Suneetha P;Ramarao Y V;Bhanu Kumar O S R U
022562 Suneetha P;Ramarao Y V;Bhanu Kumar O S R U (Meteorology and Oceanography Dep, Andhra University, Visakhapatnam-530 003) : Forecasting of tropical cyclone using QLM model over the Arabian sea. J Agrometeorol 2008, 10(Pt 2), 349-52.
Study is to predict the central pressure, vorticity, winds, around the eye of tropical cyclone and its track during 5-10 May 2004 over the Arabian Sea using Quasi lagrangian model (QLM). The main synoptic feature of it is that it caused exceptionally heavy rainfall of 117cm at Aminidivi (11.1°N/72.7°E) during the 24 hr period ending 0300UTC of 6 May. The QLM model has predicted a mean sea level pressure of 994 hPa and vorticity near the center based on the initial conditions of 6 May/00UTC and wind at 850hPa brings out a well developed cyclonic circulation with wind speeds of 40-50 knots. The model forecast indicates that the predicted storm track is very close to the observed track; it has produced the initial structure of the storm and maintained the intensity of the system. Next, forecast verification has been carried out for the geographical distance between the predicted location of the storm and the verifying position at valid hour. The QLM results highlight that the mean error of 24hrs forecast is about 146km, which increases to about 248km for 48hr forecast and 172km for 72hr forecast. Finally simulated central pressure, vorticity and winds are validated with the datasets of India Meteorological Department and satellite products and the results are promising.
5 illus, 1 table, 6 ref
Srinivasan V
022561 Srinivasan V (NO, Geological Survey of India, Op: TNPK, Guindy, Chennai-600 032, Email: v_srinivasan_geo@rediffmail.com) : Regional structural configuration and seismic pattern of `Belt of Schuppen' in northeast India. J Geol Soc India 2007, 70(5), 801-14.
Using aerial photographs followed by extensive field checks, a photo-geological map for the entire `Belt of Schuppen' of northeast India has been prepared. The 20 to 30 km wide exposed part of `Belt of Schuppen' comprises two major thrusts (Haflong-Naga thrust, Disang thrust) and three minor sub-thrusts. The Haflong-Naga thrust (frontal thrust of `Belt of Schuppen') extends NE-SW over a length of 410 km along the break in slope separating the alluvial plain in the west from the ridges of Neogene sedimentary rocks in the east. In the SW at Miyungkhor in the left bank of Jatinga River, it is terminated by Dauki fault. In the NE near Digboi, it is concealed below the alluvium. The Disang thrust (rear thrust of `Belt of Schuppen') extends NE-SW over a length of 480 km and it defines the eastern margin of Neogene basin. In the SW near Wadrengdisa, it branches out from Haflong-Naga thrust and in the NE at Bulbulia in the right bank of Noa Dihing River, it is terminated by Mishmi thrust, which extends into Myanmar as `Sagaing fault'. The major thrusts and sub-thrusts of belt `Belt of Schuppen' dip generally towards SE. Thus the `Belt of Schuppen' extends between Dauki fault in the SW and Mishmi thrust in the NE over a length of about 500 km. When the SW end of `Belt of Schuppen' moved upwards and towards east along the Dauki fault, the NE end moved downwards and towards west along the Mishmi thrust, causing its `S' shaped bending. The southern part of `Belt of Schuppen' extends along the sheared western limb of southerly plunging Kohima synform and it is seismically active. The northern truncated end at Mishmi thrust is also seismically active. There is a pronounced seismic gap in the middle part of `Belt of Schuppen'. The epicenter plots of major earthquakes of Richter magnitude ≥7 in this region reveal that the rupturing at depth which caused these earthquakes are aligned along distinct NE-SW trending parallel zones, perpendicular to the regional compression in NW-SE direction.
10 illus, 17 ref
Som S K;Jana P;Bhattacharya U;Bardhan S;Basir S R;Ghosh Roy A K
022560 Som S K;Jana P;Bhattacharya U;Bardhan S;Basir S R;Ghosh Roy A K (Earthquake Geology Div, Geological Survey of India, Eastern Region, DK-Block, Sector-II, Salt Lake City, Kolkata-700 095, Email: sksom@rediffmail.com) : Macroseismic survey of Sikkim earthquake, 14th February, 2006. J Geol Soc India 2008, 71(4), 541-50.
Moderate earthquake struck the Sikkim Himalaya on Tuesday, February 14, 2006 at 6.25 a.m. The earthquake was felt in North Bengal, Sikkim, Nepal and Bhutan. Macroseismic survey was carried out for the accessible regions of Sikkim and the northern portion of West Bengal to assesses the intensity of ground motion, the damage caused by the earthquake and also to ascertain the possible source and its orientation. The survey results show that the MSK (Medvedev-Sponheuer-Karnik) intensity varies between III to VII. The maximum intensity is found in Gangtok-Deorali-Tadong areas, which are far from the instrumental epicenters identified by USGS and IMD. Statistical procedure has been adopted for numerical weighted intensity calculation to quantify the MSK intensity and for deducing the isoseismal lines more logically. Separate macroseismic epicenter is calculated from the high MSK- intensity sites, which falls in between Deorali and Tadong. The probable orientation of the source (fault) is found to be E-W that passes through Makha village, north of Gangtok area. The damages to constructions on the terraces is much less than those constructed on other topographic forms, like slopes, ridges and low zones. Within the most damaged Gangtok-Deorali-Tadong areas, most of the buildings are located along the ridge top or along the ridge axis.
7 illus, 3 tables, 17 ref
Singh L N;Babu Lal;Singh S L
022559 Singh L N;Babu Lal;Singh S L (NO, Geological Survey of India, Western Region, , Email: lns_gsi@yahoo.com) : Seismic survey for delineation of shallow structures in the 2001 earthquake - affected areas of Anjar and Bhuj, Gujarat. J Geol Soc India 2007, 70(5), 824-8.
Shallow seismic refraction survey (Hammer source) was carried out by Geological Survey of India in Kutch district Gujarat after the devastating i.e. earthquake of 26th January 2001. The aim of the investigation was to delineate different lithological units based on their P-wave velocities in earthquake-affected areas of Anjar and Bhuj. The seismic survey carried out over 17 locations in township areas of Anjar and Bhuj has reflected two to three layer structures. In both areas, the P-wave velocity of first layer varies from 476 m/s to 1067 m/s while the velocity of second layer varies from 1091 m/s to 1892 m/s. The third layer exhibits the velocity ranging, from 1818 m/s to 4865 m/s. The first layer corresponds to loose soil; second layer to compact soil/weathered rock and third layer to weathered/bedrock. The depths given by two boreholes drilled in both areas of study are in excellent agreement with those obtained by seismic survey conducted at borehole locations. This lends additional credence to geophysical results obtained in the area. According to layer parameters deduced from shallow seismic survey, the foundation of houses in earthquake-affected areas should be below first interface/or in second layer i.e. compact soil/weathered rock to be safer.
4 illus, 1 table, 15 ref
Saha D;Dhar Y R;Sikdar P K
022558 Saha D;Dhar Y R;Sikdar P K (Applied Geology Dep, Indian School of Mines, Dhanbad, Email: dsaha002@yahoo.com) : Geochemical evolution of groundwater in the pleistocene aquifers of south Ganga Plain, Bihar. J Geol Soc India 2008, 71(4), 473-82.
Study area is spread over 1950 sq km and covers a part of Pleistocene deposits in the Ganga Plain. A two-tier aquifer system made up of sands of various grades occurs in the area and caters to the entire water demand to the tune of 0.12 MCM/sq km/year. The top 30 m of the alluvial deposits are dominated by clay, sandy clay, silt with thin lenses of sands. The latter constitutes the Shallow Aquifer, occurring under unconfined condition. The Deep Aquifer is made up of interconnected sand layers below 30 m depth, forming a potential zone, where groundwater occurs under semi-confined condition. Sluggish hydraulic conductivity in Shallow Aquifer results in higher mineralization of groundwater than in Deep Aquifer. Principal Component Analysis with 10 chemical constituents, and plots in Expanded Durov Diagram indicate distinctly different geochemical processes in Shallow and Deep Aquifers. In Shallow Aquifer the processes shaping up the chemical character of groundwater are ion-exchange, sediments dissolution, return seepage from irrigation water and rain-water infiltration. But the major processes in Deep Aquifer are leakage from Shallow Aquifer, followed by ion-exchange and weathering of silicate minerals. In the process of ion-exchange, Na+ from the aquifer matrix dominated by clays and sandy clays replaces Ca+2 in groundwater, resulting in formation of patches of calcium carbonate nodules.
8 illus, 6 tables, 22 ref
Sachan H K;Mukherjee B K;Ahmad T
022557 Sachan H K;Mukherjee B K;Ahmad T (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001, Email: hksachan@wihg.res.in) : Brine-rich hydrothermal fluid circulation in the upper level of Nidar ophiolite sequence, Ladakh: evidences from fluid inclusions. J Geol Soc India 2007, 70(5), 780-6.
Microthermometric study of fluid inclusions in gabbro from the Nidar ophiolitic sequence revealed that brine rich fluid (34-45 wt% NaCl) at the temperature of more than 400°C were predominant throughout the gabbro. High-saline fluid inclusion homogenized by halite dissolution at the temperature of 276-400°C. All the moderate to high temperature(130-390°C) inclusions are liquid and vapour dominated, commonly secondary in origin, majority having seawater-like salinity (1.7- 8 wt% NaCl).The highly saline fluid was probably derived by phase separation of hydrothermal seawater or an exsolved magmatic aqueous phase at the temperature of 250-412°C. The migration of the phase -separated along fractures resulted in segregation of the vapour and brines and preferential entrapment of high-saline inclusions at depth. These brines may have originated when seawater approached the top of the magma chamber. The subsequent fracturing of the gabbro at the temperature of 130-390°C facilitated the entry of seawater which pervasively altered the gabbro. This hydration processes resulted into the formation of secondary minerals or by mixing with phase-separated fluid, resulting in salinities two-times higher than that of seawater.
4 illus, 22 ref
Ranjeeta Devi S;Mondal M E A
022556 Ranjeeta Devi S;Mondal M E A (Geology Dep, AMU, Aligarh-202 002, Email: emondal2002@yahoo.co.in) : Provenance and tectonic setting of Barail (Oligocene) and Surma (Miocene) group of Surma-Barak basin, Manipur, India: Petrographic constraints. J Geol Soc India 2008, 71(4), 459-67.
Sandstones of sub-flysch Oligocene Barail Group and molasse Miocene Surma Group of the Surma-Barak basin (Manipur, India), developed with uplift of the Himalaya and the Indo-Burma range, are fine to medium grained and have high quartz and lithic contents relative to feldspar. Barail Group of sandstone is moderately mature both in terms of texture and composition, whereas Surma Group of sandstone is immature texturally and compositionally. Barail and Surma sandstones are sublitharenite and litharenite. The provenance of sandstone of the Barail Group is "quartzose recycled orogen" and "cratonic interior", whereas that of the Surma Group is "quartzose recycled orogen" and "transitional recycled orogen". The detritus of sandstone are mostly derived from collision-suture fold belt. Diverse lithic fragments of shale, siltstone, slate, chert, phyllite, quartzite and quartz-mica schist with few plutonic and volcanic igneous rocks suggest their derivation from a complex assemblage of sedimentary, metasedimentary and low - medium grade metamorphic source with minor plutonic and volcanic rock contribution. Petrographic studies also suggest the prevalence of humid and semi-humid climate for Barail and Surma sandstone. Modal plots on the QpLvmLms and LmLvLs diagram indicate that the Barail and the Surma sandstones were derived from the Collision suture and Fold Thrust belt source. Tectonic activity is the dominant factor controlling the nature and composition of the sandstone of this Surma-Barak basin.
6 illus, 1 table, 22 ref
Rajib Kar
022555 Rajib Kar (Geology Dep, J.K. College, Purulia-723 101, Email: rajib_kar@hotmail.com) : Superposed folding, transposed fabric growth in granulite facies condition: implications for possible hiatus in structural history in a granulite complex of the eastern ghats belt, India. J Geol Soc India 2008, 71(4), 569-581.
Granulite complex around Jenapore, Orissa bears the imprints of three deformations, of which first two (D1 and D2) are strong events and related to pervasive deformational fabrics S1 and S2 respectively. Sector-wise structural analyses reveal that regional F1 folds, product of D1 deformation, are isoclinal, reclined, while the regional F2 folds, product of D2 deformation, are upright with overall gentle easterly plunges. Also, the polyclinal and non-cylindrical nature of regional F2 prior to F3 folding is evident. This geometrical relation and certain key features such as (1) transposition / cross-cutting of early deformation fabric by later ones; (2) different modes of recrystallization during separate deformation episodes; (3) distinct deformational regime and response of materials related to deformation fabrics and (4) recrystallization of early fabric to a new one under granulite facies condition, definitely indicate a hiatus between D1 and D2 deformations.
15 illus, 1 table, 36 ref
Rai A K;Maurya A S
022554 Rai A K;Maurya A S (Earth and Planetary Sciences Dep, Nehru Science Center, University of Allahabad, Allahabad-211 002, , Email: akrai@sancharnet.in) : Paleoceanographic significance of changes in Miocene deep-sea benthic foraminiferal diversity on the Wombat Plateau, eastern Indian Ocean. J Geol Soc India 2007, 70(5), 837-45.
In the work, late Oligocene to latest Miocene (~28-6.5 Ma) deep-sea benthic foraminifera (over 149 μm size fraction) were studied from ODP sites 760A and 761B on Wombat Plateau in the eastern Indian Ocean to understand the faunal diversity pattern. The samples were commonly examined at about 0.75m interval at both the sites. The benthic foraminiferal species diversity was measured in terms of Shannon-Weaver Index [H(S)], Hurlbert's Diversity Index (S100), Alpha Index (α) and Equitability (E'), all of which show almost similar trends with few exceptions. The Miocene section at both the sites show marked fluctuations in the values of various diversity indices of deep-sea benthic foraminiferal assemblages. Distinctly low values of diversity indices across the Oligocene-Miocene transition correspond well with the higher values of benthic δ18O and δ13C reflecting relatively cold, nutrient depleted, young bottom waters which possibly indicate the influence of Antarctic Circumpolar Current (ACC) in this region. Faunal diversity reached to maximum values at both the sites near the end of Miocene climatic optimum at about 15 Ma reflecting warm bottom waters with low trophic levels. The low bottom water temperature, expansion of East Antarctic Ice Sheet (EAIS) and possibly higher trophic level appear to be responsible for less diverse fauna during the middle Miocene i.e. ~14Ma and younger. Further, decrease in the values of diversity during latest Miocene (~7.5-6.5 Ma) is suggested to be due to increased surface water productivity in response to the intensified monsoonal activity in the eastern Indian Ocean.
5 illus, 59 ref
Qadhi T M
022553 Qadhi T M (Mineral Resources and Rocks Dep, Faculty of Earth Sciences, King Abdulaziz University, P.O. Box 80206, Jeddah 21598, Saudi Arabia, Email: tqadi@kaau.edu.sa) : Geochemical evolution of rare metal-bearing A-type granites from the Aja Batholith, hail terrain, Saudi Arabia. J Geol Soc India 2007, 70(5), 714-29.
Aja Batholith, northeastern Arabian Shield, consists of five granite varieties namely: hornblende alkali feldspar granite, granophyre, arfvedsonite-aegirine alkali feldspar granite, porphyritic alkali granite and albite granite. Zircon, sphene, thorite, Samraskite, Ta-selenide, pyrochlore, fluorite, magnetite and hematite are magmatic rare-metalbearing accessory minerals. In some rock varieties, hematite is post-magmatic where local metasomatic effects are visible in varying degrees and played a significant role in the genesis of silica-hematite-rich rocks (hematosilconite). The granite varieties in the batholith are highly siliceous (SiO2 =68-75%) with high K2O (3.72-5.52%) and Na2O (2.526.25%) and low Al2O3 (8.35-13.5%), MgO (0.07-0.4%), CaO (0.17-1.5%), Ba (20-409 ppm) and Sr (6-134 ppm). The alumina saturation index (A/CNK) for most samples is < 1 while the agpaitic index is > 1 confirming their alkaline to peralkaline character. The granites have high and variable contents of Rb (81-495 ppm), Ga (20-52 ppm), Nb (10414 ppm), Zr (290-31915 ppm), Y (22-552 ppm), Sn (3-101 ppm), and total rare earth elements (362-3518 ppm). These data indicate that the Aja batholith represents post-orogenic A-type granites. The generation of their parental magma probably involved partial melting of lower crustal rocks as a result of the decomposition of F-rich biotite. Comparison of the geochemical data with many specialized rare metal-bearing granites show that the Aja granites are enriched in Nb, Ta, Sn, Zr and REE, especially the arfvedsonite-aegirine alkali granite, the albite, granite and the hematosilconite. Although the geochemical effects of metasomatism is locally visible; nonetheless, most of the chemical variations in the content of these elements appear to be the result of in situ fractional crystallization (feldspars, ferromagnesian minerals and rare metal bearing accessory phases) and fluorine complexing. The strong positive correlation of alkalis (Rb and K) that was mobile during metasomatism with elements that were not (Nb and Ta), argues strongly against metasomatic alteration in the granites. However, the hematosilconite is consistently rich in Fe, Si, Ca, Pb, Zn, Sn and poor in Na, K, Rb relative to the granites suggesting the local effect of metasomatism.
9 illus, 1 table, 73 ref
Pant P D;Kothyari G C;Luirei K
022552 Pant P D;Kothyari G C;Luirei K (Geology Dep, Kumaun University, Nainital-263 002, Email: pant_pd@hotmail.com) : Geomorphological and geological investigation of neotectonic activity of Saryu River Fault (SRF), a part of Morth Almora Thrust (NAT) in Seraghat-Basoli area in central Kumaun, Uttaranchal. J Geol Soc India 2007, 70(5), 815-23.
Significant evidences of neotectonic activity have been observed in Seraghat - Basoli area along the Saryu river valley in the Central Kumaun Lesser Himalaya. The geomorphic and structural features indicate that the Saryu River Fault (SRF) in the area has displaced North Almora Thrust (NAT) and is still active. The tectonic rejuvenation of the NAT and SRF has resulted in the development and deformation of tectonic landforms such as unpaired terraces, tectonic flats, fault scarps and triangular cones and facets. The strike slip movement along the SRF fault has resulted not only straightening of the Saryu river course but the course has also been shifted from NW-SE to almost N-S direction, particularly between Naichan and Seri. The uplift of fluvial terraces by 44 m at Nali and deposition of almost 3.5 m thick siltymud and silt at the beginning of the deposition of levee flood plain at Ara suggests that the area is tectonically active. Shifting river courses, stretching and straightening of river channels and the levee flood plain depositional environment indicate that the neotectonic activity in controlling this domain of NAT.
7 illus, 21 ref
Narasimhan T N
022551 Narasimhan T N (Materials Science and Engineering, Environmental Science Dep, , Policy and Management, 210 Hearst Mining Building, California, Berkeley, CA 94720-1760, USA, Email: tnnarasimhan@ibl.gov) : Dimensions of earth education. Curr Sci 2008, 95(5), 578-81.
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Naidu C V;Ramakrishna S S V S;Srinivasa Rao B R;Arun Kumar S V V
022550 Naidu C V;Ramakrishna S S V S;Srinivasa Rao B R;Arun Kumar S V V (Meteorology and Oceanography Dep, Andhra University, Visakhapatnam) : Upper air circulations associated with two extreme epochs in the Indian summer monsoon rainfall. J Agrometeorol 2008, 10(Pt 2), 341-4.
All-India summer monsoon rainfall during 1871-2005 is smoothed using 11-year running average technique. It reveals systematic epochal changes. The epochs of good and poor monsoons occurred around 1958 and 1969. The upper air mean and anomaly circulations associated with these extremes are examined.
2 illus, 5 ref
Murthy P S N;Chaterjee A K
022549 Murthy P S N;Chaterjee A K (NO, , C/o V.K.V. Rao, FCA, Dondaparthy, Mandavaparipeta, P.O. Visakhapatnam-530 016, Email: murthypariti@yahoo.com) : Some aspects of fixation of exploratory parameters including optimum drilling grid in the context of multivariables of secondry enriched iron ore deposits. J Geol Soc India 2007, 70(5), 846-60.
Majority of the iron ore deposits of the world in general and India in particular have originated due to the secondary enrichment of Banded Iron Formations. It is estimated that India has high grade iron ores to the tune of 9.6 billion tonnes. The geostatistical method of calculation of optimum drilling grid, is presented, in the context of multivariables and examples are presented for three iron ore deposits. Based on studies on a number secondary enriched hematite iron ore deposits, with respect to many variables, in different iron ore belts in India, an optimum drilling grid of 50-60 m is suggested. Taking an average insitu bulk density of 3.3 tonnes/ m3, the quantum of drilling works out to be 120-85 m per million tonnes of iron ore. The quantum of drilling, indicates the necessary but not the sufficient condition. An example of specifications of the ore from buyers and improvement of quality in the mineral dressing plant are presented. For deciding the grid at local level, the data of blast holes, which are drilled at a closer interval, can be used. It is stressed that always geology has to be taken into account, and if necessary a few inclined holes are to be drilled. A few adits are also suggested for the sake of completeness of exploration. It is suggested that the approach should be comprehensive rather than viewing the problem in parts.
4 illus, 9 tables, 29 ref
Masoudi M;Patwardhan A M;Gore S D
022548 Masoudi M;Patwardhan A M;Gore S D (Desert Zones Management Dep, Agricultural College, Shiraz University, Iran, Email: masoudi@shirazu.ac.ir) : Risk assessment of lowering of groundwater table using GIS for the Qareh Aghaj sub-basin, southern Iran. J Geol Soc India 2007, 70(5), 861-72.
Entire land of Southern Iran faces problems arising out of various types of land degradation of which lowering of groundwater table forms an important feature. The Qareh Aghaj sub-basin, which covers the upper reaches of Mond River, has been chosen for a test assessment of the consequences of lowering of groundwater table. The various kinds of data gathered from the records and published reports of the Ministries of Agriculture and Energy of Iran have been analyzed in the GIS mode. Attempts at evolving a model for assessing the risk of lowering of groundwater table by considering eleven indicators of the same. The risk is related more to the irrigation activity which has led to increasing the number of wells, and groundwater overexploitation during the recent years; but some natural causes like the fluctuation in annual rainfall and hydrogeological characteristics also played a role in the recharge dynamics of the aquifers. The GIS analysis has made it possible to distinguish the areas with 'potential risk' from those widespread areas that showed the 'actual risk' of lowering of water table. It helped also to identify the areas which should be chosen on priority basis for remedial measures to mitigate the impact of lowering of groundwater table.
6 illus, 9 tables, 12 ref
Luirei K;Bhakuni S
022547 Luirei K;Bhakuni S (NO, Wadia Institute of Himalayan Geology, Northeast Unit, Itanagar, Email: ashing_luirei@rediffmail.com) : Geomorphic imprints of neotectonic activity along the frontal part of eastern Himalaya, Pasighat, east Siang district, Arunachal Pradesh. J Geol Soc India 2008, 71(4), 502-12.
Geomorphology in relation with tectonics has been studied along the Himalayan frontal part around Pasighat, eastern Himalaya, Arunachal Pradesh. Squeezed between Main Boundary Thrust and Himalayan Frontal Thrust (HFT), the morphology of the area indicates significant influence by tectonic processes. The streams including the Siang River show anomalous drainage patterns whenever they cross the lineaments. Mountain front sinuosity index, and development of deeply incised narrow valleys along the front zone indicate recent tectonic movement along the HFT. Four levels of terraces are observed in the Pasighat area. Terraces show crude stratification of their constituents. Three levels of unpaired terraces are observed in Roing-Balek area. Paleochannel reconstruction suggests a gradual eastward migration of the Siang River, which shows a swing in its flow direction from N-S to present NW-SE. Drainage basin asymmetry vectors, calculated from transverse topographic profiles of two segments, suggest preferred stream migration towards northeast and southeast direction in response to northeastward and southwestward ground tilting.
10 illus, 39 ref
Jeere D S;Shashidharan K;Guha A;Khangan V W
022546 Jeere D S;Shashidharan K;Guha A;Khangan V W (NO, Geological Survey of India, Central Region, Seminary Hills, Nagpur-440 006, Email: dsjeere_gsi@yahoo.co.in) : Relationship between the soil chemistry and all water system in parts of Kuhi minerl belt area, Nagpur district, Maharashtra. J Geol Soc India 2008, 71(4), 557-68.
Study deals with the relationship between soil chemistry, surface & sub-surface water chemistry and geology of the Kuhi mineral belt, Nagpur district, Maharashtra. Water samples were collected from shallow aquifers and surface water and were analyzed for major ions and trace elements. The study was also made to assess the suitability of these waters for irrigation use. Topsoil samples were collected and analyzed for trace elements. Chemical analysis shows that majority of the groundwater of the area is calcium bicarbonate type. Statistical analysis determines high positive correlation values for cobalt and nickel in water as well as soil. The spatial distribution of Co, Ni, in soil and Co, Ni and Pb in groundwater are nearly similar. Water samples, 7 out of 46 were found un-suitable for irrigation use based on RSC, salinity hazard and Boron concentration parameters. The surface water samples of Nag River show decreasing concentration of major ions and trace elements along the flow. Based on field and laboratory observations it was found that the Nag River water is suitable for irrigation even though it contains high detergents with objectionable colour, taste and odour.
17 illus, 7 tables, 12 ref
Jayaraju N;Suryakumar I;Reddy K R
022545 Jayaraju N;Suryakumar I;Reddy K R (Geology Dep, Sri Venkateswara University, Tirupati-5177 502, Email: naddimi_raju@yahoo.com) : Foraminiferal species densities and environmental variables of Pulicat Lake, southeast coast of India. J Geol Soc India 2007, 70(5), 829-36.
Total (Dead + live) foraminiferal species have been studied for four seasons viz., pre monsoon (July-Sept), monsoon (Oct-Dec), post monsoon (Jan-Mar) and summer (April-June) in relation to ecological variables of Pulicat Lake. Total population ranges from 298 to 1480 / 100 gms of sediment with an average of 615 per sample. Living crop ranges from 20 to 240 / 100 gms with an average of 86 per sample for the whole lake. The lowest L/D ratio (4.3%) was noticed at station 19 in monsoon and the highest (54.7%) was recorded at station 29 in pre monsoon. There is no much significant difference in variability for all the four seasons with co-efficient of variation (CV) ranging from 41 to 46%. Out of 50 species recorded, only 35 had living representatives, while the rest occurred as dead. The prominent stained (live) species in the decreasing importance are Ammonia beccarii, A. tepida, Elphidium hispidulum, Quinqueloculina agglutinans, Elphidium excavatum, Quinqueloculina hadai, Q. oblonga and Elphidium milletti.The coefficient correlation values for dissolved oxygen versus living fauna in monsoon (g = 0.33) and in summer (g = -0.26) are slightly below the significance level (g=0.36) at 95% confidence level. A high positive correlation and a high inverse relationship have been demonstrated between salinity and microbiota in monsoon and summer respectively. With the increase in organic matter fauna decreased in diversity and abundance in both the seasons. It may be concluded that in the Pulicat Lake as a whole, the environmental conditions are moderately favorable for the growth and survival of benthic foraminifera.
4 illus, 1 table, 26 ref
Jafri S H;Shailaja V;Ramesh S L
022544 Jafri S H;Shailaja V;Ramesh S L (NO, National Geophysical Research Institute, Hyderabad-500 007, Email: syed1401@rediffmail.com) : Occurrence of quench plagioclase and pyroxene crystals in Sitagota mafic volcanics of Dongargarh supergroup, central India. J Geol Soc India 2007, 70(5), 787-92.
Sitagota mafic volcanics, belonging to the Khairagarh Group of Dongargarh Supergroup, are composed of numerous basaltic flows. One of these basaltic flow is characterized by the occurrence of several morphologies of quench crystals of pyroxene and plagioclase. Plagioclase shows a spherulitic pattern, while pyroxene shows elongate parallel chain, dendritic and spherulitic habits. Most of these crystals are similar to those reported from submarine basalts, lunar basalts, spinifex textured rocks and experimentally produced quench textures. The occurrence of quench crystals, in this basaltic flow suggests that these forms were produced by rapid cooling rates of the basaltic magma, approximately at 2-50° C/hr. Further, the delicate nature of these quench plagioclase and pyroxene crystals, which are confined to the upper part of the flow, suggests in situ crystallization.
4 illus, 2 tables, 22 ref
Iyengar R N;Radhakrishna B P
022543 Iyengar R N;Radhakrishna B P (Civil Engineering Dep, Indian Institute of Science, Bangalore-560 012, Email: eni@civil.iisc.ernet.in) : Geographical location of Vedic Irina in southern Rajasthan. J Geol Soc India 2007, 70(5), 699-705.
Vedic literature refers to a place or region by name Irina. In the Rgveda it appears as a locale frequented by a particular wild animal for drinking water. But with the passage of time, in the Yajurveda texts, the word acquires a negative meaning as a desert or a place devoid of water. Gradually, in the ritualistic Vedic texts Irina gets more and more associated with disaster or misfortune. The physical features associated with Irina, as described metaphorically in the Vedic texts, are analysed to identify its probable location. It is possible the word Irina is the progenitor of the Greek name (gulf of) Eirinon of Periplus which is presently designated as the Ran-of-Kutch. During the Rgveda period Irina was in all probability, situated a little north of the Ran-of-Kutch. Available data indicates its location in the Luni-Jawai plains west of the Aravallis, in Rajasthan. The small town Erin.pura (25° 5' N, 73° 3' E) appears to retain memories of the Vedic Irina.
1 illus, 20 ref
Gaur A S;Khedekar V;Ramalingeswara Rao B
022542 Gaur A S;Khedekar V;Ramalingeswara Rao B (NO, National Institute of Oceanography, Dona Paula, Goa-403 004, Email: asgaur@nio.org) : Elemental oxides analysis of the medieval period glazed ware from Gogha, gulf of Khambhat, Gujarat, India. Curr Sci 2008, 95(5), 670-4.
During an inter-tidal zone exploration in the Gulf of Khambhat region, a large number of glazed and non-glazed sherds were recovered along with stone anchors dating back to the late medieval period. Four representative specimens were analysed for elemental oxides using scanning electron microscope and energy dispersive spectrum. The results indicate that silicon oxide content of the glazed sherds varies between ~73 and 77%, forming three-fourths of the total composition, while it ranges from 42 to 47.5% in non-glazed sherds. Its content is more than half that in the ordinary sherds. It is difficult to understand the origin of these sherds on the basis of chemical analysis, as this study focuses only on the Gogha area. Therefore, similar studies from different regions in the Gulf of Khambhat will help to understand the origin and divergence in the manufacturing techniques used.
3 illus, 1 table, 13 ref
Dey S;Gajpathi Rao R;Veerabhaskar D;Anjan Chaki;Baidya T K
022541 Dey S;Gajpathi Rao R;Veerabhaskar D;Anjan Chaki;Baidya T K (NO, Atomic Minerals Directorate for Exploration and Research, Begumpet, Hyderabad-500 016) : Geochemistry of shales from the proterozoic intracratonic Kaladgi-Badami Basin, Karnataka, southern India as an indicator of palaeoweathering and evolution of the Dharwar craton. J Geol Soc India 2008, 71(4), 483-501.
Shales of the Proterozoic Kaladgi Supergroup, occupying the intracratonic Kaladgi-Badami Basin in the Dharwar craton, are analyzed for mineralogical as well as major and trace element compositions. Field setting and elemental ratios, critical to provenance, indicate (1) major contribution from highly weathered Archaean silicic source rocks like Peninsular Gneiss and Closepet Granite, (2) the shales lack any systematic time-dependent variation of composition and (3) they record normal weathering history. Compared to the middle Archaean cratonic shales of the Dharwar craton, the Kaladgi shales are enriched in K2O, Th, La, Ce and Yb and depleted in MgO, Cr and Ni suggesting secular change in the upper crustal composition towards more felsic nature. The middle Archaean shales document acid leaching as an important weathering process, whereas the Kaladgi shales reflect intense weathering of the source similar to that of present day warm humid climate. In contrast to the extreme variability of the middle Archaean shales, the Kaladgi shales show smaller compositional variation suggesting development of larger platformal environment suitable for repeated recycling and efficient mixing. During late Archaean crustal growth, emplacement of juvenile granites into the crust and subsequent intracrustal melting has transferred huge amount of incompatible elements into the upper continental crust. The effect of this change is clearly imprinted in the evolved composition of the Kaladgi shales.
13 illus, 5 tables, 69 ref
Desai B G;Patel S J
022540 Desai B G;Patel S J (Geology Dep, The Maharaja Sayajirao University of Baroda, Vadodara-390 002, Email: bhawanigd@rediffmail.com) : Trace fossil assemblages (Ichnocoenoses) of the tectonically uplifted Holocene shorelines, Kachchh, western India. J Geol Soc India 2008, 71(4), 527-40.
Kachchh coastline (Western India) displays Holocene raised beaches and moderately dewatered tidal mud with abundant mangrove trunks. These deposits contain abundant crustaceans, polychaetes and bivalve traces of subtidal to intertidal origin. Ichnologically these deposits are characterised by ichnospecies like Gastrochaenolites, Skolithos, Ophiomorpha, Polykladichnus and Thalassinoides. These structures are grouped into three ichnocoenoses, viz, Glossifungites, Skolithos and Ophiomorpha. These ichnocoenoses are interpreted as environmentally distinct group of traces of the single endobenthic community like crustacean, polychaetes and bivalves, made in the intertidal zone. They are exposed at different levels in the intertidal-supratidal zone. Raised beaches are extremely bioturbated and contain well developed Skolithos and Ophiomorpha ichnocoenoses along with soft sediment deformational structures ascribed to seismic origin, while raised mud flats comprise of Glossifungites, Skolithos and Ophiomorpha ichnocoenoses.
8 illus, 62 ref
Das S;Samui R P
022539 Das S;Samui R P (Regional Meteorological Centre, LGBI Airport, Guwahati) : Some aspects of heavy rainfall activities associated with duration and intensity of floods over NE India. J Agrometeorol 2008, 10(Pt 2), 361-4.
Ten years daily rainfall data of 23 well distributed stations over NE India have been used to study the heavy rainfall (HRF) activities over the region. The study reveals that spatial distribution of HRF is not homogeneous over the region rather it is confined to certain areas like plains of west Assam, NE Assam and adjoining Arunachal Pradesh and Barak Valley and southern parts of Meghalaya. The contribution of HRF to the mean annual rainfall over these areas is more than 35%. The frequency of HRF is the highest in the month of June.
2 illus, 1 table, 4 ref
Das B;Paul D K;Chaudhary A K;Ray A;Patil S K; Biswas S K
022538 Das B;Paul D K;Chaudhary A K;Ray A;Patil S K; Biswas S K (Geology Dep, Presidencey College, 86/1, College Street, Kolkata-700 073, ) : Petrology and geochemistry of basanite dykes and gabbro from northern Kutch, western India: implications on source rock characteristics. J Geol Soc India 2007, 70(5), 771-9.
Major and trace (including rare earth) element abundances, mineral compositions and Nd and Sr isotopic compositions have been determined for the mafic dykes (classified as basanite) and gabbro of the northern Island belt of Kutch rift basin. These are petrographically and geochemically distinct but have similar mantle normalized trace element patterns. Measured 87Sr/86Sr ratios in the mafic dykes vary from 0.70428 to 0.70593. εNd (i) varies from 0.27 to - 6.5. The isotopic compositions are broadly similar to that of Mahabaleshwar flows of western Deccan volcanic province. The geochemical character suggests the influence of fractional crystallisation in the evolution of the basanite dykes. The parent magma was enriched in K, Ti, Na and P suggesting derivations from an enriched source during the early phase of rifting. Palaeomagnetic data on the dykes show the presence of both normal polarity direction at Dm = 338°, Im=-47° and reverse polarity direction at Dm=141° and Im=34° indicating multiple intrusion. Virtual Geomagnetic Pole (VGP) for the basanite dykes differs from Deccan Super pole suggesting a magmatic event older than the main Deccan eruption.
5 illus, 4 tables, 33 ref
Bhattacharya D;Roy M;Joshi G B
022537 Bhattacharya D;Roy M;Joshi G B (NO, Atomic Minerals Directorate for Exploration and Research, New Delhi-110 066) : Three-phased temporal evolution of the Jhirgadandi granite complex, Sonbhadra district, Uttar Pradesh. J Geol Soc India 2007, 70(5), 730-44.
Field observations, petromineralogical and geochemical studies on the rocks of Jhirgadandi pluton indicate three phases of igneous activity, compositionally ranging from granodiorite, quartz-monzonite to granite. The wide spread intermediate phase of this suite shows anomalous concentration of U, Ce and Th as compared to average granite and enrichment of K, Rb, Ba relative to Zr, Nb and Y. The radioactive minerals identified are: thorite, uranothorite, allanite, monazite and samarskite. Molybdenite and chalcopyrite are the other ore minerals. Presence of REE (rare earth element) minerals, distribution pattern of LIL (large ion lithophile) elements, various elemental ratios and increasing metaluminous tendency indicate moderate degree of differentiation. Petromineralogical study of rocks suggests partial melting of a mafic source of lower crustal rocks. Geochemical data suggests that the granitic rocks of the three phases are comagmatic. Available age data together with tectonic considerations indicate that the magmatic activity is related to the development of Mahakoshal greenstone belt, which might have culminated with the emplacement of post-tectonic Jhirgadandi suite (~ 1800 Ma), possibly under the influence of a mantle plume.
15 illus, 4 tables, 33 ref
Basu A K
022536 Basu A K (NO, , 365, P. Majumder Road, Kolkata-700 078, Email: adhirkbasu@rediffmail.com) : Role of the Bundelkhand granite massif and Son-Narmada megafault in Precambrian crustal evolution and tectonism in central and western India. J Geol Soc India 2007, 70(5), 745-70.
Unified history of crustal evolution and tectonism in the Shield area in central and adjoining part of western India has been traced to pivotal roles played by the emplacement of granites in Bundelkhand and sinistral strike-slip along the Son-Narmada megafault. Reports that delayed manifestation of force of batholithic granite emplacement is a distinct possibility.
4 illus, 2 tables, 108 ref
Basavalingu B;Ganesha A V;Pasha M A
022535 Basavalingu B;Ganesha A V;Pasha M A (Studies in Geology Dep, University of Mysore, Manasagangotri, Mysore-560 006) : Experimental simulation of prograde and retrograde reactions of osumilite-bearing assembalges: relevance to Mg-Al granulites. J Geol Soc India 2007, 70(5), 706-13.
Experimental studies on the osumilite bearing assemblages relevance to Mg-Al granulites were carried out and simulated certain retrograde reaction textures. Piston - cylinder runs were conducted in the P-T range of 5-10 Kbars and 700 - 1100°C using bulk representing Al-Si rich portion of KMASH system. The phases obtained in the retrograde runs are low-cordierite, osumilite, low Al-enstatite and melt. These phases distinctly differ from the high P-T minerals of prograde runs. It is interesting to note that in retrograde runs the precursor phase phlogopite did not form, instead, high temperature osumilite persists along with cordierite and enstatite at conditions as low as 700°C and 10 Kbar. The osumilite bearing retrograde reaction textures observed in run products corroborates well with that of Mg-Al granulites of Eastern Ghat Mobile Belt.
5 illus, 3 tables, 39 ref
Zhang K J;Cai J X;Zhu J X;Huang Z J;Shen X Z
021532 Zhang K J;Cai J X;Zhu J X;Huang Z J;Shen X Z (NO, Guangzhou Institute of Geochemistry, Laboratory of Marginal Sea Geolog, Wushan, Guangzhou 510640, China, Email: kaijun@gig.ac.cn) : Early mesozoic overthrust tectonics around the Tanlu fault zone, eastern China: implications for the north and south China collision. J Geol Soc India 2007, 70(4), 584-94.
Although the NNE-trending Tanlu fault zone is overwhelmingly taken as a sinistral strike-slip fault in western literature, authors reports intense early Mesozoic overthrust tectonics around entire Tanlu. This contractional deformation around Tanlu caused the North China block and the South China block to be shortened by at least 148 km (or 74%) and 158 km (or 56%) normal to Tanlu respectively, indicating that strong North China-South China convergence occurred along Tanlu and North China does not penetrate into the sedimentary cover of the South China block. Restoration of deformation the North China block shows that prior to the collision, the Sulu belt could have been in alignment with the original Tanlu fault. Paleozoic lithofacies and paleogeographic evidence shows that there seem both the southeastern North China promontory and the eastern Yangtze promontory, the latter including whole South Korea. The mutual penetration between these two promontories led to the separation of the original Tanlu suture into present southern Tanlu and Sulu with profound deformation of eastern China including the area around Tanlu. The northern segment of the Tanlu fault zone could have been initiated when the eastern North China block to the east of the Tanlu fault was extruded northwards toward the subduction zone around the North China and Siberia blocks, due to the impact of the Yangtze eastern promontory. Simultaneously, the escape of this block could have created space in the Sulu for the transportation of the UHP rocks that could have been originally exhumed near the Dabie Shan.
7 illus, 1 table, 43 ref
Veena M P;Achyuthan H
021531 Veena M P;Achyuthan H (Geology Dep, Anna University, Chennai-600 025, Email: hachyuthan@yahoo.com) : Sediment characteristics and depositional environment of silica sand deposits of the east coast, Tamil Nadu. J Geol Soc India 2008, 71(3), 337-44.
Silica sand deposits are exposed along the East Coast, Tamil Nadu, nearly 80 km south of Chennai. The original sediment is quartz sand to feldspathic quartz sand. Soil has developed over the younger deposits. Trough cross bedding is well developed in the younger sediments. Textural analyses of silica sand were carried out for comparative study. Silica sand varies from very coarse sand (-0.25 φ to 0.5φ), medium sand (1.25φ to 2φ), fine sand (2.25φ to 3φ), very fine sand (3.25φ to 4φ) and coarse silt (4.06φ to 5φ). Fine to medium sized grains are dominant in the silica sand. The silica sand is poorly sorted; fine skewed, leptokurtic to platykurtic in characteristics. Beach and dune sediments are predominantly coarse sand with heavy minerals. The dune sediments are moderately to well sorted, fine skewed, and leptokurtic. The beach sediments are well sorted, strongly coarse skewed, and platy to leptokurtic. The sphericity and roundness values of the silica sands vary from rounded to sub rounded and are very equant. The various types of surface features are `V' shaped notches, conchoidal fractures and striations. The study shows that the depositional environment of silica sand is markedly different from the aeolian and beach environment. Bivariant plots and textural analyses of the silica sands indicate that they have been primarily deposited by fluvial action.
8 illus, 3 tables, 24 ref
Valdiya K S;Narayana A C
021530 Valdiya K S;Narayana A C (NO, Jawaharlal Nehru Centre for Advanced Scientific Research, Bangalore-682 016, Email: a_c_narayana@yahoo.com) : River response to neotectonic activity: example from Kerala, India. J Geol Soc India 2007, 70(3), 427-43.
Drainage pattern in the Proterozoic terrane of central Kerala in southwestern Peninsular India reflects control of WNW-ESE, N-S and NNW-SSE oriented lineaments, many of which are recognized as faults. Reactivation of these faults of Precambrian antiquity manifested itself in strike-slip and oblique-slip movements as evident from their demarcating straight linear hills and ridges having steep slopes or escarpments that are characterized by exposure of remarkably fresh Proterozoic rocks on rectangular planar slopes and triangular facets cut by sparse gullies or straight furrows of recent origin, swerving of rivers and streams and change of their original meandering system to the one characterized by peculiar loops, and occurrence of epicentres of historical earthquakes (numbering 60) on or close to the faults. The Quaternary sediments in the 83 km long Vembanad Lagoon, roughly paralleling a NNW-SSE trending lineament-demarcated ridge, bear testimony to intermittent subsidence and attendant drowning of the land, attracting six rivers to discharge their waters and sediments in the resulting depression, without forming deltas at their mouths.Neotectonic activity along the NNW-SSE, N-S and WNW-ESE oriented active faults is manifest in abrupt bending of all the six rivers along them, forming loops of a variety of shape, their intimate association with lacustrine clays and muds deposited in the past, and the present-day ponding of rivers and their tributaries upstream of the crossing of the active faults. Extending upstream for hundreds to thousands of metres - as much as 4 to 7 km in a few cases - the stagnant bodies of water in the river and stream channels imply continuing movement along faults of the Proterozoic terrane.
11 illus, 54 ref
Tripathy S K;Jeere D S;Bandyopadhyay B K
021529 Tripathy S K;Jeere D S;Bandyopadhyay B K (NO, Geological Survey of India, Marine Wing, Salt Lake, Kolkata-700 091, Email: sktripathy_gsi@yahoo.co.in) : Geochemistry of stream sediments and its relation with bedrock geology in parts of Sindhudurg district, Maharashtra. J Geol Soc India 2008, 71(3), 397-406.
Geological mapping (1:25,000) and stream sediment sampling (I km x I km grid) were carried out simultaneously in parts of Sindhudurg district, Maharashtra during the year 2001-02. The area is occupied by gneisses, granites, and low-grade supracrustals of possible Late Archaean age, Neo-Proterozoic Badami sediments, Deccan Trap basalts and extensive laterites. Deals with the spatial distribution patterns of selected major oxides (Fe2Ot3, Al2O3, P2O5, MnO and MgO) and trace elements (Co, Ni, Cr, Zr, Sr, Rb and Ba) in stream sediments in relation to the underlying rock outcrops. The study area has neither large-scale anthropogenic activities nor any reported mineral occurrence. In such terrains, the study reveals that the spatial elemental distribution in stream sediments is mainly guided by the bedrock geology and chemistry. A gabbroic body in the central part of the area is reflected remarkably well in the high value stream-sediment contours of Co, Ni & Cr and matches fairly well with elevated values of Fe2Ot3, MgO and MnO. Stream sediment samples over younger granites are rich in Zr, Ba and Sr. The elemental concentrations in stream sediments over gneissic rocks show moderately high values of Ba, Sr, Zr, Al2O3 and low values of remaining elements. Cluster analysis of the dataset reveals three groups within the elements discussed above, viz. Group I (Cr-Co-Ni-Mg-Mn), Group II (Ba-Sr-Zr-Rb) and Group III (Al-Fe-P). Group-I elements are concentrated and depleted in ultramafic-mafic rocks and acid rocks respectively while Group II elements are depleted in mafic rocks but enriched in acid and alkaline rocks. Group-Ill elements show minor affinity towards both acid and basic rocks. Therefore, in a terrain occupied by varied rock units, stream sediment sampling is required to be dense enough to represent the changing lithology. A gneissic terrain requires a much denser sampling programme compared to an area occupied by Deccan Traps.
11 illus, 2 tables, 6 ref
Tiwari R P;Malsawma J;Sangode S J;Arora B R
021528 Tiwari R P;Malsawma J;Sangode S J;Arora B R (Geology Dep, Mizoram University, Aizwal-796 009, Email: rptiwari84@rediffmail.com) : Magnetostratigraphy of a part of middle Bhuban sequence (Surma Group), Aizawl, Mizoram. J Geol Soc India 2007, 70(4), 667-74.
560 m thick rock succession of Middle Bhuban Formation (Surma Group) exposed between Bawngkawn and Durtlang, Aizawl, Mizoram has been studied for its magnetostratigraphic attributes. A total of 7 normal and 7 reverse magneto-zones have been delineated in this section. The GPTS correlated ages of this section lie between ~21.77 Ma (at the base) to ~15.16 Ma (at the top) with a total duration of ~ 6.6 Ma. The GPTS event C6n occurring at the stratigraphic level between 146m to 266 m may be considered for basin wide correlation as it is the longest normal event that has been recorded with greater confidence i.e. better alpha- 95. The average sediment accumulation rate (SAR) estimated for this section is 8.48 cm/Ka. Overall the SAR is higher in the lower part of the section with a spike of 26.8 cm/Ka at <21 Ma. The decrease in SAR to 2.1 cm/Ka at around 18 Ma in the upper part of the section may be investigated for possible hiatus.
4 illus, 3 tables, 39 ref
Sunder Raju P V;Merkle R K W
021527 Sunder Raju P V;Merkle R K W (NO, National Geophysical Research Institute, Hyderabad-500 007) : Native platinum, chromite and Fe-Ni sulphide in Sittampundi anorthosite complex. J Geol Soc India 2007, 70(4), 680-2.
^ssc2 illus
sulabha v;Prakasam V R
021526 sulabha v;Prakasam V R (Dep of Environmental Sciences, University of Kerala, Kariavattom, Thiruvananthapuram-695 581) : Limnological characteristics of Asramam Temple Pond of Kolam Municipality, Kerala. Indian J envir Prot 2008, 28(12), 1093-8.
Asramam temple pond. associated with Sree Krishna Swamy Temple, is located in Kollam Municipality. Physico-chemical characteristics of water and sediment, primary productivity, phyto and zooplankton counts, coliform count and correlation coefficient of various parameters were analysed for a period of one year from June 1999 to May 2000. Higher primary productivity and high phytoplankton counts were the characteristics of Asramam pond. The pH, chloride, phosphate, nitrate, iron, sodium and potassium of water; sediment pH and sediment nitrate; primary productivity and zooplankton count recorded higher values during non-rainy season. Total and faecal coliforms registered higher values during monsoon season. Thirty four genera of phytoplankton belonging to Cyanophyceae, Chlorophyceae and Bacillariophyceae and seven genera of zooplankton belonging to Rotifera, Copepoda and Cladocera were recorded. A comparison of water characteristics of Asramam pond with BIS desirable limits for drinking and swimming water indicated that turbidity, colour, pH and coliform count exceeded the desirable limit. The interrelationships of various water and sediment parameters are also pointed out in the study.
1 table, 25 ref
Srivastava D C;Shah J
021525 Srivastava D C;Shah J (Earth Sciences Dep, IIT Roorkee, Roorkee-247 667, Email: dpkesfes@iitr.ernet.in) : Limitations of conjugate fractures and scope of reactivated faults in palaeostress analysis. J Geol Soc India 2008, 71(3), 303-12.
Reviews the conditions that must be satisfied for application of the Anderson's law to decipher the orientations of the principal stresses from conjugate pairs of shear fractures/faults. It shows that the reactivated faults and fractures are more powerful stress indicators than the Andersonian fractures, because the former can reveal not only the orientations of the principal stresses, but also the relative magnitudes of the principal stresses in terms of the shape of the stress ellipsoid. A few commonly used graphical and numerical methods for palaeostress analysis from the reactivated faults are evaluated critically. Finally, the significance of relative magnitudes of the principal stresses is demonstrated with an example of the striated faults cutting through the Amritpur granite in the Kumaun Lesser Himalaya.
10 illus, 24 ref
Singh R N
021524 Singh R N (NO, National Geophysical Research Institute, Hderabad-500 007, Email: rnsingh@ngri.res.in) : Modeling erosion induced subsurface thermal changes and tectonic consequences. J Geol Soc India 2007, 70(3), 489-98.
Erosion has been a dominant geological process. Erosion of the continental crust removes surface layers bringing hotter regions closer to the surface. Eroded surface layers also have larger radiogenic heat production. Effects of both these on the thermal evolution of crust have been earlier modelled analytically with the help of an advection-diffusion equation model. These processes lead to raising thermal gradient near the surface initially and decreasing later on depending on the rate of erosion. The changes in the thermal structure of the near surface region would lead to generation of thermal stresses, changes in the depth of brittle-ductile transition and lateral mass transport below this transition depth. Analytical models developed to quantify thermal effects due to erosion have been summarised and some numerical results, applicable to the south Indian region, are presented.
4 illus, 1 table, 31 ref
Singh R K;Rajesh Prakash;Shukla A K;Bhatnagar A K;Srivastava H N
021523 Singh R K;Rajesh Prakash;Shukla A K;Bhatnagar A K;Srivastava H N (NO, India Meteoroligical Dep, New Delhi-110 003) : Seimicity pattern preceding great Muzaffarabad earthquake of 8th October 2005. J Geol Soc India 2008, 71(3), 388-96.
Seismicity pattern has been examined prior to the occurrence of the six earthquakes (M ≥ 5.4) during the period 1965 to 2005. This includes the damaging earthquake of Gilgit 1972, Pattan 1974 and Muzaffarabad earthquake 2005. The results were interpreted with reference to (i) pattern of occurrence of past earthquakes (ii) energy released event wise and cumulative energy released year wise. All these earthquakes were preceded by quiescence followed by increase in seismicity before the occurrence of main earthquake. An alternative interpretation of the data prior to the occurrence of the great Muzaffarabad earthquake (October 2005), suggested a sequence of double quiescence as reported in Uttarkashi (1991) and Chamoli (1999) earthquakes in Uttaranchal. The focal mechanism solution of an earthquake during February 2004 and October 2005 revealed significant changes in the orientation of P and T axis. It was interesting to find that the value of W in Gutenberg-Richter frequency magnitude relationship decreased markedly during 1985-1994 and almost recovered prior to the occurrence of Great Muzaffarabad earthquake in accordance with the Dilantancy Diffusion model of earthquakes.
6 illus, 2 tables, 13 ref
Singh A D;Nisha N R;Ramachandran K K
021522 Singh A D;Nisha N R;Ramachandran K K (Dep of Geology, Banaras Hindu University, Varanasi, Email: arundeosing@yahoo.com ) : Late quaternary evolution of the shelf environment off north Kerala faunal and sedimentological evidence. J Geol Soc India 2007, 70(1), 109-20.
Four gravity cores from the shelf off the southwest coast of India were studied in detail for various micro-faunal and sedimentological parameters, The study enabled to establish chronostratigraphic subdivisions in two late Quaternary outershelf sediment cores using stable oxygen isotopes, foraminiferal and pteropod records and lithological characteristics combined with the radiocarbon dates, The innershelf cores display two distinct benthic foram,iniferai biofacies and corresponding lithofacies representing the late Pleistocene and the Holocene periods, The investigation indicates that the planktic foraminiferal benthic foraminifera ratio, pteropods/planktic foraminifera ratio, absolute;' abundance, species diversity and epifaunallinfaunal ratio in benthic foraminiferal population can be potential criteria for biostratigraphic subdivisions in shelf sedimentary records which are mainly expressions of past changes in sea, level and environmental conditions, Down-core variation in benthic foraminiferal records reflects changes in bathymetry' and environmental conditions associated with sea level variation and glacial-interglacial boundary conditions in the last 23 kyr. Foraminiferal and sedimentological records further indicate a probable existence of paleoestuary in the study area.
8 illus, 1 table, 49 ref
Shrivastava J P;Pujari G N
021521 Shrivastava J P;Pujari G N (Geology Dep, University of Delhi, Delhi-110 007, Email: jps1815@yahoo.com) : Cu-Mo anomalies in the deciduous, semi-deciduous and evergreen taxa associated with the Malanjkhand granitoid, Madhya Pradesh. J Geol Soc India 2007, 70(4), 641-57.
Deciduous, semi-deciduous and evergreen taxa present over the Malanjkhand granitoids show variations in the spatial distribution patterns - Terminalia alata and Ougeinia oojeinensis are the most abundant and moderately abundant plant species in the Pipardhar and Dhorli areas respectively, whereas, Shorea robusta predominating in the Pathratola area. The spatial spread of biogeochemical anomalies, based on Cu and Mo data, obtained from leaves, twigs and bark of eighteen species, overlap soil Cu and Mo anomalies in Pipardhar area. The Cu anomalies, based on twig, bark, and leaf samples, when compared with the soil Cu anomalies, show lateral displacement. In Pathratola area, plant and soil Cu anomalies do not overlie each other. The anomalous Cu values were recorded in Terminalia alata leaves and Shorea robusta bark and leaves, which grow over soils having background Cu concentrations. The deep-rooted large trees of Terminalia alata, Ougeinia oojeinensis and Casearia graveolens are indicative of buried mineralisation. In Pipardhar area, Cu and Mo anomalies for twigs, cover more or less same areas, which largely corresponds to soil Cu anomaly. The increase in the Cu / Mo contents of the plant organs with the corresponding increase in their substrate soil metal contents, having high correlation coefficient values, found in Terminalia alata, Ougeinia oojeinensis, Adina cardifolia, Diospyros melanoxylon, Shorea robusta, Anogeissus latifolia, Buchanania lanzan, Casearia graveolens, Casearia tomentosa, and Pometia pinnata. The Terminalia alata indicate high toxic thresholds for Cu and Mo both, whereas, Ougeinia oojeinensis and Shorea robusta show very high toxic thresholds for Mo only. These limits are significant and pointing towards the presence of Cu-Mo enriched substrate. A significant relationship was also observed between mean values of plant metal of all the organs of Casearia tomentosa, Diospyros melanoxylon, Anogeissus latifolia, Casearia graveolens, Ficus glomerata, Lagerstroemia parvifolia, Mitragyna parvifolia, Petrocarpus marsupium, and Schleichera oleosa, versus soil metal contents. Moreover, some organs of Terminalia alata, Ougeinia oojeinensis and Shorea robusta show significant relationship. These revelations are congruent with the prolific abundance of Terminalia alata, Ougeinia oojeinensis and Shorea robusta over the Cu anomalies.
8 illus, 4 tables, 38 ref
Sharma V K
021520 Sharma V K (NO, Geological Survey of India, Northern Region, Lucknow-226 024, Email: vksharma_gsi@yahoo.co.in) : Macro-zonation of landslide hazard in the environs of Baira dam project, Chamba district, Himachal Pradesh. J Geol Soc India 2008, 71(3), 425-32.
Landslides are the most common geo-hazard in hilly terrain. Developmental activities have been hampered to a great extent by phenomenon of landslides. The construction of Baira dam on River Baira remained suspended nearly for two years on account of a major landslide. An assessment of landslide hazard is, therefore, a prerequisite for sustainable development of the region. The study deals with macro-zonation of landslide hazard in an area of about 100 sq km on 1:50,000 scale encompassing Baira dam. A numerical weightage to the prime causative factors of slope instability viz. lithology, structure, slope morphometry, relative relief, land use and groundwater conditions are assigned as per the scheme approved by Bureau of Indian Standard for the purpose of landslide hazard zonation. The area depicts zones of different instability. The identified hazard zones compared with isopleth mapping of landslide intensity in the area show mismatch of the hazard zones. This anomaly calls for further rationalization of the numerical weightages of the assigned factors.
9 illus, 2 tables, 11 ref
Sharma R;Rameshwar Rao D
021519 Sharma R;Rameshwar Rao D (NO, Wadia Institute of Himalayan Geology, 33, Gen, Mahadeo Singh Road, Dehradun-248 001, Email: sharmarajesh@wihg.res.in) : Stannoidite and cubanite from askot polymetallic sulphide ores, Kumaun lesser Himalaya, India. Curr Sci 2008, 95(4), 527-31.
Results of mineral, chemical and XRD investigations on stannoidite and cubanite from Askot sulphide deposit, Kumaun Himalaya are presented here. Stannoidite occurs as myrmekitic intergrowth and cubanite as ex-solved lamellae in chalcopyrite. Chemical composition of this tin-bearing sulphide closely matches that of stan-noidite, hitherto unreported from the Himalayan sulphides. Stannoidite and cubanite from Askot are non-stoichiomctric. An average of 1.13 wt% Zn is present in stannoidite, whereas the zinc content of cubanite is very low. Cu/(Cu + Fe) ratio of about 0.326 in cubanite indicates iron enrichment. These sulphides were formed from cooling of high-temperature hydrother-mal solution, possibly with higher sulphur fugacity.
2 illus, 3 tables, 34 ref
Shah J;Srivastava D C;Pandian M S;Sarkar S; Choudhari M;Subramanian V
021518 Shah J;Srivastava D C;Pandian M S;Sarkar S; Choudhari M;Subramanian V (Earth Sciences Dep, IIT Roorkee, Roorkee-247 667, Email: dpkesfes@iitr.ernet.in) : Mesoscale fractures as palaeostress indicator: a case study from Cauvery basin. J Geol Soc India 2007, 70(4), 571-83.
Study presents the results of field studies, and palaeostress analyses of the mesoscale fractures and veins in Cauvery basin. It shows that different sedimentary sequences (119 - 64 Ma) are cut by tensile structures that belong to two successive phases of post-Palaeocene brittle tectonics, an early phase during which bedding parallel fractures and veins were developed due to horizontally directed maximum compression and vertical extension, and a late phase of hydraulic fracturing in a tectonic regime of vertically directed maximum compression. Dynamic analyses imply triaxial and axial compression deviatoric states of palaeostress during first and second phases of fracturing, respectively. Very high pore-fluid pressure and low differential stress, during the second phase of fracturing, resulted into hydraulic brecciation as a consequence of simultaneous extension in different orientations. Suggests that the development of the mesoscale extensional (mode 1) fractures in Cauvery basin is due to reactivation of large-scale normal faults in the basement rocks.
9 illus, 1 table, 29 ref
Sarkar S;Khonglah M A;Khan M A;Ray J N
021517 Sarkar S;Khonglah M A;Khan M A;Ray J N (NO, , North Eastern Region, Shilling-793 003, Email: subratasark_11@rediffmail.com) : Polymodal Occurrence of early mafic differentiate associated with mid-proterozoic Calc-alkaline plutons of Meghalaya. J Geol Soc India 2007, 70(1), 53-8.
Early mafic differentiate of quartz diorite to quartz monzodiorite composition related to Mid-Proterozoic, late- to post-tectonic calc-alkaline (diorite-granodiorite) plutons in Meghalaya occur in three different modes, viz. (I) dykes in country rock gneisses along tectonic locales, (2) endogenous inclusions in the diorite-granodiorite intrusive plutons, as early differentiated product through fractional crystallization or liquid immiscibility, and (3) xenoliths in Upper Proterozoic-Early Palaeozoic granite plutons (Nonpoh granite). These appear to be basic precursors of the granitoids. The mafic inclusions were subjected to metasomatism by granitoids over an extended period starting with the formation of the granitic differentiates of calc-alkaline instrusions and ending with the placement of the later granitic plutons. Petrology and chemistry of the mafic rocks suggest a possible basic parentage.
13 illus, 2 table, 8 ref
Ravi S;Satyanarayana S V
021516 Ravi S;Satyanarayana S V (NO, Geological Survey of India, Bandlaguda, Hyderabad-500 068, Email: iyers_ravi@rediffmail.com) : Discovery of kimberites in Chagapuram area, Mahaboobnagar district, Andhra Pradesh. J Geol Soc India 2007, 70(4), 689-92.
^ssc4 illus, 6 ref
Ramkumar M U
021515 Ramkumar M U (Geology Dep, Periyar University, Salem-636 011, Email: muramkumar@yahoo.co.in) : Carbonate diagenesis in the Kallankurichchi formation, Ariyalur group, South India and its implications on petroleum prospects. J Geol Soc India 2008, 71(3), 407-18.
Petrographic observations on diagenesis of the Kallankurichchi Formation carbonates, supplemented by geochemical, mineralogical and stable isotopic data have delineated 5 diagenetic zones viz., sediment-water interface, marine phreatic, meteoric vadose, meteoric phreatic and meteoric closed/semi-closed system, that have acted through eo, meso and telodiagenetic stages. Though the depositional conditions could have supported extensive production of organic matter during deposition, biological organisms such as borers during deposition and extensive chemical compaction during marine burial stage diagenesis have destructed the organic matter. Repeated occurrences of dissolution-precipitation mode of diagenesis under oxygenated conditions have impoverished the rocks as poor source rocks. Prolific cementation made the formation not to be a hydrocarbon reservoir. However, owing to the occurrences of poorly cemented, loosely packed and moderately well sorted siliciclastic deposits over and below the Kallankurichchi Formation, it can serve as stratigraphic trap and/or reservoir seal if those siliciclastic deposits contain hydrocarbon reserves. It is also revealed that the viscous hydrocarbon residues found in dolomitic limestones are a localized phenomena restricted within shell cavities that escaped open system of meteoric diagenesis.
4 illus, 19 ref
Ramazi H;Haghani R
021514 Ramazi H;Haghani R (NO, Amirkabir University of Technology, Tehran, Iran, Email: ramazi@aut.ac.ir) : The 22nd June, 2002 Avej (Iran) earthquake: engineering seismology and earthquake engineering perspectives. J Geol Soc India 2007, 70(4), 610-18.
On June 22,2002 a large earthquake shook the suburbs of Avej town, Qazvin, Iran. Destroyed 7 villages (Changureh, Abdarreh, Hassan-Abad, Naqash, Niaraj, Khandab, Kartal) completely and damaged more than 80 villages between 50% and 90%. The earthquake was felt in the surrounding area up to 100 km. According to official reports, more than 261 people were killed and 1300 were wounded. Magnitude of the earthquake was assigned mb=6.0 by Geophysical Institute of Tehran University (GITU), Ms=6.0 by National Earthquake Information Center (NEIC) and Mw=6.5 by United States Geological Survey (USGS) and focal depth of the event, according to USGS report, was estimated to be 10 km. The fault plane solution showed that the event was caused by a reverse fault having trend of about N115. The main shock of the quake was recorded by 50 accelerograph stations. At Avej station, 28 km far from the epicenter, the maximum horizontal and vertical accelerations were approximately 0.50g and 0.26g, respectively. The macroseismic analyses showed that the epicenter of the earthquake was in the center of a triangle formed by Avej town, Changureh and Gun-lu villages. More intensive damages were seen in a region limited between Avaj town in the south, Abegarm village in the east, Shirinsu village in the west and Hessar village in the north. In this region all adobe buildings collapsed, masonry buildings were damaged severely and the engineered structures, which were designed and constructed according to the national seismic code for earthquake resistant structures, suffered different levels of damage. Finally the peak intensity of the earthquake in vicinity of surface rupture was estimated to be IX on the MSK scale.
17 illus, 5 tables, 16 ref
Ramasamy S M
021513 Ramasamy S M (Centre for Remote Sensing, School of Geosciences, Bharathidasan University, Thiruchirappalli-620 023, Email: smrsamy@gmail.com) : Whirling (Buckling) and fracturing Indian plate and it's consequences - a remote sensing appraisal. J Geol Soc India 2007, 70(4), 682-5.
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Rajput S;Thakur N K;Prasada Rao P;Joshi A
021512 Rajput S;Thakur N K;Prasada Rao P;Joshi A (NO, National Geophysical Research Institute, Hyderabad-500 007, Email: nkthakur46@yahoo.com) : Attenuating the seismic interference noise on three-dimensional seismic data by frequency-receiver-shot (f-x-y) prediction filters. Curr Sci 2008, 95(4), 501-4.
The potential prospects of oil/gas and gas hydrates, exploration activities in the marine environment have increased extensively. These seismic experiments however, result in contaminating the signal by interference noise which is generated due to neighbouring seismic vessels working in the same area. This noise in seismic reflection data may be substantially minimized by seismic interference noise attenuation technique. This technique utilizes frequency-receiver-shot (f-x-y) prediction filter to estimate the noise. The predicted filters can be applied in the f-X: domain to remove noisy frequencies in seismic records. We have performed this exercise on a multi-channel seismic reflection dataset and the results indicate that noise from different sources has been successfully eliminated from the recorded datasets. Study suggests that the f-x-y interference attenuation mechanism preserves the primary signal and eliminates the seismic interference in an efficient manner.
5 illus, 8 ref
Raina V K;Sangewar C
021511 Raina V K;Sangewar C (NO, , #258, Sector 17, Panchkula-134 109, Email: gauba_in@yahoo.com) : Siachen Glacier of Karakoram Mountains, Ladakh-its secular retreat. J Geol Soc India 2007, 70(1), 11-16.
The Siachen glacier is the second largest glacier known outside the polar and sub-polar regions and the largest in the Karakoram Himalaya. The glacier with a length of 74 km is an example of the nature and size of the glaciers that must have once existed in the Himalaya towards the end of the last Ice Age. This glacier, primarily, because of its size has remained an important topic of glacier study and survey. Observation of the glacier front from 1862AD till date has revealed that there may have been a rapid advance of 700 m or so between 1862 and 1909, which was subsequently neutralised by relatively faster retreat between 1929AD and 1958AD. The glacier along its snout front has since been in rest mode, a term used in glaciology to depict glaciers with very low or practically nil retreat.
10 illus,13 ref