009863   Prasad T G;Ikeda M;Kumar S P (Div Ocean & Atrmospher, Hokkaido Univ, Grad Sch Environm Earth Sci, N-10, W-5, Sapporo,Hokkaido-0600810 Japan) : Seasonal spreading of the Persian Gulf Water mass in the Arabian Sea. Geophys Res-Oceans 2001, 106(C8), 17059-71.

Examination of the seasonal cycles of heat and freshwater fluxes in the Persian gulf region indicates that PGW forms as a result of elevated evaporative cooling in conjunction with reduced insolation during winter. Maps are presented of the distributions of depth, salinity, and geostrophic flow on sigma (theta) = 26.5, which nearly coincides with the core of the PGW. After intense mixing in the Strait of Hormuz, the property fields suggest that warm (<62> 17 degrees C) and high-salinity (<62> 36.2 psu) PGW enters the Arabian Sea to form a subsurface salinity extremum between 200 and 300 m. Found variability in the distribution of PGW in the Arabian Sea associated with monsoonal changes in the Arabian Sea circulation. During the winter monsoon, there is southward spreading of PGW along the western boundary; while during summer it is not present. Lateral mixing with low-salinity water from the Bay of Bengal in the region south of 10 degrees N and along the west coast of India during winter accounts for changes in the characteristics of PGW along these paths. Associated with the Findlater Jet during summer, the entire thermohaline structure is vertically displaced along the coasts of Somalia and Arabia. Ekman convergence in the central Arabian Sea accounts for deepening of the PGW. Either lateral or vertical mixing would cause changes in PGW : properties in these regions.

43 ref

009862   Patel S J;Desai B G (Department of Geology, M.S. University of Baroda, Vadodara-390 002) : Republic Day Kachchh earthquake of 2001 : Trauma in Oratosquilla striata. J Geol Soc India 2001, 58(3), 215-16.

2 illus, 9 ref

009861   Patel S C;Frost B R;Faizan I;Dey R;Ghosh T K (Department of Earth Sciences, Indian Institute of Technology, Bombay, Powai, Mumbai-400 076) : Metamorphism and contrasting corona structures in Bolangir Anorthositic rocks, Orissa. J Geol Soc India 2001, 57(1), 31-8.

Massif type anorthositic rocks in Bolangir area of the Eastern Ghats belt contain garnet porphyroblasts, which are surrounded by reaction coronas. The corona usually comprises a vermicular intergrowth, which in one instance consists of radial orthopyroxene and anorthite-rich plagioclase, and in another of radial chlorite and anorthite-rich plagioclase. Some of the anorthositic rocks are layered with thin discontinuous mafic layers of clinopyroxene and biotite. Notable is the presence of retrograde ferro-anthophyllite in the mafic layers of some of the rocks. Thermobarometric calculations using assemblage in the orthopyroxene corona indicate decompression from minimum peak P-T condition of 8 kbar and 700°C.

3 illus, 4 tables, 23 ref

009860   Pal N;Pal D C;Mishra B;Meyer F M (Dept Geol & Geophy, Indian Inst Technol, Kharagpur-721302) : Evolution of the Palim granite in the Bastar tin province, Central India. Miner Petrol 2001, 72(4), 281-304.

The Palim granite, hosted by the metasedimentary country rocks in the Bastar tin province, is a heterogeneous pluton that comprises hornblende granite, biotite granite and two-mica granite. Spherical inhomogeneous surmicaceous enclaves occur within the granites with coarse grained cores of muscovite mantled by finer muscovite-quartz-biotite ( sillimanite) rims. Geochemical features imply that the granites are highly evolved and geochemically distinct. Petrographic and geochemical considerations point towards a transition from metaluminous I type hornblende-bearing granite in the south to peraluminous volatile-enriched s-type like lithologies (biotite and two-mica granites) towards north. Modeling of highly incompatible elements such as Nb and Cs, implies 31 to 33% assimilated fractional crystallization of a melt with an initial composition close to that of the hornblende granite to form the two-mica granite. Hornblende geobarometry, plagioclase-hornblende thermometry (in hornblende granite) and phengite barometry (in two-mica granite), yield P-T estimates of 5-7 kb/725 degrees -760 degrees C, and kb/700 degrees C, respectively. The study further implies that a genetic link exists between granite magmatism and the formation of tin pegmatites in the region. The preponderance of peripheral gegmatites to the north-east of the Palim granite is regarded a result of outward crystal-melt fractionation and tectonic tilting of the pluton.

65 ref

009859   Manju C S;Nair V N;Lalithambika M (Reg Res Lab, Ind Estate PO, Trivandrum-695 019) : Mineralogy, geochemistry and utilization study of the Madayi kaolin deposit, north Kerala, India. Clays Clay Miner 2001, 19(4), 355-69.

For clay formation geochemical and morphological studies of different strata indicate : intense lateritized weathering conditions for kaolinization of the residual white clay from parent quartzo-felspathic mica-gneiss; reducing environment for the gray carbonaceous layers; and oxidizing environment for the uppermost hematite-rich ferruginous clay. Pyrite/marcasite enriched detrital gray carbonaceous clay shows two distinct environments for in situ kaolinite crystallization : within plant fossils influenced by the high organic content and FeS leaching; and precipitaiton from solution. Incomplete kaolinization of white residual clay is evident from the presence of pyrophyllite, muscovite with lenticular cleavage void and a lower percentage of fines (<60>2 pm). The plant fossils from the uppermost portion of residual clay show pyrite mineralization. The Hinckley Index, FTIR and rare earth analysis point towards diverse geochemical environments of deposition and technological evaluation indicates its suitability for application in the ceramics industry.

23 ref

009858   Maheshwari A;Sial A N;Mathur S C (Department of Geology, University of Rajasthan, Jaipur-302 004) : Carbon isotope oscillations through the Marwar supergroup, Western Rajasthan. J Geol Soc India 2001, 57(1), 83.

^ssc1 illus, 5 ref

009857   Kurothe R S;Challa O;Samra J S;Velayutham M (Research Centre, Central Soil & Water Conservation Research & Training Institute, Vasad-388 306) : Assessment of soil erosion in Maharashtra. Indian J Soil Conserv 2001, 29(2), 133-7.

Universal soil loss equation (USLE) was used to estimate soil loss from 2735 points on 10 x 10 km grid distributed over entire Maharashtra state of India. Various parameters of USLE were worked out by using information on rainfall, soil analysis, topography and land uses collected from various sources. The computed values of soil loss were grouped in seven classes. The results showed that soil loss in Maharashtra varies from very slight (<60>5 t ha^-1 yr^-1) in 45.65 per cent area to extremely severe (<62>80 t ha^-1 yr^-1) in 5.61 per cent area. The severity of erosion normally increased with rainfall and steepness of slope. High intensity rainfall received on hilly areas of Konkan coast and Western Ghat region produce relatively higher amount of soil loss. Parts of state under 5-10, 10-15, 15-20, 20-40 and 40-80 t ha^-1 yr^-1 soil loss category is in central and eastern region covering an area of 48.74 per cent in the state. Conservation measures and afforestation on the hilly slopes are called upon especially in high rainfall areas to conserve natural resources. Catchment areas of major reservoirs need immediate attention of soil and water conservation measures with active participation of all stakeholders. Areas with slight erosion also require intensive practices of water conservation to realize sustainable environmental and livelihood support..

1 table, 16 ref

009856   Krishnan R;Sugi M (Indian Inst Trop Meteorol, Dr Homi Bhabha Rd, NCL, Post, Pune-411008) : Baiu rainfall variability and associated monsoon teleconnections. J Met Soc 2001, 79(3), 851-60.

Century-long observations enable us to uncover an interesting out-of-phase variability between the first principal component of Baiu rainfall over the Japanese archipelago and the monsoon rainfall over India during the early summer season. The signatures of this contemporaneous relationship are clearly evident from analysis of long-period multi-source climate datasets. One of the findings suggest that the circulation near the subtropical region of the west Pacific Ocean tends to vary in-phase with that over the Indian subcontinent, so that an intensified (weakened) west Pacific subtropical high is accompanied by an intensified (weakened) Baiu circulation over Japan and a weakened monsoon circulation over India. Additionally, the Baiu-Indian Monsoon relationship is well supported by middle and upper tropospheric circulation anomalies extending from the mid-latitude region of West-Central Asia up to the Far East. A pattern consisting of an anomalous low over the Caspian and Aral Sea region, a high over Mongolia and an anomalous low over Korea and Japan, tends to be associated with increased Baiu rainfall over Japan and decreased monsoon rainfall over India. An opposite configuration of the mid-latitude circulation pattern tends to accompany below normal Baiu rains over Japan and above normal monsoon rains over India.

40 ref

009855   Khanna V K (Department of Geology, Govt. Autonomous Science College, Jabalpur-482 001) : Jabalpur earthquake of 17 October 2000. J Geol Soc India 2001, 57(1), 84.

^ssc2 ref

009854   Karanth R V;Sohoni P s;Mathew G;Khadkikar A S (Department of Geology, Faculty of Science, M.S. University of Baroda, Vadodara-390 002) : Geological observations of the 26 January 2001 Bhuj earthquake. J Geol Soc India 2001, 58(3), 193-202.

Entire Gujarat State in general and Kachchh region in particular experienced one of the most devastating earthquake in the Indian shield on 26th Janurary 2001. This earthquake has caused significant damage to life and property and is one of the most important seismic events that can serve as a modern analogue for studying ground deformation caused on account of large magnitude earthquake in the stratigraphic record. Mainly four different kinds of ground deformation have been observed in Kachchh : large scale ground fissuring, lateral spreads/faulting, rock falls and slumping and liquefaction and fluidization. Intense ground deformation is seen in the domain of Kachchh Mainland Fault (KMF). Most of the intense liquefaction and ground-rupture sites fall along the extent of KMF which indicates that a part of Kachchh Mainland Fault has been activated between Kunaria in the west to Adhoi in the east during this earthquake.

6 illus, 15 ref

009853   Joshi D D (NO, Geological Survey of India, Northeastern Region, Shillong) : Geoenvironmental problems of the glacial belt of Bhutan higher Himalaya and remedial measures: a case study of Raphstreng lake in Lunana area. J Geol Soc India 2001, 57(1), 65-76.

Lofty mountain ranges of Bhutan Higher Himalaya having altitude ± 7000m are covered with perennial snow and give rise to a number of valley glaciers all along their southern slopes. The area of study lies just at the foot of these mountain ranges and represents a glacial landscape strewn with lake, morainic ridges and glaciofluvial terraces. The rock types present in the area are granite gneisses belonging to Thimphu Group. The study encompasses the geomorphological and geoenvironmental aspects of the area. This mainly includes processes of formation of dangerous glacial lakes, which causes devastating flash floods on bursting. This glacial belt which forms the upper catchment of Sankosh (Pho Chu) river has had a history of flash floods caused by the bursting of glacial lakes. The latest devastating flash floods took place in 1994, which were caused by the bursting of glacial lake in the Lunana area. Another glacial lake is in a critical state since a sizeable part of its morainic dam was washed away due to the flash floods of 1994. The evolution of this glacial lake and its hydrological, bathymetric and safety aspects are discussed in detail.

10 illus, 10 ref

009852   Hart M B;Joshi A;Watkinson M P (Department of Geological Sciences, University of Plymouth, Drake Circus, Plymouth PL4 8AA, United Kingdom) : Mid-late cretaceous stratigraphy of the cauvery basin and the development of the eastern Indian ocean. J Geol Soc India 2001, 58(3), 217-29.

Planktonic foraminifera are widely used in Cretaceous stratigraphy and have a well-established zonation for low latitude regions. The most recently published version includes some of the proposals for the Cretaceous stage boundaries introduced at the meeting of the International Sub-Commission on Cretaceous Stratigraphy held in Brussels in 1995. This zonation is identified in the sediments of the Cauvery basin and correlated with the ODP boreholes on the Exmouth plateau and Western Australia. The maximum diversity of planktonic foraminifera in the Cauvery basin can be correlated with the highest temperatures in the Cretaceous and the Mesozoic sea-level maximum. Both of these appear to relate to enhanced rates of ocean crust production. The distribution of planktonic foraminifera in the developing eastern Indian Ocean can also be used in palaeogeographical reconstructions that confirm the predicted palaeotemperatures.

6 illus, 72 ref

009851   Golani P R;Bhattacharyya D;Sanyal S;Kirmani I R;Malhotra G;Bhattacharyya S;Grover A K;Narang J L (Geological Survey of India, , Western Region, 15-16, Jhalana Dungri, Jaipur-302 004) : Gold potential of epithermal breccia along the Deldar - Kui-Chitrasani fault in South Delhi fold belt, Southwest Rajasthan and Northern Gujarat. J Geol Soc India 2001, 57(2), 149-56.

Deldar-Kui-Chitrasani (DKC) fault is a brittle structure manifested by anastomosing system of fractures in the southwestern part of the South Delhi Fold Belt (SDFB). Based on the identification of cross-fibre and 'Jigsaw puzzle' type structures, presence of vugs lined with cryptocrystalline quartz, replacement of calcite by chalcedonic quartz and evidences of argillic alteration, the breccia along the fault is recognised by present workers as epithermal breccia. Lithogeochemical sampling of the breccia reveals that, besides moderate base metal signatures, gold values are consistently present in significant concentrations comparable to regional anomalies associated with epithermal gold deposits in the United States. In view of the high proportion of magmatic rocks in the southwestern part of the SDFB, the DKC fault zone is considered a favourable target for searching epithermal type of gold mineralisation.

4 illus, 1 table, 23 ref

009850   Gaur M L (Research Centre, Central Soil and Water Conservation Research & Training Institute, Gwalior Road, Datia-475 661) : Ground water recharge estimates of a small watershed. Indian J Soil Conserv 2001, 29(2), 126-32.

Ground water (GW) is a precious as oil pool and needs judicious exploitation for sustained hydro-ecological equilibrium of an area. This requires accurate estimates of prevailing GW recharge components using simpler procedures. In the present study attempt has been made to quantity GW budget of a 1381 ha watershed comprising predominant cultivable wastelands. Water table fluctuation method was applied along with GW parameters/norms prescribed by Central Ground Water Board for the local area. The net annual draft through 350 shallow dug-wells was predicted as 1.89 million cubic meters (MCM), while the net annual recharge came around 2.058 MCM leaving a GW balance of 0.1687 MCM. Maximum GW drafts (Gross value; 2.02 MCM) were experienced in non-monsoon period. The major fraction of annual recharge (Gross value; 1.91 MCM) was contributed from monsoon rainfall. The existing stage of GW development was found to be safe and satisfactory still having scope for its further enrichment.

3 illus, 3 tables, 10 ref

009849   Gaitan Vaz G;Vijaykumar P (NO, , East Coast Operations II, Marine Wing, Geological Survey of India, 41, Kirlampudi Layout, Visakhapatnam-530 017) : Occurrence of upper oligocene - lower miocene rocks in the upper continental slope, off the southern part of Cauvery basin. J Geol Soc India 2001, 57(2), 141-7.

Seabed survey off the southern part of Cauvery basin revealed the exposure of well indurated ferruginous fossiliferous limestone in the upper continental slope ESE off Nagapattinam. The presence of benthic foraminiferal fossil viz. Miogypsina sp. assigns Upper Oligocene - Lower Miocene age to the ferruginous limestone. The limestone exposure in the upper continental slope suggests the northeasterly offshore extension of the sub-basin viz., Ramnad - Palk Strait Depression.

6 illus, 1 table, 21 ref

009848   Gahalaut V K;Kalpna K (Natl Geophys Res Inst, , Uppal Rd, Hyderabad-500 007) : On the geodetic observations during 1965 to 1969 in the Koyna region, India. J Geodyn 2001, 31(5), 499-505.

Limited reports of repeat triangulation and levelling surveys carried out in the Koyna region by Survey of India, before and after the 1967 Koyna earthquake, are available. Analyse these observations of horizontal and vertical displacements to investigate whether analysis of these observations can provide additional constraints on the source parameters of the 1967 Koyna earthquake. Calculates surface displacements due to coseismic slip on the subsurface rupture of the 1967 Koyna earthquake and also due to the Koyna reservoir water load. Finds that the reported displacements are too large to be attributed to the coseismic displacements and/or to the displacements induced by the reservoir water load. Concludes that these observations contain large random and systematic errors.

14 ref

009847   Borgohain R;Khound D J;Bhuyan D;Phukan J (KDM Project, Department of Applied Geology, Dibrugarh University, Assam) : Petrographic study of the Therria-Lakadong unit of upper Assam basin. J Geol Soc India 2001, 57(2), 157-69.

Therria - Lakadong unit forms a part of the Upper Assam Basin explored by the Oil India Limited. Petrographic study on 47 subsurface samples drawn from 3548.5m to 4377m in five well sections has revealed that the sandstone type is dominantly wacke, minor arenite and calcareous sandstone with quartz content varying from 31.4 to 82.7%. The other constituents are feldspar, rock fragments, cement, matrix, mica, opaques, glauconite and fossils. The limestone comprises sparry calcite, micrite, bioclasts, peloids, quartz, opaques and glauconite. The heavy minerals recorded are zircon, rutile, titanite, epidote, garnet, hornblende, enstatite, hypersthene, augite and kyanite with traces of diopside, sillimanite, brookite and monazite. The heavy mineral assemblage suggests that the sediments were derived from igneous, metamorphic and sedimentary rocks. Based on IR and XRD studies, the clay minerals were identified as kaolinite, illite, montmorillonite and chlorite, which together with glauconite, suggest a nearshore depositional environment. Biosparite indicates high-energy conditions in the environment. Although some of the original porosity is lost at depth due to pressure effects, the sandstone in general has good porosity.

6 illus, 6 tables, 20 ref

009846   Banerjee P K;Vaz G G;Sengupta B J;Bagchi A (NO, , C-1, Greenwood, 315B, Upen Banerjee Rd, Calcutta-700 060) : Qualitative assessment of seismic risk along the Peninsular coast of India, south of 19 degrees N. J Geodyn 2001, 31(5), 481-98.

Presents illustrative evidence of some active faults which are recognisable on coastal land by displaced Pleistocene weathered cover, hot springs, leakages of native mercury and allochthonous geochemical anomalies of base metals, and offshore below the inner shelf by horst-shaped uplifted segments and intra-formational slump folds on and below the top shallow seismic (3.5 kHz) reflector. On the other hand, there are long stretches of the east coast at Vishakhapatnam and Manappad Point, which do not show active faults. Step-like marine terraces, which occur up to + 6 in above the low tide level (LTL). Preserve records of relative sea level fluctuations during the Holocene and the Last Interglacial. In such sectors, absence of tectonic disturbances during the last 100 ka is also corroborated by lateral continuity of shallow seismic reflectors below the inner shelf over many kilometers. Since authentic historical (200-1000 years B.P.) records of seismicity along the penisular coast are virtually unavailable. The likely recurrence interval between earthquakes in each sector cannot be gauged. Proposes a scale of seismic risk, based on geometry of the mappable faults and available seismic records of the last two centuries. These could be used in combination to rank the densely populated coastal tracts sector-wise.

66 ref

009845   Ballukraya P N (Department of Applied Geology, University of Madras, Guindy Campus, Chennai-600 025) : Hydrogeophysical investigations in Namagiripettai area, Namakkal district, Tamil Nadu. J Geol Soc India 2001, 58(3), 239-49.

Results of high-density vertical electrical soundings in an over-exploited area show that the borewell yields are not generally correlatable with any of the geoelectrical parameters. Many of the lineaments mapped from satellite imageries could be identified from geoelectrical profiles/section, but the same could not be done from spatial distribution maps of either hydrogeological or geoelectrical parameters. Two lineaments could be identified from the depth ot bedrock map, though wells along these lineaments do not necessarily have higher yields. It appears that most of the so-called lineaments mapped from satellite images/aerial photographs are in reality, not structures controlling groundwater occurrence and movement, at least in an over-exploited area, where the water-bearing zones are at considerable depths. However, the usefulness of both the techniques in identifying deep fractured rock zones is established from the results of the study. In view of the pronounced inhomogeneity present in hard rock area, it is clear that the soundings must be as close as possible to each other in order to get a clear picture of the sub-surface.

6 illus, 1 table, 22 ref

009844   Anbarasu K (Department of Geology, Delhi University, Delhi-110 007) : Acritarchs from mesoproterozoic Chitrakoot formation, semri group, Chitrakoot area, Central India. J Geol Soc India 2001, 57(2), 179-83.

Black and dark brown chert lenses of non-stromatolitic Glauconitic Limestone Member of Chitrakoot Formation belonging to Lower Vindhyan and exposed in the southern portion of the Sangrampur hill section, have yielded organically welll preserved acritarchs and filamentous microfossils in petrographic thin sections. Inventory of the acritarch Cymatiospheroides kullingii and unnamed form `A' contributes to the acritarch database of Vindhyan microbiota.

2 illus, 18 ref

009843   Agnihotri Y;Murti R (NO, Central Soil and Water Conservation Research and Training Institute, R, Chandigarh) : Relationships between onset of monsoon with sowing weeks and monthly/seasonal rainfall at Chandigarh. Indian J For 2001, 24(2), 146-9.

2 illus, 2 tables, 3 ref

008757   Yadav O P;Babu T B;Shrivastava P K;Pande A K; Gupta K R (Atomic Minerals Directorate for Exploration and Research, Department of Atomic Energy, Western Region, Jaipur-302 004) : Report of quaternary sedimentaiton and its significance in west Jahajpur basin, Bhilwara district, Rajasthan. J Geol Soc India 2001, 58(6), 539-42.

Quaternary sequences of mud/silt with carbonaceous matter and coaly layers, sandstone and conglomerate is found in the structural depressions near Jahajpur basin in Rajasthan. Uranium is also found in these sediments which may have been derived from the basement of Berach Granite and phyllites of Jahajpur Group.

^ssc2 illus, 1 table, 4 ref

008756   Viswanatha G;Anantha Murthy K S; Chandrashekarappa K N (Department of P.G. Studies and Research in Applied Geology, Kuvempu University, Sahyadri College Campus, Shimoga-577 203) : Landslide evaluation of Agumbe region of Western Ghats, Karnataka, India. Indian Mineralogist 2000, 34(2), 18-24.

Landslides are the most common geological hazards in the Western Ghat region Agumbe Ghat region forming a part of Western Ghats of Karnataka too has witnessed a landslide on 18th July 1999 at the fomous sunset viewpoint. The evaluation of geoenviron-mental conditions reveals factors such as steep slope (60°-65°), highly weathered and jointed/fractured schists/phyllites, presence of clay in the joints/fractured openings, continuous and heavy rainfall, modification of the natural slope by road cutting and ceased drainage system are respondible for the slope failure.

2 illus, 2 tables, 5 ref

008755   Virender Kumar (Geological Survey of India, , 15-16 Jhalana Dungri, Jaipur-302 004) : Geological set-up and mineral resources of Nagpur - Ganganagar basin, Rajasthan. Indian Miner 2001, 55(1-2), 1-30.

Sedimentary package of the Nagpur-Ganganagar basin commencing from the Late-Proterozoic Jodhpur, Group of rocks to the Quaternary sediments contains vast resources of building stones and materials, clays, limestone, dolomite, anhydrite, gypsum and gypsite, rock phosphate, natural hydrocarbons and lignite deposits. Possibility of the presence of native sulphur also can not be rule out in the Eocambrian evaporite sequence. Exploration and exploitation of these mineral resources are to be carried out for the development of the area.

2 illus, 3 tables, 57 ref

008754   Ugarkar A G;Suresha K J;Srikantappa C (Department of Geology, Karnataka University, Dharwad-580 003) : Fluid inclusions in the western auriferous zone of Gadag gold field, Karnataka. Indian Mineralogist 2000, 34(2), 91-9.

Gadag Gold Field hosts three gold ore bearing zones, namely Western, Central and Eastern auriferous zones distributed both in metavolcanic and metasedimentary suites. The Western auriferous zone which is hosted by metavolcanics occurs along the system of structurally controlled, intensely sheared zones which are parallel/subparallel to the regional schistosity. Mineralisation is gold-quartz-vein type, and is invariably associated with the hydrothermal wall rock alteration characterised by the ubiquitous presence of chlorite, muscovite, sericite, carbonate, quartz mylonites and iron sulphide disseminations and bands. Three types of fluid inclusion viz., H2O, CO2 and mixed H2O-CO2 inclusions have been recorded in gold-quartz veins in the western auriferous zone. Fluids are isolated to negative crystal in shape, varying in size from 8 to 14 um. Microthermometric measurements of these inclusions indicate that the auriferous hydrothermal fluids were of low salinity (2-6 wt% NaCl), dominated by H2O-CO2 (20-40 mole% CO2) with moderate densities (0.8-1.0 g/cc). Mineralization of gold occurred over a temperature range of 230°-260°C. During shear deformation, post dating the regional metamorphism, interaction of gold bearing H2-O - CO2 - NaCl fluids with the wall rocks at decreasing PT conditions (Shear zone vicinity) might have lead to fluid immiscibility and separate.

3 illus, 1 table, 24 ref

008753   Suvarna Kumari N;Rajagopalan Nair S;James E J (CWRDM Sub Centre, , Neyyattinkara) : Geomorphic developments of micro - watersheds of Chittar basin with respect to sinuosity index. J appl Hydrol 2001, 14(1), 13-17.

Morphometric analysis has been carried out to study the drainage pattern of the Chittar sub basin in Thiruvananyhapuram District of Kerala State in India. Chittar sub basin consists of five small watersheds viz Panachamoodu, Kudayal, Aruviyode, Trippalavur and Marayamuttam. The stream order ranges from second to third order. Shapes of the three basins are elongated, one oval and the other one is less elongated. From the analysis it was inferred that four watersheds are in the youthful stage and the other one is early matured.

6 illus, 1 table, 5 ref

008752   Srivastava P K;Bhattacharya A K (Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur-721 302) : Delineation of ground water potential zones in a hard rock terrain of Bargarh district, Orissa using IRS data. J Indian Soc Remote Sens 2000, 28(2-3), 129-40.

Various groundwater potential zones for the assessment of groundwater availability in a hard rock terrain have been delineated with the help of hydrogeological parameters using satellite IRS-1B-LISS-II digital data. Area selected for this study is a part of Bargarh district, Orissa, India covering an area of about 680 square km. Satellite data has been used to prepare geological-cum-lineaments, geomorphological, landuse and drainage maps. The various thematic maps have been integrated with the help of Geographic Information system to demarcate the poor to excellent groundwater potential zones. Weightage has been given to various groundwater controlling factors to the total groundwater potential in each segment of study area. Subsequently, several sites were selected and pumping tests carded out in the area. The results show that among others, lineaments as well as drainage density are the most important contributory factors in the groundwater potential of various geomorphic units in the area of investigation.

9 illus, 1 table, 13 ref

008751   Sreedharan K E;John S (Centre for Water Resources Development and Management, , Kunnamangalam P.O., Kozhikode-673 571) : Rainfall-runoff model for a river basin in Kerala. J appl Hydrol 2001, 14(1), 24-9.

Linear perturbation model (LPM) is applied to the Meenachil river basin of Kerala. Both non-parametric (unconstrained) and parametric (gamma function) forms of the model are applied. Ten years of daily rainfall and concurent riverflow data are utilized for the study. Eight years of data has been used for calibration of the model and the subsequent two years for verification purpose. Parameter optimisation is carried out by the method of ordinary least squares in the non-parametric case while in the gamma function form, Rosenrock's search technique has been made use of. Efficiencies of both non-parametric and parametric forms are compared. It is seen that even though there is unrealistic oscillations in the tail portion of the pulse response function in the non-parametric form, a better efficiency is observed compared to that of the gamma function form. Better efficiency can be obtained with more data for calibration and verification periods.

2 illus, 1 table, 11 ref

008750   Singh Y;Singh K D P (Atomic Minerals Directorate for Exploration & Research, , Begumpet, Hyderabad-500 016) : X-ray mineralogy and cerium-yttrium-niobium-tantalum geochemistry of granitic soil from Muskel-Kawadgaon area, Bastar craton, central India. Indian Miner 2001, 55(1-2), 47-54.

X-ray diffraction (XRD) and geochemical (Ce, Y, Nb and Ta) studies on granititc soils from Muskel-Kawadgaon area, Bastar craton, central India indicate the presence of ilmenite, monazite, zircon and rutile in decreasing order of abundance, besides common minerals. Assay values of panned concentrates (n-17) show isolated elevated concentration of cerium (av. 0.28%) and yttrium (av. 0.08%) with low values of nobium (av. 0.03%) and tantalum (av. 0.07%) in granitic soils. Ce/Y ratio of 3.5 in granitic soils is slightly more than the average granite (2.25 whereas Ta/Nb ratio of 2.3 ius anomalously high being about 13 times more than the average granite (0.157). High Ta/Nb ratio indicate that source granitic melt possibly had similar anomalously high Ta/Nb ratio.

2 illus, 2 tables, 27 ref

008749   Singh L N;Regar R L;Singh S L;Agrawal A K; Prasad R N (Geophysics Division, Geological Survey of India, , W.R. Jhalana Dungri, Jaipur-302 004) : Role of geophysics in designing the new spillway of morel dam, Sawai modhopur district, Rajasthan. Indian Miner 2001, 55(1-2), 77-84.

Presents the results of geophysical surveys employing Vertical Electrical Sounding (VES) and refraction seismic (Hammer source) techniques which were carried out at waste weir site of Morel dam, Sawai Madhopur district, Rajasthan to delineate bed-rock topography for designing the new spillway besides the present one to provide for higher discharge during the rainy season as observed in earlier unprecedented floods. The depths of bedrock inferred from electrical and seismic surveys are in good arrengement. The depth varies from 10 m to 25 m below ground level with P-wave velocity 3000 to 5600 m/s and resistivity 102 to 1320 ohm-m or more. The depth given by 6 earlier boreholes drilled in area of present geophysical investigation are in excellent agreement with those obtained by 6 test electrical and seismic sounding conducted at borehole locations. This lends additional credence to geophysical results obtained in the area. Three depressions indicated in bedrock appear to be due to palaeochannel. The analysis of geophysical data indicates that the new spillway may be constructed at about 250 m east of the present one.

6 illus, 1 table, 5 ref

008748   Singh B (Geological Survey of India, , ) : Geological set up of the eastern part of the Shyok ophiolite structural belt, Ladakh Himalaya. Indian Miner 2001, 55(1-2), 99-104.

Trans-Himalayan Shyok ophiolite structural belt occurs parallel to the Indus ophiolite belt of the central Ladakh. In the Shyok-Chushul section, it is thrust over by the Precambrian to Permian Pangong Group together with the Karakoram Tethyan post-Permian Lukung Formation and associated Cretaceous to Neogene Karakoram Granitoids. The rocks of the Shyok Group were represented by Middle Triassica (Anisian) to early Cretaceous Tsoltak and Middle to late Cretaceous (Aptian - Albian to Cenomanian) Chushul Formation. The ophiolite bodies are variously emplaced with the Tsoltak Formation.

1 illus, 2 tables, 16 ref

008747   Shukla P N;Bhandari N;Das A;Shukla A D;Ray J S (Physical Research Laboratory, , Ahmedabad-380 009) : High iridium concentration of alkalinerocks of Deccan and implications to K/T boundary. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(2), 103-10.

Reports an unusually high concentration of iridium in some alkali basalts and alkaline rocks of Deccan region having an age of about 65Ma, similar to the age of the Cretaceous-Tertiary Boundary. The alkali basalts of Anjar, in the western periphery of Deccan province, have iridium concentration as high as 178pg/g whereas the alkaline rocks and basalts associated with the Amba Dongar carbonatite complex have concentrations ranging between 8 and 80 pg/g. Some of these values are more than an order of magnitude higher than the concentration in the tholeiitic basalts of Deccan, indicating the significance of alkaline magmatism in the iridium inventory at the Cretaceous-Tertiary boundary. Despite higher concentration, their contribution to the global inventory of iridium in the Cretaceous-Tertiary boundary clays remains small. The concentration of iridium in fluroites from Amba Dongar was found to be <60> 30 pg/g indicating that iridium is not incorporated duing their formation in hydrothermal activity.

2 illus, 2 tables, 31 ref

008746   Shukla A D;Bhandari N;Kusumgar S;Shukla P N; Ghevariya Z G;Gopalan K;Balaram V (Physical Research Laboratory, , Navrangpura, Ahmedabad-380 009) : Geochemistry and magnetostratigraphy of deccan flows at Anjar, Kutch. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(2), 111-32.

Chemical analysis of nine Deccan flow basalts at Anjar, Kutch, western India, indicates that all, except the uppermost flow F-9, are alkaline. In their major and trace element composition, the alkali basalts resemble Ocean island basalts (OIB). Similarities of many diagnostic trace element ratios (e.g. Sm/Nd, Ba/Nb, Y/Nb and Zr/Nb) are similar to those found in the Reunion Island basalts. The uppermost basalt is tholeiitic and chemically resembles the least contaminated Deccan basalt (Ambenali type). The Anjar basalts have iridium concentration ranging between 2 and 178 pg/g. Some of these values are higher by about an order of magnitude compared to the Ir concentration in other basalts of the Deccan. A synthesis of chemical, palaeomagnetic and geochronologic data enables us to construct a chemical and magnetic stratigraphy for these flows. The three flows below the iridium enriched intertrappean bad (IT III) show normal magnetic polarity whereas all except one of the upper basalts show reversed magnetic polarity. The sequence seems to have started in polarity zones 31N and probably continued up to 28R or 27R. The results support the view that Deccan volcanism in Kutch occurred on a time span of a few million years.

11 illus, 7 tables, 73 ref

008745   Sharma M D (Department of Mathematics, Kurukshetra University, Kurukshetra-136 119) : Scattering of a spherical pulse from a small inhomogeneity: Dilatation and rotation. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(3), 205-13.

Perturbations in elastic constants and density distinguish a volume inhomogeneity from its homogeneous surroundings. The equation of motion for the first order scattering is studied in the perturbed medium. The scattered waves are generated by the interaction between the primary waves and the inhomogeneity. First order scattering theory is modified to include the source term generating the primary waves. The body force equivalent to the scattering source is presented in a convenient form involving the perturbations in wave velocities and gradient of density perturbation. A procedure is presented to study the scattering of a spherical pulse from a small inhomogeneity, in time domain. The size of inhomogeneity is assumed small as compared to its distance from source and receiver. No restrictions are placed on the positions of source, receiver and inhomogeneity. The dilatation and rotations are calculated for a pulse scattered from an arbitrary point in a spherical volume. The aggregate of the scattered phases from all the points of the inhomogeneity, reaching at a fixed receiver, gives the amount of scattering from the inhomogeneity. The interaction of both P and S waves with inhomogeneity are considered. Dilatation and rotations for scattering are obtained as integral expressions over the solid angle of inhomogeneity. These expressions are computed numerically, for hypothetical models.

5 illus, 27 ref

008744   Sengupta K (Petrology Division, Eastern Region, Geological Survey of India, , 15 Kyd Street, Calcutta-700 016) : Some observations on the micas and feldspars from the pollucite-bearing pegmatites and aplites of Belamu and Katanga areas, Purulia district, West Bengal. Indian Miner 2001, 55(1-2), 105-08.

^ssc2 tables, 9 ref

008743   Sarkar S;Bandyopadhyay M;Dikshit A K;Patra H P;Nath S K (Department of Geology and Geophysics, Indian Institute of Technology, Kharagpur-721 302) : Analysis of pump test data and design of radial collector well on damodar river bed near edilpur, Burdwan district, West Bengal (India). J appl Hydrol 2001, 14(1), 30-45.

Comprehensive study of the hydrogeological and hydrological properties of the aquifer around Edilpur, Kathgolaghat (lat 23°13' N, long, 89°49' 33" E), District Burdwan (W.B.) was carried out on Damodar river bed. Geological and geophysical investigations on the river bed established the presence of extensive sandy formations confirmed by trial boreholes. Long duration (72 hours) pump test was carried out at points selected for main and observation wells. The generated pumping data were processed and the aquifer parameters (storage coefficient and transmissivity) estimated. The characteristics of the aquifer were found to be favourable enough for subsequent design of a radial collector well for supply of the quantity of water (20 MLD) needed for the project. The design details of the radial collector well for a supply of 20 MLD are also presented.

6 illus, 3 tables, 12 ref

008742   Sarkar P;Bandyopadhyay K C;Singh B;Sarkar S (Geological Survey of India, Central Petrological Laboratory, , 15 A&B Kyd Street, Kolkata-700 016) : Rare-metal-bearing pegmatite bodies within the Chotanagpur gneissic complex and its geological environ in Purulia district, West Bengal. Indian Miner 2001, 55(1-2), 55-66.

Petrographic and geochemical studies reveal that while most of these pegmatite bodies were barren, some are fertile and can be grouped into two discrete types, viz. LCT and NYF types as proposed by Cerny (1991). Significantly, the two sets of megalineaments crossing the area seem to harbour one of these geochemical types each; while the fertile ones with strong affiliation to the LCT type i.e. enriched with rare metals like Li, Rb, Cs, Be, Ga, Sn, B, P, F and Nd<60>Ta components are associated with the ENE-WSW-trending megalineament, the others with NYF affinity i.e. enriched in Y, REE, SC, Ti, Zr, Be, Th, U, F and Nb<60>Ta components are associated with the E-W-trending one commonly known as the North Purullia Shear Zone. The rare metal (RM)-bearing pegmatites of the area show some degree of mineral zoning with the presence of pale pink or pale brown mica, pale green tourmaline, apatite, fluorite and pollucite (the ore of `Cs' metal). Chemical study of four sizeable rare-metal-bearing pegmatite bodies show high content of Cs-maximum up to 15.70% (mainly within the pollucite), Li - maximum up to 0.55<60> (mainly within the mica) and Rb-maximum up to 0.49%. Petrographic and X-ray studies confirm that these four rare pegnatic bodies contain appreciable amounts of pollucite.

5 illus, 4 tables, 17 ref

008741   Sanjeevi S;Barnsley M J (Centre for Geo-Science and Engineering, Anna University, Madras-25) : Spectral unmixing of compact airborne spectrographic imager (CASI) data for quantifying sub-pixel proportions of biophysical parameters in a coastal dune system. J Indian Soc Remote Sens 2000, 28(2-3), 187-204.

Identification and mapping of favourable (sandy), and unfavourable (scrub rich) habitats form the key to coastal conservation and management. In highly mixed floral environments, however, such an identification is difficult with low resolution multispectral imagery. In such cases, spectral unmixing is useful to resolve the "mixed pixel" effects. The Kenfig NNR (National Nature Reserve), South Wales, UK, bestowed with high biodiversity, is facing loss of successionally young slack habitats due to dune stabilisation and vegetation succession. To map such habitats, linear spectral unmixing of airborne. MSS (CASI-Compact Airborne Spectrographic Imager) data was performed using the Constrained Least Square (CLS) method, and the subpiex proportions of the spectral end members viz. sand, vegetation and shade/moisture were defined. Comparison of the estimated fractions with the grwoth forms of the dominant vegetation species Salix repens (Creeping willow) with classified digital aerial photographs shows a positive correlation, thus giving us confidence in the mixture modelling technique. Apart from aiding in conservation management, such a fuzzy classification of multi-date imagery helps to delineate sandy and vegetated areas for change detection and landscape/habitat succession studies.

8 illus, 3 tables, 22 ref

008740   Samanta S K (Department of Geological Sciences, Jadavpur University, Calcutta-700 032) : Development of micro-scale joints in volcanic rocks under thermal stress. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(3), 191-203.

Petrographic studies of samples of the Rajmahal basalt reveal a variety of microscopic joints within phenocrysts, which seem to have developed under the influence fo thermal stresses during cooling. The theoretical analysis shows that: thermal stresses develop in a system only under unsteady state of cooling, the stresses responsible for the development of joints are tensile in nature, and the magnitude of stresses increase with increasing rates of cooling. In order to understand the effects of cooling rate on the mode of jointing, analogue model experiments were performed by quenching melt films of organic, crystalline materials under varying cooling conditions. In experiments, non-branching linear joints developed at relatively lower rates of cooling by a process of sub-critical crack propagation. On the other hand, at higher rates of cooling the mechanism of crack propagation was essentially supercritical leading to the development of branching joints.

9 illus, 12 ref

008739   Ray J S;Pande K (Ottawa-Carleton Geoscience Centre, University of Ottawa, Ottawa (ON) K1N 5N5) : <. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(3), 185-90.

⁴⁰Ar-³⁹Ar analyses of one alkali pyroxenite whole rock and two phlogopite separates of calcite carbonatites from the Sung Valley carbonatite-alkaline complex, which is believed to be a part of the Rajmahal-Bengal-Sylhet (RBS) flood basalt province, yielded indistinguishable plateau ages of 108.8±2.0 Ma, 106.4±1.3 Ma and 107.5±1.4 Ma, respectively. The weighted mean of these ages, 107.2±0.8 Ma, is the time of emplacement of this complex. This inplies trat sung valley complex and probably other such complexes in the Assam-Meghalaya Plateau postdate the main flood basalt event (i.e., the eruption of tholeiites) in the RBS province by <126> 10 Ma.

5 illus, 1 table, 20 ref

008738   Ranjbar H;Roonwal G S;Ravindran K V;Babar S (Department of Mining Engineering, Shaheed-Bahonar University of Kerman, Iran, ) : Synergetic use of remote sensing and geophysical data for exploration of porphyry copper deposits, using GIS. J Indian Soc Remote Sens 2000, 28(2-3), 205-12.

Darrehzar porphyry copper deposit is situated in the Urumieh-Dokhtar magmatic assemblage of central Iran. The integration of multiple geodata sets has been carried out using geographic information system for mapping lithology or hydrothermally altered rocks and also in selecting the best discriminating data elements for exploration of porphyry copper deposits located in areas with similar geological setting and climatic conditions. Principal component analysis is found useful for reducing large data sets into a few principal components. The integration of various geophysical data with SPOT image data through GIS has shown that the hydrothermal alteration and lithology can be mapped with more efficiency.

6 illus, 1 table, 30 ref

008737   Randhir Singh;Simon B;Joshi P C (Atmospheric Sciences Division, Meteorology and Oceanography Group, Spa, ISRO, Ahmedabad-380 015) : Estimation of surface latent heat fluxes from IRS-P4/MSMR satellite data. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(3), 231-8.

The brightness temperatures of the Microwave sensor MSMR (Multichannel Scanning Microwave Radiometer) launched in May 1999 onboard Indian Oceansat-1 IRS-P4 are used to develop a direct retrieval method for latent heat flux by multivariate regression technique. The MSMR measures the microwave radiances at 8 channels at frequencies of 6.6, 10.7, 18 and 21 GHz at both vertical and horizontal polarizations. It is found that the surface LHF (Latent Heat Dlux) is sensitive to all the channels. Coefficients were derived using the National Centre for Environmental Prediction (NCEP) reanalysis data of three months: July, September, November of 1999. The NCEP daily analyzed latent heat fluxes ad brightness temperature observed by MSMR were used to derive the coefficients. Validity of the derived coefficients was checked with in situ observations over the Indian Ocean and with NCEP analyzed LHF for global points. The LHF derived directly from the MSMR brightness temperature (Tb) yielded an accuracy of 35 watt/m². LHFa was also computed by applying bulk formula using the geophysical parameters extracted from MSMR. In this case the errors were higher apparently due to the errors involved in derivation of the geophysical parameters.

3 illus, 12 ref

008736   Randhir Singh N;Singh N S;Garg J K;Murthy T V R (Manipur Remote Sensing Applications Centre, , Imphal) : Loktak notified wetland ecosystem and its catchment. J Indian Soc Remote Sens 2000, 28(2-3), 159-69.

Conservation of wetland is considered paramount in view of its ecological significance. The availability of reliable and up-to-date data on seasonal water spread, tropic state of wetland and bio-physical parameters besides the landuse/cover of the catchment area is a prerequisite for 'wise use' of any wetland ecosystem. Study is carried out to identify the above parameters of Loktak notified wetland through visual interpretation of IRS IA/IB LISS II FCC of 1990 and 1994/95. It indicates that the water spread of the lake is showing a declining trend and an increasing trend for aquatic vegetation. In 1990 post-monsoon data water spread was 15441 ha which become 11166 ha in October 1994. The extent of water spread further decreases by pre-monsoon season and was found to be 7875 ha in the IRS LISS II data of March 1995. Like-wise area under aquatic vegetation and associated marshy/swamps was 10499 ha in October 1990 and 13506 ha in October 1994. Catchment of Loktak lake (104872 ha) is highly degraded and forest covers only 7205 ha area. Agriculture in the main level use (35576 ha) in the catchment and substantial area is also under land with or without scrub. Thus, there is a need to rehabilitate the catchment by way of planting trees for reducing silt load in the Loklak lake and ensuring its 'wise use'.

5 illus, 2 tables, 3 ref

008735   Rajdhan Singh N;Vajrappa H C (Department of Geology, Bangalore University, Bangalore-560 056) : Principal component analysis of hydrochemical data of Suvarnamukhi sub-basin of Arkavathi river, Bangalore district, Karnataka. J appl Hydrol 2001, 14(1), 8-12.

Principal Component Analysis (PCA) technique has been applied to major chemical constitutents of 95 bore well water samples from Suvarnamukhi Sub-basin for a systematic interpretation of hydrochemical data. PCA technique identified three dominant components, namely, TDS, carbonate and bicarbonate, which account for 74.82% of the major ion variations observed in the sub-basin.

3 tables, 10 ref

008734   Parameswaran K (Space Physics Laboratory, Vikram Sarabhai Space Centre, , Trivandrum-695 022) : Influence of micrometerorological features on coastal boundary layer aerosol characteristics at the tropical station, Trivandrum. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(3), 247-65.

The aerosol mixing height generally lies in the range 150 to 400 m showing a strong dependence on the vertical eddy mixing processes in atmospgeric boundary layer (ABL). Above this altitude, the number density decreases almost exponentially with increase in altitude with a scale height of 0.5-1.5 km. The aerosol mixing height is closely associated with the height of the Thermal Internal Boundary Layer (TIBL). Sea-spray aerosols generated as a result of the interaction of surface wind with sea surface forms an important component of mixing region aerosols at this location. This component shows a non-linear dependence on wind speed. On an average, depending on the season, the mixing region contributes about 10-30% of the columar aerosol optical depth (AOD) at 0.5μm wavelength. A long term increasing trend (<126> 2.8% per year) is observed in mixing region AOD from 1989 to 1997. A study on the development of the aerosols in the nocturnal mixing region shows that the convectively driven daytime altitude structure continues to persist for about 4-5 hrs. after the sunset and thereafter the altitude structure is governed by vertical structure of horizontal wind. Stratified aerosol layers associated with stratified turbulence is very common during the late night hours.

17 illus, 37 ref

008733   Pandey Y;Dharmaraju R;Chauhan P K S (NO, Central Building Research Institute, Roorkee-247 667) : Estimation fo source parameters of Chamoli earthquake, India. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(2), 171-7.

The devastating earthquake (mb = 6.6) at Chamoli, Garhwal Himalaya, which occurred in the morning hours on 29th March 1999, was recorded on Delhi Strong Motion Accelerograph (DSMA) Network operated by the Central Building Research Institute, Roorkee. The source parameters of this event calculated from the Strong Motion Data are presented. The seismic moment for this event has been found to be of the order of 10²⁵ dyne c. and the moment magnitude has been calculated in the range of 6.53-6.69 at different station. The stress drop and source radius for the earthquake are also calculated.

2 illus, 2 tables, 14 ref

008732   Nepal Singh;Sharma B K;Bohra P C (NO, Central Arid Zone Research Institute, Jodhpur-342 003) : Impact assessment of industrial effluent of arid soils by using satellite imageries. J Indian Soc Remote Sens 2000, 28(2-3), 79-92.

Visual interpretation of IRS-LISS-II (1:50,000 Scale) FCC, band 2,3 and 4 was carried out for the Industrial effluence assessment on soils (21900 ha) along the Bandi river course in Pali district of arid Rajasthan. Very severe (4378 ha), severe (3427 ha), moderate (5856 ha) and slight (1388 ha) categories of anthropogenic salt affected soils with the varied image characteristics in conjunction with ground truth have been identified and delineated from satellite imagery. The morphological and physico-chemical characteristics revealed that very severe category soil has thick salt crust dominantly in light gray color at surface, manifestation of strong sub-angular to angular blocky structure, extra-ordinary hardness, high ECe, SAR and ESP but low pHs. Severe category soils have light brownish gray colour at surface, manifestaion of strong angular to culumnar structure, high Ece, pHs, SAR and ESP but slightly lower than very severe category, Moderate category soils have light brownish gay colour at surface, moderate to strong manifestation of prismatic structure, low ECe but high pHs, moderate to high SAR and ESP. Slight category soils have pale brown colour and hard crust at surface, moderate hardness with the tendency to form weak prismatic structure in subsoil..

2 illus, 4 tables, 21 ref

008731   Murugan C;Ratna Reddy N;Chandrasekaran S; Viswanathan G;krishnan S;Azam A M (Atomic Minerals Directorate for Exploration and Research/DAE, , Trivandrum) : Occurrence of peat in the beach placer sands of Kootumangalam - Vettumadai area, Kanyakumari district, Tamil Nadu. Indian Mineralogist 2000, 34(2), 71-6.

Exploration of beach sands along the Kootumangalam-Vettumadai coastal tract reveals the existence of a peat horizon associated with the ilmenite-rich heavy minral accumulations. The peat horizon occurs within 50 m - 100 m from the High Tide Line, below the Water Table at a depth of 1 - 4.5 from the surface. The peat occurrences are lensoidal and occupy about ten per cent of the 35 hectares explored covering a beach length of 2.5 Km. The longer dimensions of the four lenses delineated parallel the present day East-West trending shoreline, the longest of them measuring 300 m X 100 m X 1.5 m. The peat bodies have thickness ranging from a few cm to 2.0 m. They attain maximum thickness at their southern margins. The peat is dark brown, hard, compact, and soils the fingers, and contains 10% to 17% moisture and 50% volatile matter. The placer mineral sand in which the peat is embedded contain rich concentration (18%-23%) of economically important heavy minerals principally ilmenite, rutile, zircon, monazite, sillimanite and garnet. The pear horizon itself is inter-layered with the heavy minerals indicating coeval deposition of plant debris and placer mineral sands, perhaps in a marshy environment. The placer mineral sand of Kootumangalam and Vettumadai area, occurring near the existing mineral separation plant at Manavalakurichi, are of exploitable grade.

1 illus, 3 table, 4 ref

008730   Muralidhar M;Raju K R K;Prasadaraju K S V; Rajendraprasad J (Department of Geology, Osmania University, Hyderabad) : Remote sensing applications for the evaluation of water resources in a rainfed area, Warangal district, Andhra Pradesh. Indian Mineralogist 2000, 34(2), 33-40.

Cherial area of Warangal district falls under tropical and semi-arid climatic regions. The area receives most of its rainfall from SW monsoon wherein agriculture is the principal activity. More than 80% of the cropped area represents rainfed agriculture. Groundwater in the area occurring under unconfined and semiconfined conditions is extracted through large diameter open wells and bore wells. Integrated and environmentally sustainable development strategies have become inevitable for micro-level planning. The usefulness of remotely sensed data from earth resource satellites for water resource management on a watershed approach is discussed for a wateshed in Cherial area of Warangal district of A.P. Remote sensing data have been used to differentiate different hydrogeomorphological units and to delineate the major trends of linearments. The moderately weathered pediplains present in the study area are the most potential zones for groundwater targeting. Occurrence of lineaments in such zones is also a favourable indicator of ground water resources.

5 illus, 1 table, 3 ref

008729   Mukhopadhyay D K (Department of Earth Sciences, University of Roorkee, Roorkee-247 667) : Extreme heterogeneity in Sr isotope systematic in the Himalayan leucogranites: a possible mechanism of partial melting based on thermal modeling. Proc Indian Acad Sci-Earth Planet Sci 2001, 110(2), 161-9.

The small leucogranite plutons occurring in linear belts in the Higher Himalayas have formed due to post-collision partial melting within the Himalayan crust. Several studies have documented that the Sr isotopic ratios in the granite bodies show chaotic variation and meaningful Rb-Sr isochron ages are difficult, if not impossible, to obtain. In tectonically overthickened crust, the depth-temperature profile (geotherm) remains strongly transient for the first tens of millions of years. It is proposed here that the intersecting relations between the transient geotherms and activity-dependent solidus/melting curves may generate small pods of magma at different depths and at different times. Each of these pods will have its unique Sr isotopic ratios. Coalescence of these small pods of magma without any effective homogenization due to deformation-induced fast segregation, ascent and emplacement may lead to pluton-wide extreme heterogeneity in Sr isotopic ratiosxm.

6 illus, 1 table, 37 ref