000408   Singh A D (Marine Geology and Geophysics Dep, Cochin University of Science and Technology, Kochi-682 016) : Millennial-scale rapid fluctuations in the Arabian sea monsoon and oxygen minimum zone (OMZ) during the late quaternary. J Geol Soc India 2002, 60(2), 228-9.

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000407   Sikka D B;Nehru C E (NO, Cabinet-Conseil en Geologie Miniere Sikka ENR, 2108, 3463 Rue Ste, Famille, Montreal, Canada, H2X 2K7) : Malanjkhand copper deposit, India: is it not a porphyry type?. J Geol Soc India 2002, 59(4), 339-62.

Classification of the Malanjkhand as a porphyry type copper deposit is still being debated by some, despite the documentation of all the classic characteristics of the porphyry type deposit. A careful analyses and review of the available data, from many papers, unpublished theses and work on Malanjkhand, clearly documents it as a porphyry type copper deposit. Some of the salient factors in arriving at this conclusion are: low grade ore coupled with large tonnage, regional geologic and tectonic setting: Proterozoic host rocks of the malanjkhand deposit belong to a subduction zone calc-alkaline volcanic arc category, presence of stockwork type control, the genesis of mineralized quartz spatially related to the mineralized zone, zonation of the alteration products in the deposit, diverse ore mineral associations, and sulphur isotope data that are within the range of values expected for porphyry copper deposits.

9 illus, 2 table, 114 ref

000406   Siddiqui G;Ahmed M (Centre of Excellence in Marine Biology University of Karachi, , Karachi-75270) : Oyster species of the sub tropical coast of Pakistan (northern Arabian Sea). Indian J Mar Sci 2002, 31(2), 108-18.

Nine species of oysters belonging to three genera (Crassostrea, Saccostrea and Ostrea) were identified on the basis of their conchological and malacological features. These included Crassostrea gryphoides, C. madrasensis, C. belcheri, C. glomerata, Saccostrea cucullata, S echinata, Ostrea nomades, O. folium and O. cristagalli. Two species Ostrea nomades and O. cristagalli which are being reported for the first time from Pakistan. Crassostrea gryphoides and C. rivularis from Hub River Delta were earlier treated as separate species have been assigned to a single species C. gryphoides. Crassostrea gryphoides and C. madrasensis, which occur in the same habitat and show marked similarity in their external shell morphology, but differ in the colouration of their adductor muscle scar, are treated here as separate

5 illus, 1 table, 58 ref

000405   Shivanna S;Srivastava J K;Nambiar A R (NO, Geological Survey of India, Bangalore-560 078) : Kimberlite occurrence in Raichur area, Karnataka. J Geol Soc India 2002, 59(3), 269-71.

A large kimberlite body has been located for the first time in the Raichur District of Karnataka near Undraldoddi village. This is significant in view of ancient records of diamond recovery from Raichur, but primary source could not be identified so far in the area. The pipe is being investigated for the possible persence of diamonds.

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000404   Shastry A;Srivastava R K;Chandra R;Jenner G A (Geology Dep, Banaras Hindu University, Varanasi-221 005) : Geochemical characteristics and genesis of oceanic plagiogranites associated with south Andaman ophiolite suite, India: a late stage silicate liquid immiscible product. J Geol Soc India 2002, 59(3), 233-41.

Plagiogranite is leucocratic low-K member of the Andaman Ophiolite Suite (AOS) that occurs as bands (dykes?) of irregular shapes and sizes, particularly in the cumulate sequence of the suite. It is medium-to coarse-grained and commonly shows hypidiomorphic granular texture. At places granophyric texture (intergrowth between fildspar and quartz) is also seen. The main mineral constituents are plagioclase (mainly albite), quartz and minor mafic minerals. Mineralogically and chemically these rocks are classified as low-K dacite (trondhjemite/tonalite type). Low Rb concentrations (<60>5) and low Rb/Sr ratios (<60>0.015), observed in studied plagiogranites and associated Fe-Ti enriched rock, are characteristic of oceanic derivatives. All elements, plotted on the primordial mantle normalized multi-element spidergrams show enriched patterns. Variations in the concentrations of Nb, Sr, and Y are limited but other elements show wide variations. Strong negative anomalies for Nb are also observed. These rocks show characters analogous to those orogenic granites, emplaced in volcanic are settings. On the basis of observed petrological and geochemical are the integral part of AOS having crystallized from late stage immiscible silicate liquid.

7 illus, 2 tables, 30 ref

000403   Sengupta S (Geology Dep, Presidency College, 86/1 College Street, Kolkata-700 073) : Test shape of Nummulites cf. fichteli michelloti form a (:foraminiferida) from the early oligocene deposit of south western Kutch, India. J Geol Soc India 2002, 60(2), 223-4.

Study of the early Oligocene Basal Member of Maniyara Fort Formation (Biswas and Raju, 1973) between Khari (23" 28' N, 68" 41' E) and Bermoti (28" 28' N, 68" 6, E) in SW Kutch (Sengupta, 2000) shows conspicuous variation of test shape in Nummulites cf. fichteli Michelloti Form A though the sympatrically occurring A Forms of N. fichteli-clipeus group hava a more or less conservative lenticular test shape. Explores the significance of the above observation.

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000402   Seetharamaiah J;Bhagavan K V S;Nageswara Rao K (Delta Studies Institute, Andhra University, Sivajipalem, Visakhapatnam-530 017) : Recent morphological changes in the Penner estuary, east coast of India. J Geol Soc India 2002, 60(5), 563-5.

Study of sequential toposheets coupled with recent field observations revealed that Penner river has progressively shifted its mouth towards north during the past 80 years. This may partly be due to neotectonic activity and partly due to the development of new features at the estuary mouth. The newly formed distributary is likely to be widened further in the near future and possibly affect the coastal villages adjacent to its course.

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000401   Sashidharan K S;Mohanty A K;Gupta A (NO, Geological Survey of India, Seminar Hills, Nagpur-440 006) : Diamond incidence in Wairagarh area, Garhchiroli district, Maharashtra. J Geol Soc India 2002, 59(3), 265-8.

Incidence of diamond is reported from the highly deformed polymictic conglomerates of suspected Early Proterozoic age from Wairagarh area, Garhchiroli District, Maharashtra. The gem quality diamond recovered during the ongoing search for kimberlitelamproite rocks in western Bastar craton is an octahedral crystal with a light greenish tint and weighs 0.029g (0.15 carat). Reports of diamond mining in Wairagarh date back to as early as 15th century (Ball, 1884; Satyanarayana, 2000). Mining activity continued till 19th century (Streeter, 1882). These records provide information about richness of the mines and quality of the diamonds won. Despite intensive search by local people, there are no records of diamond recovery for over a century. The present find is first of its kind during the modern times and as opened up new vistas of diamond search in similar geological milieu in the western part of Bastar craton.

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000400   Sankaran A V (NO, , 10, P and T Colony, 1 Cross, II Block, R.T. Nagar, Bangalore-560 032) : Recent concepts about heat source from the earth's core. Curr Sci 2002, 83(8), 932-4.

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000399   Sahu K C (NO, , F-302, Powai Park, L-I Plot, Hiranandani Gardens, Powai, Mumbai-400 076) : Arsenic poisoning in the Gangetic delta: an anthropogenic model. Curr Sci 2002, 83(1), 21-2.

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000398   Reddy I V;Reddy M S;Satyanarayana G;Kalluraya V K K (NO, Geological Survey of India, Hyderabad) : New find of conglomerate horizons in southern part of Cuddapah basic and its stratigraphic significance. J Geol Soc India 2002, 59(3), 213-17.

New finds of oligomictic conglomerate at the base of Gulcheru Quartzite near Venganamala and at the base of Nagari Quartzite at Gadikota are reported. It is proposed that the Nagari Quartzite and Pullampet Formation are unconformably overlain by Bairenkonda Quartzite and Combum Formation, thereby necessitating a stratigraphic revision of the Nallamalai Group.

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000397   Raza M;Casshyap S M;Khan A (Geology Dep, Aligarh Muslim University, Aligarh-202 002) : Geochemistry of mesoproterozoic lower vindhyan shales from Chittaurgarh, Southeastern Rajasthan and its bearing on source rock composition, palaeoweathering conditions and tectono-sedimentary environments. J Geol Soc India 2002, 60(5), 505-18.

The Lower Vindhyan shales are characterized by high SiO₂, low CaO and MgO, very low Na₂O and very high K₂O/Na₂O ratio relative to average Proterozoic shales. All the shale units are severely depleted in Ca, Na and Sr and slightly enriched in some trace elements such as Co and Nb, relative to the early proterozoic upper continental crust. It appears that the high field strength and transition elements remained immobile throughout the sedimentary processes and represent the source rock composition. Geochemically, the individual shale units do not show any significant variation with age, excepting the Khardeola Shale that is relatively more enriched in ferromagnesian and large ion lithophile elements. Geochemical data suggest that sediments of Lower Vindhyan shales had their source in stable continental areas and deposited in intracratonic basin away from active plate boundaries. The immobile trace element data suggest that the source material of these shales have been derived from felsic and mafic components of Banded Gneissic Complex occurring to the west of the Great Boundary Fault in the proportion of about 4:1. Severe but non-steady-state weathering conditions in the source region having humid, and tropical climate appear to have prevailed throughout the sedimentation of Lower Vindhyan sequence. The sequence of events suggests passive type rifting environment during the Vindhyan Basin formation.

11 illus, 1 table, 59 ref

000396   Ravikant V;Guha D (G&IG Div, Geological Survey of India, Kolkata-700 016) : Ultrapotassic post-collisional dyke from the Ladakh batholith, northwest Himalaya. J Geol Soc India 2002, 59(5), 473-76.

Reports petrographic and bulk geochemical characters of an ultrapotassic dyke from the Ladakh batholith, NW Himalaya, for the first time, and attempt to compare it with similar dykes from SW Tibet which are typical of post-collisional magmatism. Post-collisional shoshonitic and ultrapotassic dykes have been reported from north Karakoram (Pognante, 1990) and potassic and ultrapotassic lavas from SW Tibet by Miller et al. (1999) linked to large scale tectonic reactivation involving the lithospheric mantle during the continued India-Eurasia collision since <126>50 Ma.

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000395   Ravi Shanker;Nag S;Shome S (NO, Geological Survey of India, Kolkata) : Incidence of gold in subgreenschist to greenschist facies metabasalt Bhowali, Nainital district, Uttar Pradesh. J Geol Soc India 2002, 59(4), 379-83.

Mesoproterozoic metavolcano-sedimentary sequence in and around Bhowali-Khairna area, Uttaranchal, constitute mostly metabasalts with quartzites, phyllites and variegated slates, referable to Bhimtal Formation. Study was centred on metabasalts and the rocks occurring in close spatial association with them. Detailed petro-mineralogical and SEM-EDS studies have revealed the presence of gold which reports there for the first time. Of the two types of metabasalts viz., massive, crudely foliated type and foliated type, both showing mineralogical assemblages of subgreenschist facies and greenschist facies respectively, gold is commonly found in the foliated type and rarely in the massive type. Presence of gold as tiny grains in disseminated fashion suggest that widespread hydrothermal activity caused precipitation of gold after the rocks had witnessed peak metamorphism.

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000394   Raval U (NO, National Geophysical Research Institute, Hyderabad-500 007) : Is there a major geodynamic node near Pondicherry, the site of 25th september, 2001 earthquake?. J Geol Soc India 2002, 60(2), 217-21.

Geophysical, seismic, tectonic and geodynamic evidences suggest that a tectonic node (or junction), more prominent than hitherto realized, may exist near Pondicherry.

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000393   Rao M S;Gopalakrishnan R;Dodhavari K S; Fareeduddin (PPOD Div, AMSE Wing, Geological Survey of India, Bangalore-560 070) : Three new candidate rock standards: granite dunite and anorthosite from Geological Survey of India, Bangalore. J Geol Soc India 2002, 59(3), 273-5.

Geological Survey of India, Bangalore has taken up the preparation of three International Rock Standards/Geostandards of granite from Chamundi Hills, Mysore (designated as GSI-CG-1), a serpentinised dunite from Dodkanya dunite/magnesite mines, Mysore District (designated as GSI-DD-1) and an anorthosite from the Sittampundi Anorthosite Complex, Salem District, Tamil Nadu (designated as GSI-SA-1). Details of te three rock-standards are provided for participative collaboration of interested geochemical laboratories.

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000392   Rao A T;Srinivasa Rao K;Vijayakumar V (Geology Dep, Andhra University, Visakhapatnam-530 003) : Basic volcanism along K- boundary from Rajahmundry east coast of India. J Geol Soc India 2002, 60(5), 583-6.

Basalts near Kateru, north of Rajahmundry in the East Godavari district and near Pangidi in the West Godavari district of Andhra Pradesh along the East Coast of India are of particular interest to investigators on account of their separation from the well known West Coast Deccan Basalts, localised around Bombay. The basalts around Rajahmundry are tholeiitic with equigranular, subophitic to ophitic textures. The principal constituents are plagioclase (An_55-56) and brownish nonpleochroic augite. The REE patterns of Rajahmundryb basalts have a marked increased enrichment in LREE due to crustal contamination. The K-Ar age of Kateru basalts is 75.1±4.9 Ma. The reported biochronostratigraphy of microfauna in the sediments closely associated in time and space with basalt flows in the Krishna-Godavari basin, east of Rajahmundry indicate that the age of basic volcanism is around 67 Ma. The lower limit of 70 Ma for the Kateru basalts supports that these basalts have evolved along with West Coast Deccan Basalts (69-65 Ma), where, the intensity of basic magmatism is more. The geological setting of Rajahmundry basalts with coastal sedimentary rocks indicate that the basic magmatism and sedimentation had taken place during the Cretaceous-Tertiary boundary.

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000391   Rao A D (Centre for Atmospheric Sciences, Indian Institute of Technology Delhi, Hauz Khas, New Delhi-110 016) : Variability of wind stress curl over the Indian Ocean during years 1970-1995. Indian J Mar Sci 2002, 31(2), 87-92.

Climatological and interannual variability aspects for monthly mean pseudo-stress curl over the Indian Ocean for the period 1970-1995 are explored. A harmonic analysis of the curl fields finds most of the variance of the northern basins dominated by semi-annual variability. In particular the coastal areas of Somalia and south/southwestern India have large contributions from this harmonic. In the southern basin, interannual harmonics are the primary ones of curl variance. Biennial oscillatory behaviour is only sporadically evident in various harmonics between 20 and 30 months, and was absent north of 10°S. An EOF analysis confirms that the summer monsoon is the dominant feature compared to the winter-monsoon. The mean positive curl in the eastern Arabian Sea indicated positive Ekman velocities (upwards) enhancing coastal upwelling in this region. More exceptional and not previously noted factor is an opposite and somewhat dramatic reduction of curl magnitude since 1988/89. The rate of decline is much larger than the (positive) trend in the early 1980's and was most notable in the early part of the summer monsoon. It is also evident in the winter monsoon periods, but not so for other months of the year. Additional evidence supports this change in variability pattern.

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000390   Ramiengar A S (NO, , C/o G.E. Spokes, C-13, Industrial Estate, Tumkur-527 103) : Carbonatite bodies of Dhanota-Dhancholi area in Mahendragarh district, Haryana. J Geol Soc India 2002, 60(5), 587-8.

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000389   Ramanathan V;Crutzen P J;Mitra A P;Sikka D (Scripps Institution of Oceanography, University of California, San Diedo, La Jolla, CA 92037, USA) : Indian ocean experiment and the asian brown cloud. Curr Sci 2002, 83(8), 947-55.

The Indian Ocean Experiment (INDOEX) was sponsored by research agencies within Europe, India and USA, and concerned with the haze over south Asia and the adjacent Indian Ocean. UNEP had commissioned a panel in 2001 to provide an early assessment of the societal implications of INDOEX findings. The long duration of the haze, its black carbon content, the large perturbation to the radiative energy budget of the region and its simulated impact on the rainfall distribution would have significant implications on the water budget, agriculture and health. The link between anthropogenic aerosols and reduction of monsoonal rainfall in south Asia has been made by over fifteen model studies preceding the UNEP report.

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000388   Ramakrishna T L (NO, , Flat No 228, I Block, Ushas Apartments, 4th T Block, Jayanagar, Bangalore-560 011) : Pictorial, colour coded geological and mineral map of Karnataka. J Geol Soc India 2002, 60(2), 199-202.

Geological and mieral maps in India are prepared using 1:63,360 or 1:50,000 or 1:25,000 scale topographic maps prepared by the Survey of India as base. hese are later compiled into smaller scales like 1:250,000 or 1:500,000 or 1:1,000,000 (commonly referred to as quarter million, half million or one million maps respectively) or larger scales depending on the need. These various scales represent the ratio of ground distances to those on the maps. The scale to be adopted depends upon the coverage or depth of details required. Geological maps show the spatial distribution of the various rock formations, their characteristics, as also the associated mineral occurrences or deposits on the respective topographic maps or topo sheets using standards colours and character symbols, as indicated in the legends accompanying these maps. Such maps while serving the prodessional geological needs represent just a flash of colours to the common man or a student. Of late there has been a lack of interest and appreciation of the wonderful branch of science, geology, among the upwardly mobile youth. Only a few take up geology for their graduate or post graduate studies and still less choose it for a career.

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000387   Ram Mohan M;Prasad P S R (NO, National Geophysical Research Institute, Hyderbad 500 007) : FTIR investigation on the fluid inclusions in quartz veins of the Penakacherla Schist Belt. Curr Sci 2002, 83(6), 755-60.

Penakacherla Schist Belt is a apart of the eastern Dharwar craton lying along the Ramagiri-Hungund arc. Fluids entrapped in quartz veins of two mafic volcanic rocks of this area are characterized by FTIR spectroscopy in the wave number region 2000-8000 cm^-1. The quartz-carbonate vein from the central part of the schist belt contains HO₂O, CO₂ and aliphatic hydrocarbon incusions, with bicarbonate in the form of nahcolite (NaHCO₃) coexisting with quartz, whereas, that from the nearly Bhadrampalli mine area is depleted in CO₂ and hydrocarbons, and enriched in H₂O inclusions. Distinctly clear signatures of silanol (Si-OH) group and the coexistence of calcite with quartz have also been observed in the latter quartz. These observations inidcate that re-cry-stallization of quartz in these two similar rocks occurred in vastly different hydrothermal environments.

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000386   Rajinder Singh;Bhat G M (PG Dep Geology, University of Jammu, Jammu-180 006) : Depositional settings of early carboniferous siliciclastic - carbonate succssion (syringothyris limestone) of Kashmir himalaya. J Geol Soc India 2002, 59(5), 431-45.

Early Carboniferous sequence of Kashmir represents a mixed siliciclastic - carbonate strata, where the lower part is dominated by carbonates and the upper part is rich in siliciclastic rocks. Siliciclastic sediments are mainly arenite, siltstone and claystone. Coarse grain size and bimodality of arenites suggest a high energy environment in the onshore region. Lithofacies and microfacies analyses of the carbonates reveal that they are deposited as turbidite either in the deeper part of the shelf or in the distal part of shelf/slope. Some of the carbonate facies, reflecting shallower microfacies, is deposited on the platform in subtidal and intertidal (pertidal) zone. The increase of siliciclastic material in the depositional basin indicates progradational phase of sedimentation which in turn suggests the lowering of sea level. These deposits represent peritidal (intertidal to subtidal) lithofacies. In fact, there has been retrogradational and progradational phases of sedimentation in the Tethyan basin of Kashmir, but the frequency of siliciclastics increases from middle to top of the Syringothyris Limestone. This feature suggests the overall shallowing of the basin, but intermittent deposition of carbonates reveals the periodic transgression or subsidence of the depositional basin.

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000385   Rajesekhara Reddy D;Malathi V (Geology Dep, Andhra University, Visakhapatnam-530 003) : Occurrence of kyanite in the nearshore sediments of north coastal Andhra Pradesh and its implication. J Geol Soc India 2002, 60(3), 329-31.

The heavy mineral assemblage in the nearshore sediments of north coastal Andhra Pradesh includes ilmenite, garnet, sillimanite, monazite, zircon, pyroxenes etc., and is derived from Eastern Ghat Group comprising dominantly khondalites and charnockites. The assemblage also consists of minor to accessory amounts of kyanite that has not been reported so far from the Eastern Ghat Group. Kyanite bearing rocks are reported from the Archaean schists of the Khammam District of Andhra Pradesh along the Godavari drainage basin. The evidences available so far suggest that the rocks from Godavati drainage basin are the sources for kyanite. However, further work is needed to confirm whether these rocks in the Godavari drainage basin or hitherto unreported kyanite bearing rocks in the other drainage basins constitute the provenance.

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000384   Rajendran K;Rajendran C P;Thakkar M;Gartia R K (NO, Centre for Earth Science Studies, Akkulam, Thiruvananthapuram-695 031) : Sand blows from the 2001 Bhuj earthquake reveals clues on past seismicity. Curr Sci 2002, 83(5), 603-10.

The 2001 Bhuj earthquake brought to focus several new issues on the seismic hazard of the kachchh-Saurashtra region. It drove home the possibility for multiple seismic sources in region, placing compulsions to develop models of future seismic hazard. An inventory of past earthquake is an important element in such an analysis. Palaeoseismological investigations. Ground failure, fissuring and venting associated with the Bhuj earthquake offered an excellent opportunity to examine preserved records of seismically-induced palaeoliquefaction features. Excavations in the sites of fresh liquefacitons have led to the reassertion of an older event <126> 1000 years BP and another one <126> 3000 years BP, whose sources remain uncertain.

8 illus, 2 tables, 27 ref

000383   Rajasegar M;Srinivasan M;Khan S A (Centre of Advanced Study in Marine Biology, Annamalai University, Parangipettai-608 502) : Distribution of sediment nutrients of vellar estuary in relation to shrimp farming. Indian J Mar Sci 2002, 31(2), 153-6.

Sediment composition, organic carbon, total phosphorus and total nitrogen content of sediments in Vellar estuary were studied in relation to shrimp farming. Data collected over a 2 year period showed that the nutrient rich water (due to settling of unfed feed particle) discharged periodically from the shrimp farms, did not influence much the sediment nutrients of the estuary.

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000382   Rajamani V (School of Environmental Sciences, Jawaharlal Nehru University, New Delhi-110 067) : Farmland geology - an emerging field in sustainability science. Curr Sci 2002, 83(5), 557-9.

2 illus, 1 table, 6 ref

000381   Rai A K;Srinivasan M S (Geology Dep, Banaras Hindu University, Varanasi-221 005) : Taxonomy and palaeoecology of benthic foraminiferal genus Favocassidulina from the neogene of Indian ocean. J Geol Soc India 2002, 60(2), 163-71.

Four distinctive species of the genus Favocassidulina are recorded from the Neogene deep sea sequences of seven DSDP Sites (Legs 22, 23 and 24) in the Indian Ocean. Detailed systematic descriptions and stratigraphic ranges of these species in the Indian Ocean have been provided. In addition, on the basis of quantitative faunal analysis, an attempt has been made to assess the ecological significance of the genus Favocassidulina. Species of this genus are largely confined to lower bathyal and abyssal depths and exhibit restricted occurrences in Indian and Pacific Oceans only. The intervals of higher relative abundances of genus Favocassidulina during Neogene possibly reflect low organic carbon input in the bottom waters.

4 illus, 2 tables, 30 ref

000380   Radhakrishna T;Arora B R;Mahadevan T M;Gupta K R (NO, Centre for Earth Science Studies, Thiruvananthapuram-695 031) : Palaeomagnetism and rock magnetic research in India. Curr Sci 2002, 83(1), 14-15.

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000379   Pattan J N (NO, National Institute of Oceanography, Dona Paula-403 004, Goa) : Volcanic ash and its enigma: a case study from the central Indian ocean basin. J Geol Soc India 2002, 60(2), 127-30.

An ash layer occurs between 10-35 cm depth in sediment cores from the Central Indian Ocean basin, Morphology, major, trace and rare earch element composition of glass shards from the ash layer suggest that the Youngest Toba Tuff of <126>74 ka from Northern Sumatra may be its source. To understand the implication of ash on the elemental distribution, a sediment core (NR-54) where abundant Youngest Toba glass shards occur at 30-35 cm depth interval, was studied. The presence of ash layer resulted in the enrichment of coarse fraction (260 percent), Al_excess (104 percent), K (43 percent) and Al/Al+Fe+Mn (28 percent), and depletion of Mg (58 percent), Fe (55 percent), Mn (50 percent), Ti (44 percent) and biogenic opal (37 percent), compared to their average concentrations in the core. Therefore, precaution should be taken while studying the parameters indicative of productivity (biogenic opal, coarse fraction and Al_excess), detrital terrigenous influx (Al/Al+Fe+Mn, Ti, K and Mg) and redox sensitive metal (Mn), whose concentration is affected by the presence of glass shards from the ash layer in the sediment cores from Bay of Bengal, Central Indian Ocean basin, South China Sea basin and Western continental margin of India where the widespread Youngest Toba ash is reported.

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000378   Patel S J;Desai B G;Bhatt N Y (Geology Dep, M.S. University of Baroda, Vadodara-390 002) : Origin of air trap structures in beach-bar complex and their significance - a study from Mandvi coast, Gulf of Kachchh, Western India. J Geol Soc India 2002, 60(4), 391-9.

Mandvi coast in the Gulf of Kachchh, Western India, reveal that the relative mobility of the sediments on beach-bar complex by flood and ebb tide along with te groundwater fluctuation causes trapping of air in different sediment layers. This entrapment of air produces various types of air trap structures (i.e. sand domes, mound and pits, sand holes, and bubble sands/cavernous sane). Thickness of freshly deposited layer, difference in grain size of surface-subsurface sediment layers and the slope of the beach control the formation of air trap structures. Preservation of these structures close to the high water zone is useful in delineating microenvironment of the beach-bar complex.

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000377   Pant P C;Chakrabarti K;Rawal N;Hansda P K (NO, Atomic Minerals Directorate for Exploration and Research, Eastern Region, AMD Complex, Khasmahal, Jamshedpur-831 002) : Petrography, geochemistry and intrusion mechanism of a Deccan trap dyke within the infratrappeans of Temriya area, Dhar district, Madhya Pradesh. J Geol Soc India 2002, 60(4), 381-9.

The Cretaceous infratrappean sedimentary rocks in Temriya area, Dhar district, Madhya Pradesh are intruded by Deccan Trap dykes and sills. Petrochemistry reveals that the dyke rocks are basaltic in composition, have tholeiitic affinity (Ol and/or Qz normative), continental-within plate characters showing moderate iron-enrichment with Mg. No. ranging from 0.28 to 0.42. The dyke shows variable major and trace element concentraiton and ratios; TiO₂: 2.05-2.91 percent, K₂O: 0.71-0.95 percent, Ba: 183-346 ppm, Nb: <60>5-19 ppm, Sr: 195-285 ppm, Zr: 39-124 ppm, Y: 20-32 ppm and Rb: 28-38 ppm with MgO varying from 3.01 to 5.68 percent indicating that the magma was subsequently contaminated by selective addition processes from the crust. The rocks show a moderate range in REE abundances and La/Yb ratios with a conspicuous LREE enrichment and HREE depletion. The dyke is genetically related to the Deccan Trap volcanism and was derived from a single source emplaced along tensional fractures probably due to the reactivation of basement lineaments.

8 illus, 2 tables, 36 ref

000376   Panneerselvam A;Rao J S;Chaki A;Bagchi A K (Atomic Energy Dep, Atomic Minerals Directorate for Exploration and Research, Bangalore-560 072) : Note on the uranium mineralisation in the quartzites of Kuladera area, Sambalpur district, Orissa. J Geol Soc India 2002, 60(5), 559-62.

Uranium mineralisation has been discovered recently in quartzites near village Kuladera, 15 km ESE of Bamra, Sambalpur district, Orissa. The radioactive quartzites are occurring at the base of the meta-sedimentary sequence, which is unconformably resting over the unclassified granitoids/gneisses of late Archaean age. Two mineralized quartzite bands, separated by a basic body of epidiorite/amphibolite, have been identified. The samples radiometrically assayed 0.018 to 0.15 percent U₃O₈ and are free of thorium. The uranium minerals identified are uraninite, gummite, torbernite and U-Ti complex. The other mineral phases contributing to the radioactivity are metamict allanite, zircon, anatase, limonite, epidote and goethite. The samples also analysed higher concentration of Ti, V, Cr, Zr, Cu, Mo, Pb and Ag. As the uranium mineralisation is at the unconformity between the Proterozoic metasediments and basement crystallines, it opens up a new and promising potential target area in this part of Orissa for uranium exploration.

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000375   Pandey D N (NO, Indian Institute of Forest Management, Bhopal-462 003) : Global climate change and carbon management in multifunctional forests. Curr Sci 2002, 83(5), 593-602.

Fossil-fuel burning and deforestation have emerged as principal anthropogenic sources of rising atmospheric CO₂ and consequential global warming. ariability in temperature, precipitation, snow cover, sea level and extreme weather events provide collateral evidence of global climate change. Recent advances on causes and consquences of global climate change and its impact on nature and society has been reviewed. Also options for climate change mitigation has been examined. Impact of climate change on ecology, economy and society is increasing. Emission reduction is also politically sensitive for economic reasons. Proposals of the geoengineering for iron fertilization of oceans or manipulation of solar flux using stratospheric scatters are yet not feasible for scientific and environmental reasons. Forests as carbon sinks are required to play a multifunctional role that includes, biodiversity conservation and maintenance of ecosystem functions; yield of goods and services to the society; enhancing the carbon storage in trees, woody vegetation and soils; and providing social and economic well-being of people. Explores strategies in that direction and concludes that the management of multifunctional forests over landscape continuum, employing tools of conservation biology and restoration ecology, shall be the vital option for climate change mitigation in future.

^iia2 illus, 4 tables, 129 ref

000374   Negi G C S (NO, G.B. Pant Institute of Himalayan Environment and Development, Kosi-Katarmal, Almora-263 643) : Hydrological research in the Indian Himalayan mountains: soil and water conservation. Curr Sci 2002, 83(8), 974-80.

Conservation and optimal use of soil and water resources is of prime importance. In the Indian Himalayan region (IHR), soil and water conservation programme relies upon engineering measures. Hydrological research was initiated at different locations in the IHR. A review of published literature on micro-scale (run-off-plot level) and meso-scale (watershed level) studies on hydrology in the IHR suggests that forests and a few micro-watersheds in the Central Himalayan region have been investigated. Studies reveal that grasslands lose more water; jhum cultivation loses both soil and water of greater magnitude, and forested land use loses smaller quantities of both soil and water. Lack of uniform methodology, proper instrumentation and logistic facilities influence the data collected and do not lead to any definite conclusion with regard to effect of a particular land use/vegetation type desirable for soil and water conservation.

2 tables, 75 ref

000373   Naskar D C;Choudhury K;Roy K K;Singh O P; Majumdar R K (Central Geophysics Div, Geological Survey of India, Kolkata-700 016) : Geophysical approach for delineation of shallow crustal structure along Borgaon-Sanwer transect, Madhya Pradesh. J Geol Soc India 2002, 60(2), 173-81.

Geoelectrical survey using direct current Schlumberger and equatorial dipole-dipole resistivity sounding techniques and collinear dipole-dipole traversing have been carried out along Borgaon-Sanwer profile in Madhya Pradesh. The area is covered by Deccan basalts overlying the Gondwana, Vindhyan and Bijawar sediments and the basement of Bundelkhand granite. The traverse, having a length of about 160 km, cuts across the Narmada river near Omkareswar. 2d model of 1D interpretation of Schlumberger and equatorial dipole sounding data reveals that the thickness of Deccan Trap varies from a few tens of metres to more than one km. Bundelkhand granite marks the high resistivity basement. Formations of intermediate to low resistivity are the Gondwana, Vindhyan, Bijawar and Quaternary sediments. A fault at Chhaigaon-Makhan has been delineated from the plot of resistivity pseudo-section, which is also corroborated by the findings of spectral analysis of magnetic data. 2D modelling of magnetic data has also confirmed the presence of the fault. The interpretation has also brought out the variable thickness of Deccan Trap between Borgaon and Deshgaon of 200 m to 990 m. Interpretation of the sounding curves in general reveals high resistivity Bijawar rocks occurring at shallow depth of less than one km in the area south of the Narmada river, whereas to the north of the river the Bijawar occurs at a greater depth.

6 illus, 22 ref

000372   Naqvi S M;Manikyamba C;Gnaneshwar Rao T;Subba Rao D V;Ram Mohan M;Srinivasa Sarma D (NO, National Geophysical Research Institute, Hyderabad-500 007) : Geochemical and isotopic constraints of neoarchaean fossil plume for evolution of volcanic rocks of Sandur greenstone belt, India. J Geol Soc India 2002, 60(1), 27-56.

REE HFSE and ¹⁴³Nd/¹⁴⁴Nd data from Sultanpura volcanic rocks vary between CHUR (Chondrite Uniform Reservoir), primitive mantle and depleted mantle, but appear to be derived from primitive mantle and have been probably contaminated by continental crust, Although the abundance of REE varies from 2 to 12 chondrite, the patterns are smooth and flat with small negative or positive Eu anomalies as artifacts of alteration. Generally positive, but in few samples negative Nb anomalies are also found, with (Ce/Sm)_{N being near chondritic. Ti/V, Ti/Zr, Zr/Y, Sc/Y, Nb/La, Nb/Th, Nb/U, MgO/TiO2, MgO/FeO and Al2O3/TiO2 also for many samples are near chondritic, εND=+0.8649±0.00024 resembling CHUR. Th/Nb, Nb/U and some other ratios are near to those of Ontong Java and Gorgana plateaus (0.80 Ga) and the tholeiite-komatiitic sequence found in 2.7 Ga Southern volcanic zone, Abitibi belt of Canada and 2.1 Ga Birimian belt of West Africa. Collective, these data indicate that a mantle plume, derived from an enriched mantle, possibly played an important role in the oceanic volcanic sequence of Sultanpura block. Some of the HFSE follow the olivine control line, whereas other elements following the olivine control line define a narrow array tube. Formation of such array tubes on the plots of some HFSE elements and their ratios, and the scatters of HFSE/REE ratios, probably suggest dynamic melting of the plume during ascent.}

12 illus, 4 tables, 131 ref

000371   Nambiar A R (NO, Geological Survey of India, Op: Karnataka and Goa, Vasudhna Bhavan, K.S. Layout, Bangalore-560 078) : Geomorphology and geology of the Bay of Bengal and the Andaman sea. J Geol Soc India 2002, 60(4), 470-2.

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000370   Naithani A K;Joshi V;Prasad C (Geology Dep, Garhwal University, Srinagar-246 174) : Investigation on the impact of cloudburst in Tehri district, Uttaranchal - 31 august 2001. J Geol Soc India 2002, 60(5), 573-7.

The catastrophic landslides of Gona village, which took place on 31 August 2001, has been subjected to field investigation. Indicates that a combination of several factors are responsible for this tragedy, but the action of water during the cloudburst was the main triggering factor.

^ssc3 illus, 1 table, 12 ref

000369   Nagendra R;Raja R;Nallappa Reddy A;Jaiprakash B C;Bhavani R (Centre for Geoscience and Engineering, Anna University, Chennai-600 025) : Outcrop sequence stratigraphy of the Maastrichtian Kallankurchchi formation, Ariyalur group, Tamil Nadu. J Geol Soc India 2002, 59(3), 243-8.

3 illus, 13 ref

000368   Nagendra R;Nagendran G;Narasimha K;Jaiprakash B C;Nallapa Reddy A (Centre for Geoscience and Engineering, Anna University, Chennai-600 025) : Sequence stratigraphy of Dalmiapuram formation, Kallakudi quarry -II, South India. J Geol Soc India 2002, 59(3), 249-58.

A sequence stratigraphic framework is worked out for the first time for the Dalmiapuram Formation exposed in Kallakudi quarry near Kallakudi village in Tiruchirapalli District. The complete lithological succession of this formation is designated as `Dalmiapuram Sequence' of latest Albian - Cenomanian age and consists of grey shale, coral/algal limestone and bedded biostromal limestone and marl in ascending order. Grey shale rests unconformably over the Rachaean basement. This contact forms the lower sequence boundary of Dalmiapuram Sequence. The middle lithounit, the coral algal limestone rests over grey shale. This unit abruptly grades into bedded limestone/marl alternations. This abrupt termination of coral algal limestone may be due to relative sea level rise and possibly this surface represents `drowning unconformity'. The upper lithounit, which has alternating bands of biostromal limestone and marl, might indicate cycle carbonate precipitation (?Milankovich cycles). This unit is unconformably overlain by Neogene Cuddalore sandstone. This unconformity surface represents the upper boundary of the sequence. The entire Dalmiapuram Sequence appears to have been deposited as Transgressive Systems Tract (TST) deposit and got exposed as a result of basinal rise.

5 illus, 22 ref

000367   Nagar S G;Seetaramayya P;Tyagi A;Singh S S (NO, Indian Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pashan, Pune-411 008) : Estimation of daytime surface fluxes of radiation and heat at Anand during 13-17 May 1997. Curr Sci 2002, 83(1), 39-46.

An attempt has been made to estimate radiative fluxes of short wave, long wave as well as non-radiative fluxes such as sensible heat flux and the surface soil heat flux during daytime over a bare soil at a tropical station Anand (22°35'N, 72°55'E, 45.1 m asl), for the dry convective period 13-17 May 1997. The site-specific parameters such as attenuation coefficients, albedo, transmissivity, etc. are obtained with the help of observations during 2-11 May 1997. The results are compared with real time data. Comparison of estimated and observed radiative fluxes showed a good agreement. The root mean square error (rmse) is 3% for incoming solar radiation and 8% for net radiation. The sensible heat flux is in general underestimated. The surface soil heat flux values estimated by two different methods are fairly close to each other. The surface temperature estimated by Fourier's law for heat conduction shows good agreement with the observed values with rmse 5%.

12 illus, 1 table, 34 ref

000366   Mohanty S (Applied Geology Dep, Indian School of Mines, Dhanbad-826 004) : Structural evolution of Sausar group around Parseoni, Nagpur district, Maharashtra: its implication for stratigraphy. J Geol Soc India 2002, 60(3), 309-15.

Precambrian metasediments of Parseoni area belong to the Sausar Group. These comprise of quartzite, mica schist with manganese ore and marble. The metasediments of the area show evidence of three phases of folding. The early folds (F₁) are isoclinal with an axial planar cleavage (S₁). The second folds (F₂) are tight to isoclinal with axial planar crenulation cleavage (S₂). These F₂ folds have EW striking vertical axial planes and congruous pucker axis lineations. The third folds (F₃) are open upright with NS striking axial planes. an antiformal F₂ fold plunging E is mapped in the area. In the absence of any primary top-and-bottom criteria the stratigraphic succession for the area suggested by earlier workers is debatable.

3 illus, 2 tables, 20 ref

000365   Misra S;Dey S (Geological Studies Unit, Indian Statistical Institute, Kolkata-700 035) : Bihar mica belt plutons - an example of post-orogenic granite from eastern India shield. J Geol Soc India 2002, 59(4), 363-77.

A group of small isolated domical to phacolithic granite plutons of 2 to 5 km in diameter have intruded the metasedimentary rocks of Bihar mica belt (BMB), representing north-eastern extremity of the Satpura orogenic belt of central and eastern India. The metasedimetary rocks of BMB rest on the Chotanagpur gneissic complex (CGC) with an erosional base and have recorded three phases of folding (F₁, F₂ and F₃), where the first two phases are the most dominant. A re-examination of structural, petrological and geochemical data, as well as study on new Rb-Sr whole rock isotopic ages of the BMB granite plutons, suggest that they are post-orogenic in nature in relation to the evolution of the basement (Chotanagpur gneissic complex). These plutons were emplaced between the second phase of compressive deformation (F₂) of the Satpura orogeny, and before the establishment of post-compressional extension, when the regional stress pattern was likely to be transpressional or transextensional and/or mildly extensional type. The new Rb-Sr whole rock ages provided by Geological Survey of India suggest that the BMB plutons were formed between <126>1.2 and 1.0 Ga. Though the parent magma of the plutons was earlier suggested to have been generated by partial melting of the tonalite-granodiorite component of the Chotanagpur gneissic complex, a subordinate amount of BMB metasedimentary country rock is found to be involved in the genesis of the plutons.

4 illus, 3 tables, 56 ref

000364   Mishra D C;Singh B;Gupta S B (NO, National Geophysical Research Institute, Hyderabad-500 007) : Gravity modelling acros Satpura and Godavari proterozoic belts: geophysical signatures of proterozoic collision zones. Curr Sci 2002, 83(8), 1025-31.

The modelling of a gravity profile across the Satpura Fold Belt (SFB) constrained from seismic and other available information, suggests that the gravity high observed over the SFB is caused due to high-density upthrusted blocks of lower crustal rocks in the upper crust exposed in some secitons,m and the gravity low towards the south of the Central Indian Shear (CIS) is caused due to low-density rocks below the Moho. The small-wavelength gravity lows and highs south of the CIS coincide with the felsic and the basic volcanics of tholeiitic to calc alkaline-type magmetism. These signatures suggests that the SFB represents a Proterozoic collision zone between the Bundelkhand craton towards the north and the Bhandara craton towards the south, with the CIS as the suture and plausible subduction from the north to the south. A 1000-m long NE-SW gravity profile across the Godavari Proterozoic Belt (GPB) and the Dharwar Craton (DC) also shows a regional gravity high over the GPB and regional gravity low over the DC. These signatures along with contractional deformation of the Eastern and the Western GPB indicate that it represents a compressional terrane boundary between the Bhandara craton and the DC.

4 illus, 41 ref

000363   Mehrotra R C;Mandaokar B D (NO, Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226 007) : New leguminous fruit from the middle Bhuban formation of Aizawl, Mizoram. J Geol Soc India 2002, 60(4), 465-6.

Reports the occurrence of a new leguminous fossil fruit from the Lower Miocene Bhuban Formation of Aizawl, Mizoram.

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000362   Mathur U B;Pandey D K (Geology Dep, University of Rajasthan, Jaipur-302 004) : Radiocarbon dates of corals, gastropods and foraminifers from Saurashtra Peninsula, Gujarat and their implications for sea level studies. J Geol Soc India 2002, 60(3), 303-08.

High precision Acceleration Mass Spectrometry (AMS) dates of corals, gastropods and smaller foraminifers from a coral-algal stratigraphical sequence, exposed 2.73 - 4.20 m above the present msl, near Mithapur on Dwarka-Okha coast, have been reported in the present paper. The age ranges from ca. 41.2 to 18.3 ka BP. The mineralogy, petrology and δ¹³C values of the samples indicate that the dates are reliable within the limitations of the dating method. Confirmatory U/Th dating will, however, be useful to strengthen the conclusion. Since the samples are from the intraplate area of the Saurashtra Peninsula, the present position of 41.2 and 18.3 ka old sea level recorders cannot be explained by a large-scale uplift. At the same time, they cannot be taken as the records of the sea level stands of <126>40 ka and <126>18 ka BP, as the generally accepted data suggest very low sea level stands of the periods. Therefore, an epeirogenetic model is to be evolved that satisfactorily explains not only the presence of <126>40 a corals and stratigraphically superposed younger <126>18 ka sediments, but also the corals of 118 - 176 ka BP and 6 ka BP ages that co-exist at low altutides at Mithapur. For this one needs to generate more realiable dates of the area and integrate them with the geological and geophysical information.

3 illus, 2 tables, 27 ref

000361   Marechal J C;Sarma M P;Ahmed S;Lachassagne P (Indo French Centre for Groundwater Research, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Establishment of earth tide effect on water-level fluctuations in an unconfined hard rock aquifer using spectral analysis. Curr Sci 2002, 83(1), 61-4.

Short-interval water-level measurements using automatic water-level recorder in a deep well in an unconfined crystalline rock aquifer at the campus of the National Geophysical Research Institute, near Hyderabad show a cyclic fluctuation in the water levels. The observed values clearly show the principal trend due to rainfall recharge. Spectral analysis was carried out to evaluate correlation of the cyclic fluctuation to the synthetic earth tides as well as groundwater withdrawal time series in the surrounding. It was found that these fluctuations have considerably high correlation with earth tides, whereas groundwater pumping dose not show any significant correlation with water-table fluctuations. It is concluded that earth tides cause fluctuations in the water table. These fluctuations were hitherto unobserved during manual observations made over larger time intervals. It indicates that the unconfined aquifer is characterized by a low porosity.

8 illus, 2 tables, 9 ref

000360   Mahapatro T R;Sahu S;Padhy S N (Dept of marine Sciences, Berhampur University, Berhampur-760 007) : Distribution of calcium and magnesium in Gopalapur creek waters Bay of Bengal. Nat Envir Pollut Technol 2002, 1(1), 23-6.

The seasonal variations of calcium and magnesium concentrations in the surface waters of Gopalpur Creek were studied during the year 2000-2001. Calcium and magnesium concentration increased from the upper reaches of the creek (4th st.) towards the mouth (1st at.) and varied linearly with chlorinity value. Premonsoon period recorded higher values than other seasons, whereas monsoon period encountered lower value. The calculated value of Ca/Cl and Mg/Cl ratios ranged from 0.0194-0.0460 and 0.0432-0.0905 respectively. The ratios were found to be high during monsoon and low during premonsoon period.

3 illus, 9 ref

000359   Madhavaraju J;Ramasamy S;Mohan S P;Gladwin Gnana Asir N (Geology Dep, School of Earth and Atmospheric Sciences, University of Madras, Guindy Campus, Chennai-600 025) : Ooids in Sillakkudi formation of Ariyalur group of Tiruchirapalli cretaceous, Tamil Nadu: implications for origin and depositional environment. J Geol Soc India 2002, 60(3), 317-22.

An ooid-rich limestone band of Sillakkudi Formation is encountered in a well section near Ariyalur. The ooids are believed to be deposited in a marine regime. They contain berthierine as the major mineral and haematite, siderite and quartz as minor minerals. They exhibit alternate rings of berthierine and haematite which shows that these minerals were developed under changing physico-chemical conditions. The petrographical characters, mineralogy, origin and depositional environment of the ooids are discussed.

4 illus, 31 ref