016341   Karmalkar N R;Kale M G;Duraiswami R A; Jonalgadda M (Geology Dep, Pune Univ, Pune-411 007, Email: nrkarmalkar@gmail.com) : Magma underplating and storage in the crust-building process beneath the Kutch region, NW India. Curr Sci 2008, 94(12), 1582-8.

Not all the magma produced during the partial melting of the mantle always reaches the Earth's surface. Most of it cools and may freeze during its ascent through the lithosphere when the ascent rates are not sufficiently high. In continental flood basaltic provinces magmatic underplating is a quantitatively important mechanism of crustal growth and evolution. Beneath continental areas, likely areas to trap basaltic magmas are located near the Moho or within the crust. Seismic studies and other geophysical means have provided evidence for underplated bodies beneath the Hawaiian Islands, La Reunion, Ninetyeast ridge, and the Deccan Trap. However, the ubiquitous occurrence of cumulate xenoliths in the lavas is perhaps the best and most direct petrological evidence for the significance of magma intrusion and accumulation beneath continental areas. Review occurrence of suite of ultramafic xenoliths entrained in the alkaline lavas, especially the cumulate xenoliths from Mt. Sayala, Kutch region, Gujarat in the western part of Deccan Flood Basaltic Province, India and its implication in understanding sub-crustal level magmatic and crust-building processes. In relation to the underplating process we discuss the importance of various other igneous intrusions and their role in the tectonomagmatic evolution of this part of the Deccan Flood Basalt.

^iia3 illus, 54 ref

016340   Goswami P K;Pant C C (Geology Dep, Kumaun Univ, Nainital-263 002, Email: drpgoswami@yahoo.com) : Morphotectonic evolution of the Binau-Ramganga-Naurar Transverse Valley, Southern Kumaun Lesser Himalaya. Curr Sci 2008, 94(12), 1640-5.

The transverse river valleys in Kumaun Lesser Himalaya provide excellent transects to understand the neo-tectonic activities along various criss-crossing faults/ thrusts. Digital analysis of remote sensing data and field investigations have been carried out to understand the morphotectonic evolution of the Binau-Ramganga-Naurar river valley in southern Kumaun Lesser Himalaya. The study reveals that the basal thrusts of crystalline nappes as well as the transverse Bhikiyasain Fault are neotectonically active and directly influence the morphology and landscape of the valley.

7 illus, 14 ref

016339   Gadgil S;Rajeevan M (Centre for Atmospheris and Oceanic Sciences, Indian Institute of Science, Bangalore-560 012, Email: sulo@caos.iisc.ernet.in) : Indian Monsoon, 5. Prediction of the monsoon. Resonance 2008, 13(12), 1117-32.

Considered the importance of prediction of the monsoon, and events such as the intense rainfall event over Mumbai in July 2005. Discuss how meteorologists make short-, medium-, and long-range forecasts and the concept of the limit of predictability in a chaotic system such as the atmosphere. Problems and prospects of prediction on different time-scales are discussed by using one example of short-range forecasts and the prediction of the monsoon by dynamical and statistical methods. Finally consider measures of the skill of a forecast and how high the skill has to be for it to be useful for applications.

4 illus, 6 ref

016338   Das G K (NO, , Anwesa (1st floor), 2P/24, Jheel Road, Bank Plot, Jadavpur, Kolkata-700 075, Email: gautamkrdas@yahoo.com) : Composition of beach materials along the coastline of India. Indian Sci Cruiser 2008, 22(3), 15-23.

A long stretch of about 8129 Km length of Indian coastline registers various deposi-tional environments particularly in the intertidal zone of sea beaches. There are innumerable sea beaches in the peninsular Indian sub-continent. Sea beaches of Indian coast experience the regular effects of waves and tidal currents. Texturally the beach sediments are sandy in nature. Surface physical structures are rare in the intertidal zones of these sea beaches. Under this situation, composition of beach materials including lithogenic and biogenic constituents and their distributions would be the unique means for the interpretation of the beach characteristics along with related beach processes.So, therefore sediments from a few selected beaches along the Indian coasts namely Gangasagar, Frasergunj-Bakkhali, Chandrabhaga, Puri, Visakhapatnam, Chennai, Kovalam, Kasaragod and Mumbai for grain size analysis and micro-paleon-tological studies.

5 illus, 1 table, 3 ref

016337   Arun Kumar (Center for Petroleum and Minerals, Research Institute, King Fahd Univ of Petroleum and Minerals, P.O. Box 1945, Dhahran 31261, Saudi Arabia, Email: arun@kfupm.edu.sa) : Megatsunamis as a possible means of long distance transport of palynomorphs. Curr Sci 2008, 94(11), 1367-8.

17 ref

016336   Anbalagan R;Kohli A;Chakraborty D (Earth Sciences Dep, Indian Institute of Technology, Roorkee-247 667, Email: anbaiitr@gmail.com) : Geotechnical evaluation of harmony landslide on Karnaprayag-Gwaldam road, Uttarakhand Himalaya. Curr Sci 2008, 94(12), 1613-19.

Landslides constitute one of the major natural disasters in the fragile ecosystem of the Himalaya. Due to landslides, the Himalayan region faces major problems of geoenvironmental imbalance and poses threats to life and property. In 1986, a major landslide occurred near Harmony village on left bank of Pinder river, along Karnaprayag-Gwaldam Road, Chamoli District, Uttarakhand. This landslide is reactivated almost every year causing disruption of traffic along this important hill route and creating recurrent economic loss to the state exchequer. In view of the importance of the Harmony landslide, detailed investigations incorporating relevant engineering geological and geo-technical parameters were carried out in order to find suitable control measures.

7 illus, 2 tables, 6 ref

016335   Alam M;Rais S;Aslam M (Applied Sciences & Humanities Dep, Faculty of Engineering and Technology, Jamia Millia Islamia, New Delhi-110 025, Email: sumbulrais@gmail.com) : Hydro-chemical survey of groundwater of Delhi, India. E J Chem 2009, 6(2), 429-36.

The physicochemical parameters and trace metal contents of water samples from Delhi were assessed. A total of 20 water samples were collected from boring, tube well and hand pump and analyzed for the various physicochemical parameters like pH, conductivity, total dissolved solid, total alkalinity, Ca²⁺ and Mg²⁺ hardness, chloride ion, dissolved oxygen, biochemical oxygen demand, sulphate and heavy metal contents like Cu, Cr, Cd, Co, Zn and Ni. The results were compared with BIS standards for drinking water. The quality of water samples under study were within the maximum permissible limits. Therefore, the groundwater samples are fit for human consumption without prior treatment.

6 illus, 2 tables, 7 ref

015223   Yadvinder Singh (Geography Dep, Punjabi Univ, Patiala-147 002) : Land use and land cover related hydrological changes in different ecosystems of inter state Chandigarh region, NW India1. Trans Inst Indian Geogr 2008, 30(1), 69-84.

For assessment of the land use and land cover related hydrological changes, the Inter State Chandigarh Region covering 5,391.50 km2 area and having Chandigarh Conurbation as its core and encompassing four different ecosystems has been taken into consideration. Settlement pressures, rapidly declining land reserves for extension of agriculture and growing population led to forest destruction in the Natural Hilly Ecosystem of the Siwalik Hills. Meeting highly accelerated timber-fuel-fodder requirements led to marked changes in the vegetal cover. Cessation of inception effect due to forest clearance and gradual reduction in the humus cover resulted in low infiltration and in turn increased surface run off downstream in Semi-Natural Drainage Ecosystem. Thus the barren hills exhibit signs of rapid soil erosion and present 'badland' topography of the Siwalik Hills. The result is sedimentation of stream channels. The rapid siltation process is well illustrated by Sukhna Lake in Chandigarh. In the piedmont and upland plains the water run off increased since 1950 when the agricultural region with forests in the adjoining Siwalik Hills, was put to totally different use in the developing Heterotrophic Urban Industrial Ecosystem. Constructions related to urban growth progressively sealed off ground surfaces inhibiting infiltration and increasing surface run off. Large scale under ground water extraction led to drying up of water reservoirs at the rate of 0.50-1.5 m/year. Eutrophication of streambeds consequential to increased inflow of city sewerage and industrial effluents was the obvious result. Major water impact in the Domesticated Agro-Ecosystem resulted from Green Revolution beginning with mid-1960s. There was 215.57% increase in area irrigated from ground water during 1967-68 to 1990-91 period. At some places water table fell by more than 8 m. Significant hydrological events of the Punjab Plain area of the Inter State Chandigarh Region, were the floods of 1988 and 1993. It may be pointed out that the hydrological spectrum of the region has been adversely effected by rapid land use/land cover changes.

5 illus, 2 tables, 36 ref

015222   Wani H;Mondal M E A (Geology Dep, Amarsingh College, Srinagar-190 008, Email: emondal2002@yahoo.co.in) : Provenance and tectonic setting signals of the neoproterozoic basins of the bastar craton: evidence from sandstone petrology and geochemistry. Proc Indian Natn Sci Acad 2007, 73(2), 81-90.

The lower parts of the Chattisgarh Basin and the Indravati Basin of Bastar craton start with the sandstone successions as the Chandarpur Group and the Tiratgarh Formation respectively. The sandstones of the Chandarpur Group of the Chattisgarh Supergroup show a broad similarity in composition with sandstones of the Tiratgarh Formation of Indravati Group. Sandstones of the Chandarpur Group display progressive change towards greater mineralogical maturity from base to top of the succession. On average, compositions of Chandarpur Group become mature in Upper Kansapathar Formation. The proportion of framework quartz increases upwards stratigraphically. The chemical data also show that SiO₂ increases and CaO, Na₂O, K₂0 decrease through time at the expense of less robust constituents. Provenance of sandstones of the Chandarpur Group and Tiratgarh Formation on QtFL diagram has been established as cratonic interior provenance while on QmFLt diagram, sandstones are considered to have been derived from cratonic interior and quartzose recycled provenance. The overall petrological and geochemical evidence indicate their source rocks were granites, gneisses and metasedimentary rocks, while mineralogical and geochemical maturity of sandstones suggests tectonic stability of the provenance and some contribution from pre-existing sedimentary rocks. Presence of multi-cycle quartz grains, chert and glauconite grains support the above conclusion.

7 illus, 3 tables, 52 ref

015221   Vaid B H;Gnanaseelan C;Salvekar P S (NO, Institute of Tropical Meteorology, Dr Homi Bhabha Road, Pune-411 008, Email: bhv@tropmet.res.in) : Observed twin gyres and their interannual variability in the equatorial Indian Ocean using Topex/Poseidon altimetry. Curr Sci 2008, 95(1), 30-5.

Recent numerical models have simulated the equatorial Indian Ocean twin gyres. However, there is no strong observational evidence for the existence of these gyres. Satellite technology and filter techniques are explored in this study to provide observational evidence for the existence of these gyres. The westward-propagating Rossby waves in the equatorial Indian Ocean, filtered from the Topex/Poseidon sea surface height anomalies (SSHA) showed the twin gyre structure which coincides with the model-simulated gyres. The present study further addresses the interannual variability of these gyres, especially during the Indian Ocean Dipole (IOD) years. The anomalous wind stress curl is found to drag the annual Rossby waves during the IOD years in the region 78°E-88°E. The downwelling favourable wind stress curl deepens the thermocline and increases SSHA and sea surface temperature.

7 illus, 18 ref

015220   Thakur S S;Tripathi K (NO, Wadia Institute of Himalayan Geology, 33 GMS Road, Dehra Dun-248 001, Email: satya_edu1974@yahoo.co.in) : Regional metamorphism in the Haimanta group of rocks, Sutlej river valley, NW Himalaya, India. Curr Sci 2008, 95(1), 104-9.

Pelitic rocks of the Haimanta Group exposed in the Sutlej river valley, NW Himalaya have undergone kyanite-grade regional metamorphism. The rocks show evidences of two phases of deformation (D₁ and D₂), which have led to the development of S₁ and S₂ schistosities respectively. Numerous granite veins fed by the lower Palaeozoic Kinnaur Kailash granite pluton have intruded the area parallel to the S₁ schistosity of the host rocks. Many of the granite veins are folded by D₂ deformation, and have intruded either before or during the early part of D₂ deformation. Pelitic schists in the area contain porphyroblasts of garnet, staurolite and kyanite. Elongated grains of kyanite and staurolite aligned parallel to S₁ schistosity show microfolding related to D₂ deformation, and are interpreted to have grown during the early part of D₂ deformation. Garnet porphyroblasts show reverse chemical zoning due to retrogression. Geothermobarometric calculations yield peak P-T conditions of 9.1 kbar and 625°C.

6 illus, 3 tables, 18 ref

015219   Sudarsana Raju G;Venkatrami Reddy Y;Gaghu Babu K (Geoinformatics Dep, Yogi Vemana University, Kadapa-516 003) : Hydrological aspects of Rajampet - a drought prone taluk, Kadapa district, Andhra Pradesh (India). J envir Sci Engng 2009, 51(2), 97-102.

Rajampet taluk is semi-arid and drought prone situated in Kadapa district in Rayalaseema, Andhra Pradesh, was selected to conduct groundwater investigations. The study area was investigated in terms of its geology, hydrogeology, geoelectrical, aquifer parameters and quality of water. The groundwater samples from the wells of Rajampet taluk were collected and the chemical analysis for various parameters has been carried out. The data pertaining to water quality has been systematically processed and the results are presented numerically and graphically. 54 YES were carried out throughout the taluk. Pump test has been carried out in selected bore wells in the study area.

3 illus, 5 tables, 12 ref

015218   Sharma R;Rameshwar Rao D (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001, Email: rajeshsharma@wihg.res.in) : Fluid inclusion studies of granitoid rocks from th central part of Askot crystallines, Kumaun Himalaya. Himalayan Geol 2008, 29(2), 137-45.

Deals with the fluid inclusion study of granite rocks from the central part of Askot crystallines. The fluid inclusion chronology and composition of these rocks are used to establish the nature of fluids during the evolution of granite. The studies suggested six types of inclusions, two types in early quartz and four types in late quartz. The early inclusions include liquid carbonic and aqueous-carbonic inclusions (type-I and type-II), with higher CO₂ density. The monophase liquid carbonic inclusions (type-III), and aqueous-carbonic inclusions (type-IV) in late quartz shared most of the evolutionary history: post-metamorphic and Himalayan tectonic. On the other hand, the vapour rich (type-V) and liquid rich (type-VI) biphase saline aqueous inclusions show flux of boiling hydrothermal fluid during post-peak metamorphic effects. Unlike most of the Himalayan crystallines wherein fluid composition with significant CO₂ remains consistent during their evolution, study presents the possibility of an early deep H₂O-CO₂ and hydrothermal fluid involvement during their evolution.

5 illus, 1 table, 36 ref

015217   Shandilya A K (Applied Geology Dep, Dr. Hari Singh Gaur Univ, Sagar, Madhya Pradesh, Email: akshandilya_u@rediffmail.com) : Natural gas leakages from bore wells in the Vindhyan supergroup, Sagar and Damoh districts, Madhya Pradesh (India). Himalayan Geol 2008, 29(2), 193.

^ssc1 illus, 1 table

015216   Rohtash Kumar;Sangode S J;Ghosh S K;Sinha S (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001, Email: rohtash@wihg.res.in) : Marine to fluvial transition and erosional hiatus in the paleogene sediments of NW Himalayan foreland basin, India. Himalayan Geol 2008, 29(2), 147-60.

A 260 m thick Paleogene sedimentary succession encompassing Subathu and Dagshai formations, shows variations in genetically linked lithofacies, detrital modes and rock magnetic parameters. The Subathu Formation comprising grey to dark grey splintery shales with minor inter-layered lenticular calcareous sandstone and Nummulites bearing limestone having typical ferrimagnetic assemblage reflects the shallow marine setup. It is followed by mudstone with calcareous concretion, trace fossils and mixed ferri- and anti-ferromagnetic mineralogy of 'passage beds' and is capped by interbedded greyish white medium- to coarse- grained sharp based sandstone (siliciclastic) and red to purple mudstone with profuse concretions. Subsequently this is overlain by sandstone - mudstone alternations of the Dagshai Formation representing the interfluve domain of the coastal plain set up. Two maximum flooding surfaces within the Subathu Formation and sequence boundary at the sharp based sandstone are recognised. The withdrawal of the Subathu sea and contemporary sea level changes are largely controlled by the Himalayan embryonic setup during middle Lutetian. The coarsening-up Dagshai fluvial succession suggests basin-ward facies migration with a significant change in basin morphology owing to the availability of large accommodation space. Variations in architectural elements, detrital modes and rock magnetic characteristics across the marine to fluvial transition establish the sequence boundary, which is contemporaneous with the accelerated Himalayan uplift coeval to India-Asia collision.

11 illus, 51 ref

015215   Regmi K R;Arita K (Central Dep of Geology, Tribhuvan Univ, Kathmandu, Nepal, Email: kamalregminp@yahoo.com) : Major and trace element geochemistry of augen gneisses from the higher Himalayan crystalline zone, main central thrust zone and lesser Himalayan dome in Tamakoshi-Likhu Khola area, east Nepal. Himalayan Geol 2008, 29(2), 95-108.

In the Tamakoshi-Likhu Khola area, east Nepal, granitic augen gneisses are exposed in the Higher Himalayan (HH) crystallines, footwall of the Main Central Thrust (MCT) and core of the Lesser Himalayan (LH) dome. Major and trace element geochemistry were investigated in these gneisses. Generally, major and trace element composition of the HH, MCT footwall and LH dome gneisses are broadly similar and these are distinguished from each other in their structural disposition. The high molar A/CNK values of these gneisses indicate that they are peraluminous, which is also supported by the siderophyllitic nature of Biotite. Besides, the major element compositions of the gneisses under consideration have very similar trends to that of peraluminous S-type granites as defined by Patino Douce (1999). Field occurrence, mineralogy and geochemistry i.e., high SiO₂, low CaO and MgO, high Rb, low Sr contents, low Nb/Th ratios, and peraluminous nature suggest that the protoliths of these gneisses must be S-type granites that are products of crustal melting. The granites are deformed and metamorphosed to different grades.

9 illus, 3 tables, 29 ref

015214   Ramesh C;Vivekanandan N;Surwade K B;Bapat A D;Govindan S;Mathew F T (Central Water and Power Researc Station, , Pune) : Extreme value analysis of rainfall in Mumbai region to AID estimation of severe flood. ISH J Hydraul Engng 2008, 14(2), 102-17.

Assessment of risk from natural catastrophic events is essential for engineering and land use planning. In our country among many hazards, floods assume importance because of their recurring nature, and hence managing of floods is essential to prevent the losses to property and life. Though forecasts are issued for monsoon rains, largeªscale variations in severe storms do occur. Moreover, catchment response in producing high magnitude floods is also not accurately predicted. In estimating severe flood, for ungauged basins, it is essential to estimate extreme rainfall (say 50-year, 100-year... return periods) of desired duration (hourly or daily) and estimate the resulting flood from it. This paper presents a methodology adopted in Extreme Value Analysis (EVA) of rainfall for Mumbai region using maximum daily rainfall. Further, the maximum I day rainfall obtained for the 100 year return period is distributed over 24 hours of I-hour duration adopting an appropriate storm (6 hourly) for the region, that could be used in estimating severe flood for the case under study. The probability distribution adopted in EVA is subjected to D-index Goodness of fit test. The Log Pearson Type III distribution is found to be best suited for EVA for the study region.

7 illus, 6 tables, 10 ref

015213   Pradipkumar Singh K (Geography Dep, Manipur Univ, Imphal, Manipur) : Siltation in Loktak lake: a geographic study. Trans Inst Indian Geogr 2008, 30(1), 25-32.

Land and Water are the most important resource of life in any environmental condition. By taking the advantage of achievement people have started exploiting the natural resources at an alarming rate. Loktak, the fresh water lake, is now under threat due to several integrated factors mainly caused by anthropogenic pressure. Large scale and rapid degradation of forests in the upper catchment area has led to the serious problems of siltation and reduction in water holding capacity of the lake. These problems are further enhanced by the construction of Ithai Dam across the Imphal river that has changed hydrological regime of the lake.

2 illus, 4 tables, 6 ref

015212   Patel N R;Shete D T (NO, Water Resources Engineering and Management Institute, Faculty of techn, Samiata-391 410) : Probability distribution analysis of consecutive days rainfall data for sabarkantha district of north Gujarat region, India. ISH J Hydraul Engng 2008, 14(3), 43-55.

Various probability distributions and transformations can be applied to estimate one day and two to seven consecutive days rainfall of various return periods. In the study 16 different types of continuous probability distributions were tested using Akaike Information Criterion (AIC) and Bayesian Information Criterion (BIC) for goodness of fit of an estimated statistical model for Sabarkantha district of Gujarat, India. For the study daily rainfall data from 42 raingauge stations for 45 years.( 1961-2005) are obtained from State Water Data Centre, Gandhinagar, Gujarat. Inverse Gaussian distribution is best fitted to one day and consecutive 2,3,4,5,6 and 7 days rainfall dataset by both the AIC and mc criterions.

7 illus, 5 tables, 4 ref

015211   Naik S S;Divakar Naidu P (NO, National Institute of Oceanography, Goa-403 004, Email: divakar@nio.org) : Possible factors that control calcite dissolution in the western tropical Indian Ocean. Curr Sci 2008, 95(1), 22-3.

1 illus, 1 table, 12 ref

015210   Mujumdar P P;Ghosh S (Civil Engineering Dep, Indian Instituter fo Science, Bangalore-560 012) : Climate change impact on hydrology and water resources. ISH J Hydraul Engng 2008, 14(3), 1-17.

Presents an overview of the methodologies developed for assessing hydrologic impacts of climate change with an emphasis on statistical techniques for regional impact assessment and modelling of uncertainty, resulting from the use of multiple climate models. The methodologies are demonstrated with the case study of Orissa meteorological subdivision and Mahanadi river basin which shows a possible decreasing trend in rainfall and monsoon streamflow of the region in future.

8 illus, 30 ref

015209   Malik J N;Nakata T;Philip G;Suresh N;Virdi N S (Civil Engineering Dep, Indian Institute of Technology-Kanpur, Kanpur-208 016, Email: javed@iitk.ac.in) : Active fault and paleoseismic investigation: evidence of a historic earthquake along Chandigarh fault in the frontal Himalayan zone, NW India. Himalayan Geol 2008, 29(2), 109-17.

The Himalaya is seismically one of the most active terranes in the world. Seismic and related hazards affect not only the Himalaya but also the adjacent alluvial plains. Convergence of Indian and Eurasian plates and ongoing activity along three major faults viz. MCT, MBT and HFT often generate large and destructive earthquakes. We have attempted to demarcate active faults using high resolution CORONA photographs and a DEM of the area adjacent to the Himalayan Frontal Thrust (HFT)near Chandigarh. The studies have been complemented by trenching along the HFT and by OSL dating of sediments in the trench. The HFT has repeatedly ruptured in the past as is evident from fault scarps with heights varying from 15-38 m. The OSL dates further suggest the occurrence of a major earthquake around 1300-1400 A.D. and corroborate the report of such an event from the Himalayan Front about 600 years back.

6 illus, 1 table, 45 ref

015208   Kotlia B S;Phartiyal B;Kosaka T;Bohra A (Geology Dep, Kumaun Univ, Nainital-263 002, Email: bahadur.kotlia@gmail.com) : Magnetostratigraphy and lithology of Miocene-Pliocene Siwalik deposits between Tanakpur and Sukhidang, southeastern Uttarakhand Himalaya, India. Himalayan Geol 2008, 29(2), 127-36.

Detailed magnetostratigraphy and lithostratigraphy of a 3,000 m thick Siwalik sequence exposed between Tanakpur and Sukhidang in the eastern Uttarakhand Himalaya are carried out. Lithologically, the section is divided into five units, each with independent characteristics. Three faults, namely South Bastia Fault, North Bastia Fault and Sukhidang Fault are documented. 450 samples from 90 sites were analyzed for palaeomagnetism and the results are correlated with the Geomagnetic Polarity Time Scale (GPTS) suggesting an age ranging from 12.5 Ma (base of Chron 5 An) to 4.0 Ma (base of Chron 2 Ar) with an average sediment accumulation rate of ~32 cm/1000 yr. The magnetic data confirm 35 magnetic polarity zones with 18 normal and 17 reversals.

8 illus, 1 table, 45 ref

015207   Karmakar S;Kowafr M K;Guhathakurta P (Computer Applictions Dep, Bhilai Institute of Technology, Bhilai House, Durg-491 001, Email: karmakar_sanjeev@yahoo.com) : Evolving and evaluation of 3LP FFBP deterministic ANN model for district level long range monsoon rainfall prediction. J envir Sci Engng 2009, 51(2), 137-44.

In order to develop a forecasting model for monsoon rainfall over the districts of Chhattisgarh, 3LP (Three Layer Perception) FFBP (Feed Forward Back Propagation) Deterministic ANN models have been proposed. In the proposed model, eleven neurons in input layer, one hidden layer with eleven neurons, a single neuron in output layer, 132 trainable weights in three layers, transfer function sigmoid 1/(1+e^-δx+η) with slope a=l, threshold c=0 have been used to evolve networks. Training of the network is continued till the mean square error becomes less than a pre-assigned value ranging from 0.0005 to 0.001. Data for the years 1945-2006 have been used, out of which the data of first 51 years, i.e., (-δ+η1945-1995, are used for training the network and data for the remaining period, i.e. during the period 1996-2006 are used independently for validation. In the study, it has been observed that the mean absolute deviation (% of mean) values for the independent period (1996-2006) are less than and half of the standard deviation (% of mean) for all the districts. The performances of these 3LP FFBP Deterministic ANN models have been found to be extremely good and better evaluated over statistical trend models also. The models developed and their evaluations have been presented.

7 illus, 2 tables, 31 ref

015206   Jaisi D P;Dhital M R;Panthee S (Geology Dep, Tri-Chandra Campus, Tribhuvan Univ, Ghantaghar, Kathmandu, Nepal, Email: deb.jaisi@yale.edu) : Geology of the Kusma-Behadi fold belt area, Lesser Himalaya, central west Nepal. Himalayan Geol 2008, 29(2), 119-26.

The Kusma-Behadi area of the Lesser Himalaya in central west Nepal comprises Late Precambrian-Early Paleozoic low - to medium-grade meta-sedimentary rocks of the Nawakot Complex, which is divided into the Kuncha Formation, Naudanda Quartzite, Nayagaun Phyllite, Nourpul Formation, Dhading Dolomite and Benighat Slate from bottom to top, respectively. The Kuncha Formation consists of 'gritty' phyllite with micaceous quartzite and quartz conglomerate intercalations with a few beds of amphibolite. The Naudanada Quartzite comprises rippled, cross- and graded- bedded green to white quartzite with phyllite intercalation. Lineated phyllite with sandstone intercalations is the predominant lithology of the Nayagaun Formation. The Nourpul Formation consists of strongly rippled white quartzite and intercalated green phyllite in the lower part, green to purple slate with limestone and sandstone in the middle, and interbedded green phyllite and pink siliceous dolomite in the upper part. The Dhading Dolomite is unique with dominant stromatolitic and intraformational dolomite. The Benighat Slate contains highly cleaved carbonaceous and banded slate. The area consists of many south-vergent mesoscopic and small-scale folds possibly related to movement of the regional faults. The Phalebas Thrust separates Balewa-Shakarpokhari Synformal Anticline and Bhoksing Fold Belt in the study area. The doubly plunging Balewa-Shakarpokhari Synformal Anticline shows inverted stratigraphy and contains several small scale folds of higher generations. The tightly to isoclinally folded Bhoksing Fold Belt consists of asymmetrical, gently dipping folds with overturned shorter limb. Many asymmetrical minor folds in the study area show their axial plane and fold axes parallel to those of major folds, and their vergence pointing to the core of anticlines suggesting the southward direction of tectonic transport.

7 illus, 30 ref

015205   Il-Kon K;Ahmed R (NO, Silla Univ, Republic of Korea, Busan-617 736) : Probabilistic estimates of rainfall extremes in the Republic of Korea during the summer season. Trans Inst Indian Geogr 2008, 30(1), 1-14.

The summer season (June - September) in the Republic of Korea (South Korea) is warm and rainy. More than 60 percent of the total annual rainfall comes during the summer season. Because of high temperature and rainfall, summer is the main growing season in most of the country. Summer rainfall in the country varies from place to place and from year to year. Both high and low rainfall amounts have tremendous effects on agriculture and hydrology in the country. High rainfall causes soil erosion, flooding, and landslide. On the other hand, low rainfall amount causes drought; water shortage for industry, urban and domestic water uses. Study presents the geographic distribution of the probabilistic amounts rainfall of various magnitudes and frequencies in South Korea, for each month of summer season (June - September) and for the summer season as a whole. Probabilistic amounts of both below-normal rainfall and above-normal rainfall have been determined for two time scales: (a) in 1 year out of 4 years, which is a relatively more frequent event; and (b) in 1 year out of 10 years, which is a relatively extreme event. Results of the study may serve as an inventory of rainwater resources in the country during the summer season which will be useful to the agricultural planners, irrigation engineers, hydrologists, transportation engineers and local and regional planners for the proper utilization and management of the water resources and hazard potential.

6 illus, 26 ref

015204   Dongre N L (NO, , ) : Rational derivation of river-bed profile. Trans Inst Indian Geogr 2008, 30(1), 15-23.

River Morphologists have been faced with the dilemma for many years. On the one hand, its accumulated experience is sometimes inadequate for reliable prediction of river behavior while, on the other hand there has been little attempt at systematic quantitative evaluations to 'discover identity in difference' - all the above referring particularly to the form of river-channels, in plan and profile. Purpose of the paper is to review certain principles which afford a rational derivation of the profile of river-beds and to test the results on Denwa River tributary ofTawa River of Central India.

7 illus, 16 ref

015203   Chaudhuri S;Wakhare A;Kamble A (NO, Jogmaya Devi College, Kolkata-700 033, Email: suvamita@hotmail.com) : Effect of construction of protection wall on beach - dune morphology of Shrivardhan bay mouth spit, Konkan coast, Maharashtra. Trans Inst Indian Geogr 2008, 30(1), 53-67.

Sea walls are barrier to wave impact and can alter swash and backwash velocities, modify the beach slope and have significant impact on sediment budget. The morphological changes that have been brought about in the beach-dune morphology of the Shrivardhan bay mouth spit by the construction of the protection wall have been monitored and documented in Ms article. The direct or indirect effects of the wall on the position of the high tide line of the beach have also been assessed. Periodic theodolite surveys and photography were carried out to detect short-term changes from 1998 to 2002. Wave refraction diagram was prepared to detect the relation between wave refraction pattern and the zones of erosion. Field observations revealed that the wall had a definite influence on beach elevation, development of runnel and low tide bar. Observation redistribution of material over the beach, of contemporary course of events show that, the protected portion of the beach first starts to gain elevation with accelerated sand accumulation at the base of the wall. If there is subsequent seaward shift of the high tide line the zone comes under the purview of wind deposition and the beach assumes an accretionary nature. The unprotected southern part of the beach, downdrift of the wall experienced active erosion, as a major proportion of the wave energy was expended where the wall terminates.

6 illus, 3 ref

015202   Chattopadhyay G P (Geography Dep, Visva-Bharti, Santiniketan-731 235, Email: cguruprasad@rediffmail.com) : Recent retreats of glaciers on the southeast-facing slopes of the Kanchenjunga summit complex in the Sikkim Himalaya. Himalayan Geol 2008, 29(2), 171-6.

An assessment of the Quaternary history of high altitude environments around the southeast-facing slopes of the Kanchenjunga summit complex in the Sikkim Himalaya has been made on the basis of analyses of records obtained through extensive field surveys by the author in 1995, 1997 and 2005. Particular attention has been paid to the conditions of two main glaciers in this part, namely Onglaktang Glacier and Rathong Glacier, and around these two glaciers three sets of morainic loops (corresponding Stage I, Stage II and Stage III), each comprising lateral and terminal moraines, extending down the valley from the active zone of the glaciers, have been identified and interpreted of their geomorphologic significance. Recent retreats of Onglaktang and Rathong glaciers (from Stage III advance maximum) have been found to vary between 1km and 1.2km. Approximate volumes of these glaciers have been calculated considering their existing length, width and thickness and a reconstruction of the maximum volume attained by them (during the Stage III advance), calculated upon the extent of fresh morainic profiles, has also been attempted. It has been found that Onglaktang and Rathong glaciers have been reduced to 30.77% and 17.09% respectively as a result of recent retreats. Various forms of recent human interference have been attributed to this increasingly rapid rate of glacier retreats, and it has been apprehended that if this condition continues to prevail, most of the rivers issued from this part, will suffer from hydrological misbalance through the seasons round the year inflicting detrimental effect on the physical environment around North Bengal.

4 illus, 1 table, 15 ref

015201   Chakraborty P K;Lahiri A K (Central Geophysics Div, Geological Survey of India, 27, J.L. Nehru Road, Kolkata-700 016) : Microgravity monitoring in Sikkim-Darjeeling Himalaya - an area of potential seismic hazard. Himalayan Geol 2008, 29(2), 161-9.

The Sikkim-Darjeeling area is seismically active and has experienced a number of earthquakes (M>5) in the recent past. Microgravity measurements were conducted from May, 2001 to January, 2005 in campaign mode at about six month's interval to monitor temporal gravity changes in this potential seismic hazard zone. Gravity observations were carried out using a CG-3M microgravimeter (1 microGal resolution) along three profiles: one N-S across the Main Boundary Thrust (MBT) and the other two, NE-SW and NW-SE between the MBT and Main Central Thrusts (MCT) covering 31 gravity stations. Significant temporal gravity changes in the range of 30 to 290 microGal were observed and based on these temporal gravity changes two anomalous sections were identified. The first is along a N-S profile between Ranipul and Gangtok, about 10 km horizontal stretch, with a maximum change of -174 microGal at Gangtok and the second between Peshok and Takdah, about 15 km horizontal stretch, with a maximum change of -290 microGal at Takdah along NE - SW profile. Both the sections are located in seismically active area between MBT and MCT and closer to MCT. It is postulated that the significant gravity decrease with time observed in the area is possibly caused by uplift and the related redistribution/deformation of geological sequences above the gentle dipping basement under tectonic movements in this part of Himalaya. A possible relation between temporal gravity change and recent seismicity is discussed. The gravity decrease of the order of -174 microGal (relative to the 1st campaign) observed at Gangtok in 7th campaign during January, 2005 before the occurrence of earthquake (Mw 5.7) on Feb. 14, 2006 about 70 km NW of Gangtok may be interpreted as some kind of precursor to this event.

5 illus, 30 ref

015200   Bhagavathi Perumal S;Thamarai P (Civil Engineering Dep, National College of Engineering, Tirunelveli-627 151, Email: sbperumal@rediffmail.com) : Ground water quality after tsunami in coastal area of Kanyakumari, South Tamilnadu, India. Int J appl envir Sci 2008, 3(1), 37-55.

Hydrochemistry of groundwater in Coastal Area of Kanyakumari to Colachal coastal belt after Tsunami, South Tamil Nadu, India was used to assess the quality of groundwater for determining its suitability for drinking and agricultural purposes. Physical and chemical parameters of groundwater such as electrical conductivity, pH, total dissolved solids (TDS), Na⁺, K⁺, Ca²⁺, Mg²⁺, Cl^-HCO₃-, CO₃^2-, SO₄^2-, NO^-₃, F^-, B^- and SiO₂ were determined. Concentrations of the chemical constituents in groundwater vary spatially and temporarily. Interpretation of analytical data shows that mixed Ca-Mg-Cl, Ca-Cl and Na-Cl are the dominant hydro chemical faces in the study area. Alkali earths (Ca²⁺, Mg²⁺) and strong acids (Cl-, SO₄²) are slightly dominating over alkalis (Na⁺, K⁺) and weak acids (HCO₃^-, CO₃^2-). The abundance of the major ions is as follows: Na⁺>Ca²⁺>Mg²⁺>K⁺ =Cl>HCO₃>SO₄²<62 >NO₃. Groundwater in the area is generally very good, pleasant, fresh to brackish, average to very low saline and low alkaline in nature and fit both for agriculture and drinking purposes. Permissible average Total Hardness and TDS in all places of the study area identify the suitability of groundwater for drinking and irrigation. In some areas due to high Total Hardness and TDS identified in ground water such areas require special care to provide adequate drainage and introduce alternative salt tolerance cropping. Based on the TDS value, the ground water in these areas is of bicarbonate/calcium chloride/sodium chloride type. Fluoride and boron are within the permissible limits for human consumption and crops as per the international standards. Nitrate concentration is slightly high in some areas. In the study area less ground water extraction keeps the water table high. The elevated topography, more rainfall and limited ground water extraction, keeps the Kanyakumari coastal belt free from sea water intrusion. The surface water resources have been fully utilized. The surface flow is more during monsoon periods. Surface water and rain water are widely used for irrigations. Surface water irrigation constitutes nearly 94% of major source of irrigation. Of the total net area irrigated only 6% is under well irrigation and hence there is no over extraction of ground water in the area. Quality of water is generally good through out the district except some places in the study area like Keelamanagudi, Thengampudur and Colachal and some pockets along the coastal belt. Comparing the results of water parameters before and after Tsunami there is not much change in the quality.

7 illus, 11 tables, 15 ref

015199   Batheja K;Sinha A K;Seth G (Geology Dep, University of Rajasthan, Jaipur-302 004) : Water treatment for removal of nitrate. Asian J expl Sci 2009, 23(1), 61-6.

Groundwater studies in arid zones of Churu block and adjacent villages exhibit high nitrate concentrations which make the groundwater unsuitable for drinking. Though there are many nitrate remediation methods/products in market, these may not be feasible for use at rural level. This paper describes a preliminary investigation on nitrate remediation abilities of active neutral alumina, activated charcoal, agar, yellow mustard and bentonite in singular or combined form. With some limitations these remedial measures can prove to be helpful in reduction of nitrate concentration in groundwater of the study area to appreciable extents.

3 illus, 5 tables, 5 ref

015198   Azmi R I;Joshi D;Tiwari B N;Joshi M N; Srivastava S S (NO, Wadia Institute of Himalayan Geology, Dehra Dun-248 001) : Synoptic view on the current discordant geo- and biochronological ages of the Vindhyan supergroup, central India. Himalayan Geol 2008, 29(2), 177-91.

Presents a synoptic view on current discordant views on the age of the Vindhyan Supergroup (VSG), arising from the recent geo- and biochronological data sets. Against exceptionally long duration of ~1200 million years (~1800-600 Ma) from late Paleoproterozoic to late Neoproterozoic age based on geochronology, diverse paleontological evidences (metazoan traces, small shelly fossils, fossil embryos, calcareous skeletal algae, sponge spicules, acanthomorphic acritarchs, scolecodont-like structures and metaphytes) suggest a much shorter duration of Vendian -Early Cambrian (~650-520 Ma) for deposition of the VSG. It is demonstrated that ~1800 Ma (late Paleoproterozoic) initiation of the Vindhyan sedimentation is not in conformity with the regional geology, whereas the younger age for the VSG is consistent with the regional geology and is also supported by a basal Vindhyan glaciation of correlatable Marinoan (Vendian) age ("Snowball Earth"). It is believed that the wide age disparity in the VSG stands sorted out by adhering to the regional geological perspective of |he Vinuhyan Basin.

6 illus, 114 ref

014170   Zarei Sahamieh R;Ahmadi Khalaji A (Faculty of Science, Lorestan Univ, Khorram Abad, Iran, Email: zareisah@yahoo.com ) : Geochemical characteristics of the granitoid complex of boroujerd, sanandaj-sirjan zone, western Iran. Indian Mineralogist 2008, 42(1), 1-19.

The granitoid complex of Boroujerd belongs to the Sanandaj-Sirjan Zone (SSZ) in the western Iran. It is elongated and parallel to the prevailing schistosity in the metamorphic rocks trending NW-SE and consists of quartz diorites, granodiorites, monzogranites and acidic dykes (aplites and pegmatites). This complex is of sub-alkaline affinity and belong to the high-k calc-alkaline series, metaluminous to weakly peraluminous and display features typical of I-type granites. Trace and rare earth element distribution patterns for the Boroujerd granitoid rocks indicate a distinctive depletion with respect to primitive mantle in Nb, Eu, Sr, Ba, P and Ti relative to other trace elements and a greater enrichment in LILE compared to HFSE. These geochemical characteristics suggest that these rocks are derived from a crustal source. The granitoid complex of Boroujerd has geochemical characteristics typical of arc intrusives and plot as volcanic arc granites on various discriminant diagrams. This granitoid and is typical representatives of a volcanic arc environment, spatially related to an active continental margin. Probably, it is the result of the subduction of Neo- Tethyan oceanic crust below the Iranian microcontinent. All available data are compatible with the idea that these rocks represent the products of convergent margin processes during Mesozoic.

10 illus, 1 table, 35 ref

014169   Velmurugan A;Swarnam T P;Praveen Kumar; Ravisankar N (NO, Indian Institute of Remote Sensing, Dehradun-248 001) : Soil erosion assessment using revised Morgan, Morgan finney model for prioritization of Dhanikhari watershed in south Andaman. Indian J Soil Conserv 2008, 36(3), 179-87.

Natural resources of Andaman Islands are constrained due to anthropogenic interference in the form of farming on slopes and deforestation which causes accelerated erosion. Assessment and mapping of erosion prone areas facilitate soil conservation and watershed management. This study used revised Morgan, Morgan and Finney model (RMMF) to assess spatial soil erosion risk at field plot and watershed scale with the aid of remote sensing and GIS. The model was calibrated using field plot observations and the model predicted soil loss was close to the observed value (R² = 0.9). The results indicated that the annual average soil loss from Dhanikhari watershed was 25.29 t/ha and total soil loss was 27,142 tonnes. The model predicted relatively higher soil loss under agriculture especially under plantation crops in the higher slopes. The estimated annual soil loss rates were classified into six severity classes and the majority of the watershed falls in very low priority category followed by low, very high and high.

3 illus, 7 tables, 21 ref

014168   Srivastava R C (NO, Central Agricultural Research Institute, Portblair-744 101) : Water resource development in Andaman & Nicobar Islands - a futuristic vision. Indian J Soil Conserv 2008, 36(3), 165-7.

Andaman and Nicobar islands are eastern most fringe of our country consisting 572 islands with an area of 8429 sq km having only 6% area under cultivation. Although the islands region receives an average annual rainfall of 3070 mm spread from May to November, agriculture is mostly rainfed and people even face problem of drinking water during dry period. Ground water availability is almost zero with no well defined aquifer except some perched aquifers, leaving rain water management as the only viable solution for providing water for irrigation as well as domestic water supply. An attempt has been made to devise rain water management pratices in different topographical situations to provide water during the dry season. This article describes the potential of such management.

1 illus

014167   Srinivasa Reddy G V;Bhakar S R;Purohit R C (NO, College of Technology and Engineering, MPUAT, Udaipur) : Drought evaluation and climatic variability assessment in Bangalore region, Karnataka. Indian J Soil Conserv 2008, 36(1), 6-10.

Agricultural drought occurs when soil moisture and rainfall are inadequate during crop growth season to support a healthy crop. The present study has been carried out for accounting agricultural drought and climatic shift based on climatic water balance method on seasonal basis in Bangalore region. The study revealed that the weekly water deficit during kharif season varied from 1.18 to 13.04 mm and surplus ranged from 1.03 to 48.83 mm accounting for total surplus of 260.89 mm. The surplus water during kharif season gives scope for rainwater harvesting, conservation and recycling during the stress period. Drought years were identified and their intensities were assessed by the help of departure of annual aridity indices. During the study period, Bangalore experienced 5 moderate (20 %), 4 large (16 %) and 4 severe (16 %) drought years within a period of 25 years. Climate varied from moist sub-humid to semi-arid whereas, dry sub-humid climate was found to be prominent one based on moisture index (Im) procedure.

1 illus, 3 tables, 11 ref

014166   Srikantappa C;Malathi M N (Studies in Geology Dep, Mysore Univ, Manasagangothri, Mysore-570 006, Email: srikantappa@googemail.com) : Solid inclusions of magmatic halite and co₂-H₂O inclusions in closepet granite from Ramanagaram, Dharwar craton, India. Indian Mineralogist 2008, 42(1), 84-98.

Presence of halite and nahcolite bearing, primary fluid inclusions in quartz grains from the Closepet granite in the Archaean Dharwar craton represent the early magmatic fluids in granites. Coeval with these saline inclusions, presence of low XCO₂ type CO₂-H₂O inclusions occur. The trail bound CO₂-H₂O inclusions show stretching with irregular outlines, 'U' and double shapes showing evidences of leakage of H₂O during crack-healing process, suggesting post-entrapment modifications. There is considerable increase in the volume proportion of CO, including their density in chronologically late CO₂-H₂O inclusions. Along late fractures (GSI-1I) which crosscut the early CO₂-H₂O trial (GSI-I), presence of CO₂ rich inclusions are recorded. Negative crystal shaped, isolated to trail bound, monophase CO₂ inclusions are abundant in the late quartz veins in Closepet granite. There is absence of CO₂-H₂O and aqueous inclusions in these quartz veins indicating the predominance of carbonic fluids during late magmatic stage in Closepet granite.

16 illus, 23 ref

014165   Shahinfar H (Geology Dep, Azad Univ of Tabriz, Iran, Email: shahinfarh@yahoo.com) : Improvement in characterization of crosta technique for porphyry copper alteration mapping using TM data in Varzagan, Azarbaijan, Iran. Indian Mineralogist 2008, 42(1), 44-52.

The copper mineralization in Varzegan and it's potentially ore bearing stock in Kighal-Syahkalan is situated in NW of Iran. The study area is the southern extension of Sungun porphyry copper deposit, confined to Himalayan Alp metallogenic belt. This zone is also related to NW-SE trending Cenozoic magmatic belt of Iran. Magmatic activities in Varzegan have exposed in the form of volcanic, subvolcanic rocks, igneous intrusive stocks and related alteration zones. This zone with 30 km width and great potential for Cu-mineralization is trending E-W at the central part of region. Remote sensing technique is applied in the area with the aim of detecting alteration zones, using Landsat-5TM data. In order to identify the rock units in the area, the color composite image are obtained by employing the optimized indices factor (OIF). The results reveal that image (7,4,1) (R,G,B) has maximum OIF, which are used to delineate between lithological units. Application of Crosta technique with two bands combinations 1,4,5,7 for clay and 1,3,4,5 for Fe-oxide, successfully attempted in detecting alteration zones related to mineralization. Using advantage of Crosta method, the combined and integrated image for Fe-oxide and clay alterations is prepared. An attempt is also made to differentiate the Fe-oxide and clay alteration zones with that of vegetations based on their reflectance and absorbance features, but basic intricate is observed in interpretation of composite image due to vegetation canopy, which produced false enhanced alteration halos in N-NW part of the area. To succeed the nebulous problem of image caused by vegetation coverage, the method developed by rejecting effects of 4th band from band combinations. The resulting image was improved and alterations zone discriminated from noises. The significant achievement of method displayed effectively as reliable guide for enhancing and detecting alteration zones in exploration for Cu-mineralization in NW metalogenic provinces of Iran.

3 illus, 5 tables, 17 ref

014164   Sethi R R;Kumar A;Sharma S P;Singadhupe R B (NO, Water Technology Centre for Eastern Region (ICAR), Bhubaneshwar, Orissa) : Water rsource assessment in Munijhara watershed of Orissa. Indian J Soil Conserv 2008, 36(3), 158-64.

A study was carried out to assess surface and groundwater resource potential, groundwater development status, water resources availability and demand in Munjihara waterhed of Orissa (India). The annual potential of 1719.55 ha-m includes both surface flow and runoff whereas groundwater potential was estimated to be 940.56 ha-m for the watershed. The annual water requirement was 1656,43 ha-m, which include crop water requirement of 1633.84 ha-m and domestic water demand of 22.63 ha-m during the period of 2006-2007. It was estimated that, out of approximately 884 ha-m of utilizable ground water resource in the watershed, about 700 ha-m is being withdrawn annually and there is a scope for exploiting a balance amount of 184 ha-m. Among the dominant crops, paddy accounted for 88% of crop evapotranspiration demand (ET_o) followed by vegetable crops with 6.28% of crop ET_o during the kharif season. In rabi season total crop evaporative demand was 1117 ha-m and pulse crop accounted for 96% followed by vegetables (2.7%) and oil seed (0.41%). Potential and demand scenario of the study area indicated that there was no water scarcity till 2006-2007 and it may continue till 2011-12 provided demand is fulfilled through groundwater during non-monsoon season. But the study also showed that 27% villages in the watershed were under grey zone where groundwater development is around 65-85% of the utilizabie resources and few villages have already been categorized as over-exploited stage. The above findings point towards the fact that, there' is need of scientific and rational conservation and utilization of surplus available water which is possible through interventions like design of suitable groundwater recharge structures that would commensurate the rate of draft and can bridge the gap between water availability and requirement.

1 illus, 6 tables, 23 ref

014163   Satyanarayanan M;Subba Rao D V;Nirmal Charan S;Anbarasu K;Karthikeyan A;Narsing Rao S;Dasaram B;Sawant S S;Balaram V (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007, Email: msnarayanan@ngri.res.in) : Petrological and geochemical characteristics of dunites and associated granulites of Salem and Nagaramalai areas in Tamilnadu, Southern India. Indian Mineralogist 2008, 42(1), 33-43.

The ultrabasic intrusives located in the gneiss-charnockite terrain in Tamilnadu are known to host industrial minerals such as olivine, asbestos and magnesite. They are confined to the intersection of two deep-seated lineaments, which dissect the Archaean high-grade gneiss-granulite terrain. In the present work, the dunites and the two pyroxene basic granulites and plagioclase bearing amphibolites from Nagaramalai areas are investigated. Fine disseminations of chromite and magnetite grains are conspicuous in these rocks with minor amounts of antigorite, chrysotile and lizardite serpentines. MgO in least altered dunites varies from 47.6 to 48.8% and 15.9 to 18.6 wt% in the serpentinized variety of dunites. Cr (1300 to 1826 ppm) and Ni (684 to 2191 ppm) contents are also high in these rocks. The marked abundance of alkali elements and incompatible elements in the serpentinized dunites is suggestive of a metasomatic introduction of these elements and are related to fluid-phase metasomatic processes. REE patterns of these rocks are similar irrespective of their MgO contents and show slight LREE enrichment, flat to depleted HREE and absence of Eu anomalies. The REE geochemistry of the least altered dunites indicates that they represent the mantle residue. Low PGE abundances are observed in the serpentinized dunites of Salem and basic granulites of the Nagaramalai areas. The basic granulites and amphibolites show slightly fractionated mantle normalized PGE patterns than that of the dunites which show flat/unfractionated PGE patterns. Major, trace and rare earth element geochemistry of dunites and the associated mafic magmatic rocks indicate their derivation from different degrees of partial melting of the mantle peridotite source.

6 illus, 1 table, 11 ref

014162   Ravender Singh;Kundu D K (NO, Water Technology Centre for Eastern Region Chandrasekharpur, Bhubaneswar-751 023) : Erodibility of major soil sub-groups of eastern region of India. Indian J Soil Conserv 2008, 36(3), 172-8.

Erosion index (EI) was determined for surface as well as subsurface layers of twenty six soil subgroups of eastern India. Soil erodibility was related to various physicochemical properties of the soils. In 0-15 cm layers, the highest erosion index 45.86 was observed in Typic Ustipsamment followed by Vertic Ustochrept 41.62, Aerie Haplaquept 39.16 and the lowest 2.99 in Rhodic Paleustalf. In 15-30 cm soil depth it varied from 36.89 in Aerie Fluvaquent to 7.26 in Typic Paleustalf. In the 30-150 cm layer, it varied from 40.85 in Aerie Fluvaquent to 8.29 in Ultic Paleustalf. Significantly higher value of EI was observed for 0-15 cm soil depth and no significant difference in EI was observed between 15-30 and 30-150 cm soil layers. In general erosion index decreased with soil depth. A highly significant and negative relationship of erosion index with clay, silt + clay, maximum water holding capacity and highly significant, and positive relationship with sand and dispersion ratio were observed. As the dispersion ratio increased, erosion index increased indicating susceptibility of these soils to water erosion. Based on the credibility characteristics of the major sub-groups of eastern region, it is suggested that all dominating soil subgroups of eastern region need some kind of soil and water conservation measures.

5 tables, 20 ref

014161   Prabhakar B C;Shareef M;Gireesh R V;Rashmi B N (Geology Dep, Bangalore Univ, Jnanbharathi, Bangalore-560 056) : Fluid inclusion study and hydrothermal source characterization of Thinthini copper sulfide deposit, eastern Dharwar craton. Indian Mineralogist 2008, 42(1), 20-32.

Fault-confined diabase intrusive occuring near Thinthini hosts basemetal sulfide mineralisation. This diabase and a narrow zone of adjacent granite have suffered pre, syn and post ore deformation resulting in intense fracturing, brecciation and mylonitization with conspicuous wall rock alteration (sericitisation, epidotization, chloritization and silicification). These structural features have served as pathways and sites for hydrothermally derived ore deposition. The cavity filling veins with disseminated sulfides (pyrite, chalcopyrite, bornite, pyrrhotite, cobaltite) and subordinate oxide (haematite) minerals have been formed in more than one stage of hydrothermal fluid ascent. Quartz and calcite are the chief vein minerals with occasional fluorite. The above three vein minerals have been sampled for fluid inclusion studies and microthermometry. Monophase (carbonic), biphase (H₂O-NaCl, H₂O-CO₂) and polyphase (H₂O-NaCl) primary inclusions of at least two generations have been studied and the P-T-X characterized. The first generation inclusions are predominantly biphase (H₂O-CO₂) with moderate to high salinity (15-31 wt% of NaCl eqvi.) and higher Th (200-380 °C) indicating their entrapment at boiling conditions at about 1 to 1.5 km depth and 284 to 403 bars pressure. These high saline hydrothermal solutions are thought to be responsible for first stage of sulfide mineralisation. The second generation inclusions are primary mainly aqueous, poor in carbonic oxides, moderate to poor salinity (0 to 15 wt% of NaCl eqvi.) and low Th (140-260 °C). These conditions indicate that they (inclusions) are entrapped during waning stages of hydrothermal fluid ascent from a cooling system of (diabase) magma and the exsolved solutions. These late stage ore bearing solutions produced feeble, but pervasive mineralisation in the diabase and adjacent cataclasite. Field setting, ore textures and fluid inclusion characteristics strongly favor magmatically derived hydrothermal source for ore deposition within an active tectonic regime.

5 illus, 31 ref

014160   Pandey S;Manoj Kumar;Mahanti N C (NO, Birla Institute of Technology, Mesra, Ranchi-835 215) : Evaluating interrelationship of meteorological parameters using regression model: a case study from Ranchi, Jharkhand, India.. Indian J Soil Conserv 2008, 36(3), 136-43.

Meteorological parameters are important variables, which influence the microclimate of a region. In the present study Various climatic parameters i.e., rainfall, relative humidity, soil temperature, wind velocity, wind direction, dry bulb temperature, wet bulb temperature, maximum temperature, minimum temperature and pan evaporation are used to evaluate the interrelationship of these climatic variables using regression model based on 35 years of weather data recorded at Ranchi (23 °23'N, 85 °23'E and alt. 610 m), the capital of Jharkhand state. Statistical analysis was carried out using Microstat software employing correlation and regression equation (stepwise and linear regression). Using the correlation coefficient, and significant correlations between parameters, the regression equations have been developed with one dependent parameter and one or more independent parameters. Regression equations were subsequently used to validate regression model using the derived parameters and observed data. It has been established that interrelationship of climatic variables can be evaluated accurately using regression models.

2 illus, 5 tables, 7 ref

014159   Kanchan Mala;Devendra Kumar (Soil and Water Conservation Engineering Dep, College of Technology, G.B. Pant Univ of Agriculture Technology, Pantnagar-263 145) : Unit hydrograph by least square method. Indian J Soil Conserv 2008, 36(1), 1-5.

Unit hydrograph for estimation of runoff hydrographs for the Kothuwatari watershed was developed by least square method. The regeneration and prediction performance of the method were evaluated based on visual inspection of runoff hydrographs and statistical measures such as integral square error, absolute relative error in peak and absolute relative error in estimated time to peak. The lower value of integral square error, absolute relative error in peak and zero value of absolute relative error in estimated time to peak suggest the adaptability of least square method for derivation of unit hydrograph for development of hydrographs for the watershed.

1 illus, 2 tables, 13 ref

014158   Jeetendra Kumar;Singh A K P (NO, Rajendra Agricultural Univ, College of Agricultural Engineering, Pusa-848 125) : Water retention characteristics and development of models for prediction of available water capacity of the soil. Indian J Soil Conserv 2008, 36(3), 169-71.

5 tables, 16 ref

014157   George C (Centre for Water Resources Development and Management, Sub Centre, Manimalakunnu, Oliyappuram P.O., Koothattukulam-686 679) : Rainfall runoff correlation for Manimala river basin in Kerala. Indian J Soil Conserv 2008, 36(3), 129-30.

1 illus, 2 tables, 4 ref

014156   Durbude D G (Hard Rock Regional Centre, National Institute of Hydrology, Belgaum, Karnataka) : Drought identification and characterisation of semi-arid districts of North Karnataka. Indian J Soil Conserv 2008, 36(1), 11-15.

Study was carried out to identify drought and its characteristics in the northern part of Karnataka. The results showed negative trends, in the entire area in the annual and seasonal rainfall departure from its normal for most of years indicating a deficit in rainfall. The area was observed to be experiencing a drought of moderate intensity with a recurrence interval of 4 to 5 years. The spatial distribution of various drought affected zones within the study area based on probabilistic approach have been carried out and mapped in a GIS environment. It revealed that the entire study area falls under moderate drought affected zone except a small part of Jamkhandi taluka in Bagalkot district and Gangavati taluka in Koppal district. With an average of two dry spells with a length of 22 days, the effective monsoon in the area commences from the last week of June. Hence, for formulating a drought mitigation strategy in this area, it is recommended that soil and water conservation measures be implemented and water harvesting measures be carried under watershed development programmes like contour bunding, nala plugging and constructing gabions structures etc., to conserve available water resources for subsequent life saving irrigation to crops during periods of dry spell.

1 illus, 3 tables, 10 ref

014155   Deshmuk S D;Hari K R;Diwan P;Basavarajappa H T (Geology Dep, Govt. V.Y.T.P.G.Autonomous College, Durg, Chhattisgarh) : Spinifex textured metabasalt of Sonakhan greenstone belt, Central India. Indian Mineralogist 2008, 42(1), 71-83.

The metabasalts of Baghmara Formation of late Archaean Sonakhan greenstone belt, exhibit spectacular pillow structure and hydrothermal alteration. The presence of spinifex texture, major element concentration and REE data suggest a komatiitic affinity for these metabasalts which is being reported for the first time from this area.

8 illus, 2 tables, 32 ref

014154   Chakraborty P B;Mandal A P N (Bidhan Chandra Krishi Viswavidyalaya, Regional Research Station (Coastal Saline Zone), Kakdwip-743 347) : Rainfall characteristics of sagar island in sundarban, West Bengal. Indian J Soil Conserv 2008, 36(3), 125-128.

Twelve years' (1990-2001) historical rainfall data of Sagar Island revealed that the total mean annual rainfall is 1924.19 mm and 50%of the years received more than the mean rainfall. Such variation had significant positive correlation (r = 0.924**) between rainfall and rainy days. However, maximum (148.23 mm) rain occurred in 29th week followed by 36th week. The rainfall was found to be bi-modal in nature having two peaks usually at 29th and 37th weeks, respectively. With years, shift in the peaks has been observed. In 41.7% of the years the first peak shifted to the month of July and/or August instead of June, whereas, the second peak shifted to the month of September in 57% of the years. Such shift was markedly observed after 1995 indicating a considerable change in climatic behaviour. However, the dependable rainfall at 76.90 probability is expected to occur in every year during 24th to 29th weeks. The monthly dependable rainfall is expected to occur in every year during the month of May to October with major concentration during June to September.

6 illus, 4 tables, 7 ref