from different perspectives, this attempt aims at establishing planetary configurations as a definitive means of earthquake prediction. When two or more planets, Sun and Moon are aligned more or less in line (0ø or 180ø) with the Earth, then the Earth would be caught in the middle of a huge gravity struggle between the Sun and the planets. The gravitational stresses would change the speed of the Earth in its orbit and when the speed of rotation of the earth changes the tectonic plate motion also gets affected. The total angular momentum of planets involved in earthquake triggering mechanism can be calculated and the total force acting at the epicenter in a direction opposite to that of the earth's rotation can also be determined. At the epicenter, the speed of rotation of the earth can be calculated with the help of available software. So the planetary forces in the opposite direction to the rotation of earth act as a triggering mechanism for the accumulated stress at faults and plate boundaries to be released abruptly. This does not, however, mean that earthquakes will occur at all edges of the plate boundaries. Two of the parameters contributing to the triggering of an earthquake at a place are a) distance of epicenter from the planet position and b) direction of force acting at the possible epicenter. From the analysis of "significant earthquakes" over the past 100 years from all over the world and from Southern Peninsular India, the relationship between (i) latitude, longitude, and magnitude of the tremor and (ii) distance from the planet and direction of forces acting at any point can be inferred. Such inferences already made for different localities in other parts of world have unfolded an accuracy of more than 75% with regard to earthquake prediction.

5 illus, 3 tables, 53 ref

014595   Valdiya K S (NO, Jawaharlal Nehru Cent for Advd Scientific Res, Bangalore-560 064, Email: nehrucen@jncasr.ac.in) : Trans-Himadari fault: tectonics of a detachment system in central sector of Himalaya, India. J Geol Soc India 2005, 65(5), 537-52.

First recognized as the Malari Thrust Fault in northern Kumaun Himalaya in early seventies, as the South Tibetan Detachment System in southern Tibet adjoining northeastern Nepal in early eighties and as the Zanskar Shear Zone in northwestern Himachal Pradesh in late eighties, the fault between the high-grade metamorphic and granitic rocks of the Himadri (≡ Great Himalaya) and the Tethyan sedimentary pile, ranks in importance among the terrane-defining boundary thrusts like the Main Central Thrust (MCT) and the Main Boundary Thrust (MBT). Not only is there an abrupt change in the metamorphic grade across the tectonic plane, but also an attenuation and wholesale elimination of some lithostratigraphic formations of the hanging wall. Moreover, the strongly lineated metamorphic rocks of the basement complex in the footwall, characterized by isoclinal reclined folds, give way in the hanging wall to the Tethyan sedimentary rocks lacking in similar deformation and metamorphism. Later movements have caused shearing and brecciation of the basement rocks. Exhibiting predominant dip-slip movement in the central sector of the Himalayan arc, the Trans-Himadri Fault (T-HF) was formed as a consequence of the Tethyan sedimentary cover detaching from its rigid foundation of the basement complex, following blocking or slowing down on India-Asia collision zone of tectonic movements related to India-Asia convergence. As the basement complex was squeezed up to great height during a phase of compression, the sedimentary cover on the over-steepened northern slope of the Himadri slid down, toppling over northward and giving rise to back-folds and back-thrusts. In the compressive regime, there was strike-slip movement and attendant extension parallel to the orogen in eastern and western sectors of the Himalaya. In Kashmir, western Himachal Pradesh, central Nepal and northwestern Bhutan the compression was so strong that the Tethyan sedimentary rocks along with a slice of the basement in the hanging wall advanced southwards across the Himadri and were emplaced as nappes and klippen even south of the Main Central Thrust. The T-HF movement occurred in the period 23.5 and 19.5 Ma, say approximately around 20.9 Ma. Quaternary reactivation resulted in river ponding and development of huge lakes such as the Garbyang palaeolake in the Kali valley and the <126> 40,000 year old Goting palaeolake in the Western Dhauli valley.

11 illus, 73 ref

014594   Thamban M;Naik S S;Mohan R;Rajakumar A; Basavaiah N;D'Souza W;Kerkar S;Subramaniam M;Sudhakar M;Pandey P C (NO, Natn Cent for Antarctic and Ocean Res, Headland Sada, Goa-403 804, Email: meloth@ncaor.org) : Changes in the source and transport mechanism of terrigenous input to the Indian sector of Southern Ocean during the late Quaternary and its palaeoceanographic implications. J Earth Syst Sci 2005, 114(5), 443-52.

Changes in the terrigenous sediment source and transport mechanisms during the late Quaternary have been investigated using four sediment cores within the Indian sector of Southern Ocean, using the magnetic susceptibility (MS) and sedimentological records. Sediments deposited during the Holocene and other interglacial periods were characterised by low MS, low sand content, reduced ice-rafted detritus (IRD) input and increased illite possibly transported via hydrographic advection from the south. The glacial intervals are characterised by high MS, high sand content, increased IRD input and reduced illite clays, derived from both local as well as Antarctic sources. Significant reduction in clay fraction and illite content during glacials suggests that the erosive and transporting capabilities of the deep and bottom waters could have reduced compared to the interglacial times. The changes in terrigenous influx to this region were significantly influenced by the rhythmic glacial-interglacial fluctuations in bottom circulation and the position of the Polar Front.

4 illus, 1 tables, 27 ref

014593   Tewari R C (Dep of Geol, D.S. Coll, Aligarh-202 601, Email: ram_tewari@yahoo.com) : Tectono-stratigraphic- sedimentary events in Gondwana succession of peninsular India. J Geol Soc India 2005, 65(5), 636-8.

Late Paleozoic-Mesozoic Gondwana sediments of Peninsular India are dominantly clastics characterised by glaciogenic rocks at base followed by coal measures and in turn overlain by red beds at top. Distinct lithofacies assemblages, depositional facies models, paleoslopes and texture and composition of sandstones evidently suggest three successive tectono-stratigraphic-sedimentary events of Early, Main and Late Gondwana facies during Gondwana sedimentation of Peninsular India.

^ssc1 table, 15 ref

014592   Sundar D;Shetye S R (Phys Oceanography Div, Natn Inst of Oceanography, Dona Paula, Goa-403 004) : Tides in the Mandovi and Zuari estuaries, Goa west coast of India. J Earth Syst Sci 2005, 114(5), 493-503.

Mandovi and Zuari are two estuaries located in Goa, west coast of India. Variation of water level in the estuaries was monitored for a month at 13 locations using tide-poles during March-April 2003. Analysis of this data has provided for the first time, characteristics of how tidal constituents vary in the narrow and shallow estuaries, typical of those found along the west coast of India. At a distance of 45 km from the mouth the tidal range increased in both estuaries by approximately 20%. The tidal range at the upstream end of the two channels at the stations dropped sharply because of the increase in elevation of the channels.

5 illus, 5 tables, 6 ref

014591   Sukhija B S (NO, Natn Geophys Res Inst, Hyderabad-500 007, Email: bssngri@rediffmail.com) : Understanding groundwater system for its sustainability. J Geol Soc India 2005, 65(5), 655-7.

^ssc1 illus, 3 tables, 13 ref

014590   Sri Niwas;Gupta P K;Gaur V K (Dep of Earth Sci, Indian Inst of Technol Roorkee, Roorkee-217 667) : Normalized impedance function and the straightforward inversion scheme for magnetotelluric data. J Earth Syst Sci 2005, 114(5), 523-31.

Paper investigates the performance of normalized response function obtained by normalizing the Cagniard impedance function by a suitable factor and then rotating the phase by 45° to make it purely real for homogeneous half-space and equal to the square root of the half-space resistivity. Two apparent resistivity functions based on respectively the real and imaginary parts of this response function are proposed. The apparent resistivity function using the real part contains almost the same information as that yielded by the Cagniard expression while the one using the imaginary part qualitatively works as an indicator of the number of interfaces in the earth model. The linear straightforward inversion scheme (SIS), developed by the authors employing the concept of equal penetration layers, has been used to validate the proposed apparent resistivity functions. For this purpose, several synthetic and field models have been examined. Five synthetic models are studied to establish the veracity of the new functions and two well-studied published field data sets are inverted through SIS for comparison. Authors noticed that the new function and SIS compliment each other and lead to better understanding of the data information and model resolution.

8 illus, 3 tables, 20 ref

014589   Singh A;Jha S;Patwardhan A (Shailesh J. Mehta Sch of Mgmt, Indian Inst of Technol Bombay, Mumbai-400 076) : Acceleration in temperature increase over India : an application of two-phase regression. Mausam 2005, 56(4), 795-802.

Key issue in climate change is the extent to which there are changes in climate variables that may be consistent with anthropogenically induced climate change. An attempt has been made to apply two-phase regression model to records of long term annual mean surface air temperature over India to examine whether there are any significant changes in the temperature trends across the country. Finds that most of the stations selected for the study, show an acceleration in temperature trends during the mid 1900's. Even though a considerable variation with regard to the specific change point year is seen however there appear to be common periods across the different stations. Further analysis of long duration temperature records may be useful in attributing these changes to the anthropogenic forcing or natural variability.

2 illus, 1 table, 25 ref

014588   Shenoi S S C, et al (NO, Natn Inst of Oceanography, Dona Paula, Goa-403 004) : Hydrography and water masses in the southeastern Arabian Sea during March-June 2003. J Earth Syst Sci 2005, 114(5), 475-91.

Paper describes the hydrographic observations in the southeastern Arabian Sea (SEAS) during two cruises carried out in March-June 2003 as part of the Arabian Sea Monsoon Experiment. The surface hydrography during March-April was dominated by the intrusion of low-salinity waters from the south; during May-June, the low-salinity waters were beginning to be replaced by the high-salinity waters from the north. There was considerable mixing at the bottom of the surface mixed layer, leading to interleaving of low-salinity and high-salinity layers. The flow paths constructed following the spatial patterns of salinity along the sections mimic those inferred from numerical models. Time-series measurements showed the presence of Persian Gulf and Red Sea Waters in the SEAS to be intermittent during both cruises: they appeared and disappeared during both the fortnight-long time series.

10 illus, 1 table, 40 ref

014587   Shankar D;Shenoi S S C;Nayak R K; Vlnayachandran P N;Nampoothiri G;Almedia A M;Michael G S;Ramesh Kumar M R;Sundar D;Sreejith O P (NO, Natn Inst of Oceanography, Dona Paula, Goa-403 004, Email: shankar@darya.nio.org) : Hydrography of the eastern Arabian Sea during summer monsoon 2002. J Earth Syst Sci 2005, 114(5), 459-74.

Hydrographic observations in the eastern Arabian Sea (EAS) during summer monsoon 2002 (during the first phase of the Arabian Sea Monsoon Experiment (ARMEX)) include two approximately fortnight-long CTD time series. A barrier layer was observed occasionally during the two time series. These ephemeral barrier layers were caused by in situ rainfall, and by advection of low-salinity (high-salinity) waters at the surface (below the surface mixed layer). These barrier layers were advected away from the source region by the West India Coastal Current and had no discernible effect on the sea surface temperature. The three high-salinity water masses, the Arabian Sea High Salinity Water (ASHSW), Persian Gulf Water (PGW), and Red Sea Water (RSW), and the Arabian Sea Salinity Minimum also exhibited intermittency: they appeared and disappeared during the time series. The concentration of the ASHSW, PGW, and RSW decreased equatorward, and that of the RSW also decreased offshore. The observations suggest that the RSW is advected equatorward along the continental slope off the Indian west coast.

7 ref

014586   Sastry R G;Gupta M (Dep of Earth Sci, IIT, Roorkee-247 667, Email: rgss1fes@iitr.ernet.in) : 2-D analytic signal application in electrical profiling problems. J Indian Geophys Union 2005, 9(4), 315-27.

A 2-D stabilized analytic signal algorithm (RESAS) is used in interpreting synthetic electrical profiling data due to 2-D resistive / conductive bodies of both closed and open geometries. For bodies of closed geometry, pole-pole profiles with buried current pole above body center are considered while for open geometries, pole-pole (Half-Wenner) / pole-dipole apparent resistivity profiles are opted for. The analytic signal parameters like, amplitude of the analytic signal (AAS), real (RIAS) and imaginary parts (IIAS) of complex analytic signal inverse are used in the analysis. Synthetic buried pole-pole data is generated by finite-difference based resistivity modeling algorithm and this data served as input to RESAS. The numerical models included conductive bodies of closed geometry (Prism in 2-layered earth medium and two inclined dyke model) and open geometry (a faulted bed and Horst-Graben model). Achieved results show that AAS generally meets the interpretation requirements; but analyses of RIAS and IIAS are needed either to confirm the lateral coordinates inferred by AAS or supplement such information in case AAS fails. For body corners with same lateral coordinates (bodies with vertical dips), analytical signal method fails in segregating them and ambiguity arises. Further, numerical results confirm that profiles of sufficient length are needed to image the lower corners of anomaly causative sources. The obtained results validate the proposed interpretation procedure.

6 illus, 5 tables, 18 ref

014585   Sastry R G;Chaudhary N;Israil M (Dep of Earth Sci, Indian Inst of Technol, Roorkee-247 667, Email: rgsslfes@iitr.ernet.in) : Is there a need for variable density option in making combined mass correction to gravity data acquired over high relief?. Curr Sci 2005, 88(2), 269-73.

Traditional gravity data processing involves terrain and Bouguer corrections with uniform density. However, inclusion of variable densities honouring surface geology in such corrections is a long-felt need. This matter assumes fundamental importance for gravity data acquired over high relief. So, improved Bouguer and terrain correction scheme is proposed and its utility is demonstrated on a gravity profile along Mahe-Sumdo-Tso Morari of Ladakh Himalaya. A maximum difference of about 50-70 mGal in the final Bouguer anomaly is observed between data processed through normal procedure with uniform Bouguer density (= 2.67 g/cm³) and those proposed with variable density. This underlines the importance of the proposed scheme.

4 illus, 1 table, 10 ref

014584   Sarma A A L N;Srinivas S (Meteorology & Oceanography Dep, Andhra Univ, Visakhapatnam-530 003, Email: aalnsarma_met@rediffmail.com) : Some aspects of the intensification of hydrologic cycle over India. J Indian Geophys Union 2005, 9(4), 299-313.

An attempt has been made to study and understand some of the aspects of hydrologic extremities in terms of prevalence of varied degrees of drought, humidness and climate shifts on all India basis through the revised water balance model during the monsoon period from 1901 to 1990. Trend aspects in seasonal All India aridity, humidness and climate shifts of the s-w monsoon period are studied compared to the march of Southern Oscillation (SO) Index and Sea Surface Temperature (SST) of NINO3 region. One of the important aspects of the investigation is the appraisal of the modulation of the basic water budget elements of All India during extreme dry and wet shifts of the s-w monsoon compared to normal and in the context of ElNino-Southern Oscillation (ENSO) signal. Also analyzes the mean monsoon seasonal flows of Krishna river basin at Vijayawada point along with its trend in relation to ElNino-Southern Oscillation (ENSO) and LaNina -Southern Oscillation (LNSO) signals. A comperative study of the frequency of cyclonic disturbances and storms in the Indian region during distinct epochs compared to normal and in the context of global warming is made. The investigation also address not only in approximating a third order polynomial fit for the number of storms and cyclones in the Indian region, but also the trend aspects for the study period from 1901 to 1990 in relation to short term climate signal.

11 illus, 3 tables, 27 ref

014583   Sarkar B C;Roy I (Dep of Appl Geol, Indian Sch of Mines, Dhanbad-826 041, Email: bhabesh_sarkar@hotmail.com) : A geostatistical approach to resource evaluation of Kalta iron ore deposit, Sundargarh district, Orissa. J Geol Soc India 2005, 65(5), 553-61.

A prime purpose of ore body modelling is to reliably estimate the distribution of in situ and recoverable tonnages and grades of a mineral deposit. Conventional methods of estimation, such as polygonal, triangular, cross-sectional and distance weighting provide local estimates of an ore body. However, such estimates are not error associated. Classical statistical techniques provide error of estimation but ignore spatial relationships. A thorough geostatistical estimation with careful attention to geology of mineralization provides not only an adequate global reserve estimate but also a more reliable block-by-block mineral inventory with associated confidence in the block estimates. Such estimates are crucial for short- and long-term planning for exploration of mineral deposits to maximise net return on investment. Kalta iron ore deposit, located in the state of Orissa, has been studied for resource evaluation using geostatistical approach taking into account the geological parameters wherever necessary. Using exploratory drill hole information, a study starting from statistical distribution modelling through semi-variography to generation of ore inventory and grade-tonnage relationships has been carried out to highlight the effectiveness of such modelling.

6 illus, 5 tables, 19 ref

014582   Saraswat R;Nigam R;Barreto L (Micropaleontology Lab, Natn Inst of Oceanography, Dona Paula-403 004) : Palaeoceanographic implications of abundance and mean proloculus diameter of benthic foraminiferal species Epistominella exigua in sub-surface sediments from distal Bay of Bengal fan. J Earth Syst Sci 2005, 114(5), 453-8.

Temporal variation in abundance and mean proloculus diameter of the benthic foraminiferal species Epistominella exigua has been reconstructed over the last <126> 50,000 yr BP, from a core collected from the distal Bay of Bengal fan, to assess its potential application in palaeoceanographic reconstruction studies. The down-core variation shows significant change in abundance of E. exigua during the last <126> 50,000 yr BP. In view of the present day abundance of this species from areas with strong seasonal organic matter supply, authors has concluded that at <126> 7, <126> 22, <126> 33 and <126> 46 kyr BP, strong seasonality prevailed in the distal Bay of Bengal fan, probably indicating either strong or prolonged north-east monsoon or weakened south-west monsoon. For the first time, a strong correlation is observed in abundance and mean proloculus diameter of E. exigua. Based on coherent variation in mean proloculus diameter and abundance, it is postulated that mean proloculus diameter can also be used to infer increased seasonality in organic matter production, thus variation in strength or duration of monsoon. Thus, the study establishes that the down-core variation in the abundance and mean proloculus diameter of Epistominella exigua can be used to infer past climatic variations from the distal Bay of Bengal fan.

3 illus, 29 ref

014581   Santosh Kumar;Pieru T;Rino V;Lyngdoh B C (Dep of Geol, Kumaun Univ, Nainital-263 002, Email: skyadavan@yahoo.com) : Microgranular enclaves in neoproterozoic granitoids of South Khasi hills, Meghalaya plateau, Northeast India, field evidence of interacting coeval mafic and felsic magmas. J Geol Soc India 2005, 65(5), 629-33.

Microgranular enclaves (ME) in south Khasi granitoids (SKG) are mesocratic to melanocratic, fine-to medium-grained and porphyritic, and occur abundantly between Mawthaphdah and Jashiar villages. The ME are 3 to 30 cm across, and their shapes vary from subrounded, ovoid, to ellipsoidal and show sharp and crenulate contacts with the SKG without deformational and or reaction signatures. The megascopic features of ME and their relationships with SKG reveal that mafic and felsic (SKG) magmas having some initial crystallinities co-existed, mixed and generated a hybrid (ME) magma. Minerals such as K-feldspar megacrysts, mafic and felsic xenocrysts were transferred and disequilibrated, and became corroded in the new hybrid magma. The hybrid magma further evolved as ME globules mingled and undercooled into relatively cooler SKG magma.

^ssc2 illus, 17 ref

014580   Ravi Shankar M N;Mohan G (Dep of Earth Sci, Indian Inst of Technol Bombay, Powai, Mumbai-400 076, Email: gmohan@iitb.ac.in) : GIS based hydrogeomorphic approach for identification of site-specific artificial-recharge techniques in the Deccan Volcanic Province. J Earth Syst Sci 2005, 114(5), 505-14.

Deccan Volcanic Province (DVP) of India, as a whole, faces a severe shortage of water despite receiving a high annual rainfall, this is primarily due to excess runoff and lack of water conservation practices. In the study, an attempt is made to identify zones favourable for the application and adaptation of site-specific artificial-recharge techniques for augmentation of groundwater through a Geographical Information System (GIS) based hydrogeomorphic approach in the Bhatsa and Kalu river basins of Thane district, in western DVP. The criteria adopted for the GIS analysis were based on the hydrogeomorphological characteristics of both basins extracted from the IRS-1C LISS-III data supported by information on drainage pattern, DEM derived slope, lineament density, drainage density, and groundwater condition. The integrated study helps design a suitable groundwater management plan for a basaltic terrain.

5 illus, 2 tables, 15 ref

014579   Raval U (NO, Natn Geophys Res Inst, Hyderabad, Email: naqvimahmood@yahoo.com) : Some factors responsible for the devastation in Nagapattinam region due to Tsunami of 26th December, 2004. J Geol Soc India 2005, 65(5), 647-9.

^ssc3 illus, 8 ref

014578   Rammana L V;Swamy K V;Visweswara Rao C (NO, Indian Inst of Geomagnetism, New Panvel, New Mumbai) : Deep crustal structure across Krishna-Godavari basin from gravity data. J Indian Geophys Union 2005, 9(4), 249-55.

Gravity data over the Krishna Godavari (KG) basin is reinterpreted primarily for attributing the causative source for the conspicuous gravity high over the southeastern side of the Tanuku horst, namely, Kakinada Terrace (KT). Three-layered crust is assumed based on DSS studies in this region. Using the available gravity data the crust is modeled along two profiles as a three-layered unit. Densities of layers required in this modeling are determined on the basis of seismic P wave velocity ranges and well log data. The models are constrained with available depth values of the basement at some places along the profiles. The resulted model supports a basement of high-density of 2.90 gm/cc below the KT instead of Archean igneous and metamorphic basement with a density of 2.76 gm/cc. In other parts of the basin this denser layer is traced below the usual Archean basement complex. Different densities and seismic wave velocities characterize these two layers with a boundary between the two terminating in KT region. A denser basement in the KT region is perhaps due to the subsidence of sedimentary sequences in southeastern parts of East Godavari sub basin that may have contributed a steep step fault zone in Paleocene basalts, known as Matyapuri -Palakollu Fault Zone (MPFZ) and subsequent tectonic readjustment. The interpretation also rules out a Moho rise below this region supporting the conclusion arrived at by DSS studies in this region.

3 illus, 20 ref

014577   Ramalingam K;Sashibushana Rao G;Somasekhra Rao P V D;Sharma A D (NO, Airports Auth of India, Hyderabad-500 016) : GPS satellite and receiver instrumental biases estimation using linear adaptive filter algorithm. J Indian Geophys Union 2005, 9(4), 255-62.

The Category I (CAT I) Precision Approach (PA) requirements can be achieved by augmenting the Global Positioning System (GPS). The space based augmentation system (SBAS) in India is known as GPS And Geo Augmented Navigation (GAGAN). One of the prominent errors in GAGAN that limit the positional accuracy is instrumental biases. Calibration of these biases is particularly important in achieving the CAT I PA landings. A new algorithm is proposed to estimate the instrumental biases by modelling the TEC using 4th order polynomial. The algorithm uses values corresponding to a single station for a 12 day period and the results confirm the validity of the algorithm. The experimental results indicate that the estimation precision of the satellite-plus-receiver instrumental bias is of the order of ñ0.17nsec. The observed mean bias error is of the order -3.638nsec and -4.71nsec for satellite 1 and 31 respectively. It is found that results are consistent over the period.

6 illus, 1 table, 11 ref

014576   Prasad S;Khan E A (NO, Geol Surv of India, Sector-E, Aliganj, Lucknow-226 024, Email: surendra_gsilko@yahoo.com.in) : Gandak fan - a macro quaternary feature of middle Ganga plain, Uttar Pradesh and Bihar. J Geol Soc India 2005, 65(5), 597-608.

Gandak fan, is a large lobate feature trending in NW-SE direction, restricted between the fluvial regimes of Little Gandak in the west and Burhi Gandak in the east, in parts of eastern Uttar Pradesh and north Bihar. It is characterised by distinct geomorphology, manifested by clusters of tals, palaeochannels, oxbow lakes and spill over channels left out by a past history of river migration and flash floods of Gandak and its predecessors. The terrain is characterised by wide spread drapes of newer alluvium sediments locally known as Bhat Alluvium forming a calcareous, fine sandy to silty soil. Granulometric properties of the sand sequence associated with this unit indicate dominance of very fine grained sand with median value of 3.0 phi. The clay mineral study of this soil unit indicates preponderance of calcite mineral (30%) besides illite, chlorite and muscovite. Based on the analysis and synthesis of data, an attempt has been made to interpret the morphology of Gandak fan and the genesis of widespread occurrences of Bhat Alluvium of this region. The model envisaged for the formation of the fan dwells on possible cataclasmic neotectonic events related to Gandak Tear and other structures in the vicinity. The neotectonic event triggered widespread river migration/avulsion and cascades of mud flows released from breach and spill over of some large lacustrine bodies formed earlier by damming of the river course in the Jhawani Valley in upstream of Gandak catchment area in Nepal. In addition, the geological and geomorphological set up of Gandak Fan has also relevance to environmental scenario of the area especially to the perpetual floods in large tracts of north Bihar. It is also surmised that the cascades of mudflows related in the formation of fan and rampant floods in the area might be the causative factors for burial of many important temples and monasteries of Buddhist period, such as Kushinagar, Vaishali, Lauria, etc.

3 illus, 5 tables, 32 ref

014575   Prasad A S S S R S;Vankateswarlu N;Reddy P R (NO, Natn Geophys Res Inst, Hyderabad-500 007) : Crustal density model along Gopali- port canning profile West Bengal basin using seismic gravity data. J Indian Geophys Union 2005, 9(4), 235-9.

An integrated approach of processing and interpretation of the seismic, gravity, geological and structural details along Gopali- Port Canning Deep Seismic Sounding (DSS) profile, West Bengal basin has helped in deriving a crustal density model. This model clearly explains the trend, shape and magnitude of the Bouguer gravity anomalies across southern parts of the West Bengal basin. The study pointed out that the thick sedimentary column (thickening towards east) and lateral structural variations in the middle and lower crustal layers coupled with structural trends in the basement have jointly contributed to gravity effect. The prominent lateral variations in the Bouguer gravity anomalies could mainly be attributed to regionally extending causative factors. The derived model is useful in understanding the complex structural trends of geodynamic importance.

5 illus, 19 ref

014574   Pattanaik D R;Kalsi S R;Hatwar H R (NO, India Meteorological Dep, New Delhi-110 003) : Evolution of convection anomalies over the Indo-Pacific region in relation to Indian monsoon rainfall. Mausam 2005, 56(4), 811-24.

Attempts to explore a relationship between Indian Summer Monsoon Rainfall (ISMR) and the evolution of convective activity during winter to pre-monsoon seasons over the Indo-Pacific region. The monthly mean Outgoing Long-wave Radiation (OLR) data obtained from National Oceanic and Atmospheric Administration (NOAA) polar orbiting spacecraft are used in this study from January 1975 to May 2004. It is observed that the negative OLR (thus, convection) anomalies from January gradually strengthen in a west northwest direction from western Pacific region and got established over the southeast Asian region and adjoining eastern equatorial Indian Ocean by the month of May during excess ISMR years indicating a gradual reversal of anomalous rising motion over western Pacific in January to anomalous sinking motion in May over western Pacific region. However, during the deficient ISMR years the negative OLR anomalies established over the western Pacific region in January almost remain active over the same region till the month of May and consequently there is persistent presence of rising motion from northern winter to pre-monsoon seasons over the western Pacific. Similar to the patterns during the deficient composite the evolution of OLR anomalies show stronger than normal convective activity over the western Pacific region east of 150° E compared to that of eastern Indian Ocean and adjoining southeast Asia from February to May during the deficient years of 1979, 1982, 1987, 2002, and 2004 though there exists strong interannual variability in its magnitude. The tendency of OLR anomalies over the western Pacific region from January to March and the difference of OLR anomalies between western equatorial Pacific and eastern Indian Ocean and adjoining southeast Asia regions in the month of May shows significant (95% level) correlation with ISMR and the predicted ISMR with these two predictors using simple regression model shows significant correlations (95% and 99% level respectively) with actual ISMR for the extreme years.

10 illus, 22 ref

014573   Patel N R;Suresh Kumar;Pande L M (NO, Indian Inst of Remote Sens, 4, Kalidas road, Dehradun-248 001) : Quantification of water limited yield in rainfed crops using GIS based modelling. J appl Hydrol 2004, 17(2-3), 60-8.

Operational agricultural water management and scientific planning of limited water supply for rainfed agriculture mainly relies on real time scheduling of supplemental irrigation. Modern tools such as Remote sensing and Geographical Information System (GIS) have been used to extend capability of soil water crop modeling to a regional scale for spatial mapping of water deficit and relative yield potential in part of Suarna watershed. The soil-water-crop model used in the study for quantitative assessment of water limited yield potential constitutes both soil water balance according to criterion expressed by Thornthwaite and Mather (1955) and multiplicative form of Stewart's formula (Stewart and Haggam, 1973). The water limited productive potential so obtained were in the range of 50.2 to 67.3 % and 32.3 to 62 % of maximum yield potential for sugarcane and paddy, respectively. Whereas, yield levels of maize has not been so far limited due to in season water availability. This attempt would help better planning of economical irrigation applications and to support regional agrometeorological information to help farmer's decision on irrigation.

7 illus, 3 tables, 8 ref

014572   Parekh B B;Joshi M (Crystal Growth Laboratory. Dep of Phys, Saurashtra Univ, Rajkot-360 005) : Crystal growth and dissolution of brushite crystals by different concentration of citric acid solutions. Indian J pure appl Phys 2005, 43(9), 675-8.

Calcium hydrogen phosphate dihydrate (CHPD) or brushite crystals are well-known urinary crystals and frequently found in urinary stones. The CHPD crystals were grown by the single diffusion gel growth technique in sodium meta-silicate gel. The grown crystals were having platelet and star shape morphologies. The maximum growth was observed for the first five days, thereafter, the growth became almost steady. After achieving maximum growth of CHPD crystals, the aqueous solutions having different molar concentrations of citric acid were added into the supernatant solution containing calcium chloride. In the case of low concentrations of citric acid, the inhibition of the growth of CHPD crystals was observed, whereas for the higher concentrations of citric acid the dissolution of the grown crystals was observed. This indicates that the citric acid inhibits the growth of CHPD crystals in the lower concentrations and dissolves them in the higher concentrations. This supports the citrate inhibition theory of urinary calculi and crystals.

1 illus, 23 ref

014571   Panigrahy B K;Raymahashay B C (Civ Engng Dep, Kakatiya Inst of Technol and Sci, Warangal-550 601) : River water quality in weathered limestone: A case study in upper Mahanadi basin, India. J Earth Syst Sci 2005, 114(5), 533-43.

Stromatolitic limestone and calcareous shale belonging to Chattisgarh Supergroup of Proterozoic age dominate the upper part of the Mahanadi river basin. X-ray diffractogram (XRD) of limestone rocks show presence of a significant amount of calcite, dolomite and ankerite. Shales of various colours contain calcite and dolomite. It is observed that congruent dissolution of carbonate minerals in the Charmuria pure limestone has given rise to a typical karst topography. On the other hand, limestones are also seen to support red and black soil profiles. This indicates that the limestone bedrock undergoes a parallel incongruent weathering, which leaves a residue of decomposed rock. The XRD analyses reveal that the limestone soils thus formed contain an assemblage of quartz, clays and Fe-oxides. It is likely that the silicate component trapped during deposition of the stromatolitic limestone weathers incongruently resulting in diverse soil profiles. Carbonate and silicate mineral weathering schemes have been worked out to explain the soil formation, fixation of Al in clay minerals, and Fe in goethite. The water quality parameters such as Ca, Mg and HCO₃ in the river water suggest under saturation with respect to calcite and dolomite. The mineral stability diagrams indicate that kaolinite and Ca-smectite are stable in the river water environment, hence they occur in suspended sediments and soils. The dominant influence of carbonate weathering on the water quality is observed even in the downstream part of the river outside the limestone terrain.

7 illus, 8 tables, 24 ref

014570   Padgalwar K V;Prasad S K (NO, Meteorological Office, Pune-411 007) : Climatological features of tropical disturbances over the Indian Ocean - South of equator. Mausam 2005, 56(4), 779-84.

Attempt has been made to compile the different characteristics viz, genesis, dissipation and movement of tropical disturbances (depression stage onwards) over the Indian Ocean south of equator. These characteristics have been computed over a grid of 2.5° x 2.5° of Lat/Long. from equator to 40° S and between 35° E to 105° E. The study indicates an interesting feature regarding the formation of cyclone close to equator, between equator to 2.5° S in the month of December 1991. The annual frequency of tropical disturbances has been found to be 11.9 against the climatological normal of 8.4 as given by Gray. Interestingly, no tropical disturbance has been found to dissipate upto 5° S from equator and no disturbance has formed during the period in the latitudinal belt of 27.5° S to 40.0° S. It has been further seen that the frequency of westward (eastward) movement of tropical disturbances decreases (increases) from equator to 2.5° S and 32.5° S to 35.0° S. It is interesting to note that no tropical disturbance has shown eastward movement within equator to 2.5° S.

2 illus, 2 tables, 6 ref

014569   Oladosu O R;Jegede O O (Dep of Phys, Fedl Univ of Technol, PMB 704 Akure, Nigeria) : Variation of thermal properties in relation to the moisture content in a fine sandy-clay-loam soil at Ile-Ife, Nigeria. Mausam 2005, 56(4), 883-92.

The variation of soil thermal properties (for fine sandy-clay-loam/sandy-clay) with the amount of moisture in the top layer surface - 0.10 m, has been investigated at a tropical site in Ile-Ife, Nigeria (7° 33' N, 4° 34' E) between May and July, 2001. The micrometeorological parameters measured were surface (skin) temperature, soil water content, global and net radiation, as well as soil temperatures and heat flux at : 0.05 m, 0.10 m, 0.20 m, 0.30 m, 0.50 m, and 1.0 m depths. For soil water contents ranging between 15 and 25% in the top soil layer, 0.05-0.10 m (fine sandy-clay-loam), the mean values of the heat capacity, thermal diffusivity, thermal conductivity, and thermal admittance obtained were : (2.6 ± 0.2) x 10⁶ Jm^-3 K^-1, (0.4 ± 0.1) x 10⁶ m² s^-1, 1.1 ± 0.3 Wm^-1 K^-1, and 1.6 ± 0.3 Jm² s^-1 K^-1 respectively. In the bottom layer, 0.10-0.20m (sandy-clay soil), the respective values obtained were: (0.6 ± 0.1) x 10⁶ Jm^-3 K^-1, (0.9 ± 0.2) x 10^-6 m² s^-1, 0.5 ± 0.1 Wm^-1 k^-1 and 0.6 ± 0.2 Jm^-2 s^-1/2 k^-1. From the diurnal trends of the soil thermal parameters determined, the magnitudes showed strong association with the levels of the water content. The thermal diffusivity was found to increase with the amount of soil moisture, up to about 20% of the volumetric water content, but fell as the water content further increases. Similar patterns of the soil moisture levels were noticeable both for the thermal conductivity and admittance.

5 illus, 1 table, 17 ref

014568   Nath S K;Vyas M;Pal I;Singh A K;Mukherjee S; Sengupta P (Dep of Geol and Geophysics, Indian Inst of Technol, Kharagpur-721 302, Email: nath@gg.iitkgp.ernet.in) : Spectral attenuation models in the Sikkim Himalaya from the observed and simulated strong motion events in the region. Curr Sci 2005, 88(2), 295-303.

Strong motion recordings by the Sikkim Strong Motion Array (SSMA) of 80 events with good signal-to-background noise ratio (≥ 3) for magnitude between 3 to 5.6, have enabled estimation of source model and site response, and also the simulation of spectral acceleration for moderate-to-large earthquakes with 6 ≤ Mw ≤ 8.3. A combined simulated and recorded data set have ultimately been utilized for deriving the spectral attenuation laws incorporating the local site conditions, namely, topographic effect and site response, with and without shear wave velocity in addition to the normal earthquake parameters, viz. moment magnitude (Mw) and source-to-site distance (r). The spectral attenuation laws developed in the study have been found to be appropriate for predicting free-field horizontal Peak Ground Acceleration (PGA) for earthquakes of 3 ≤ Mw ≤ 8.3 and for the sites with distances up to 100 km from the source in the Sikkim Himalaya. The estimated spectral acceleration through these attenuation laws mimic the mean spectral acceleration simulated using Brune's source model.

7 illus, 26 ref