014567   Muthuchami A;Sridharan S (NO, Regional Meteorological Cent, Chennai-600 006) : Role of cyclonic system in excess and deficit monsoon years in India. Mausam 2005, 56(4), 851-6.

Attempt has been made to study the rainfall features associated with cyclonic systems (Depressions and cyclonic storms) during excess and deficit monsoon years over the country. It is seen statistically that there is no significant difference in number of systems that formed during excess and deficit years. In the month of May systems travel mostly towards north in excess years whereas in deficit years they travel northwest ward. In June the formation positions during excess and deficit years have no significant difference in latitude of formation. In the case of longitude, the systems in excess monsoon years form slightly to the east compared to deficit years. In September the systems not only form at lower latitudes in deficit years but also they form close to coast in deficit years than in excess years. In September number of formation of systems in excess years is more than deficit years. El- Nino is not the major factor which controls the rainfall distribution in monsoon months.

5 illus, 1 table, 7 ref

014566   Muralidharan K;Lathika P (Dep of Statist, Bhavnagar Univ, Bhavnagar-364 002) : Statistical modelling of rainfall data using modified weibull distribution. Mausam 2005, 56(4), 765-70.

Presents the aspects of modeling rainfall data using a modified version of weibull distribution. This model takes care of those days reported with zero rainfall corresponding to the dry days (i.e., no rain day) during a season (in life testing context this situation is called instantaneous failures). Proposes a modified weibuli distribution as a suitable model to represent such situations by mixture of a singular distribution at zero and a two parameter weibull distribution. We derive Maximum Likelihood Estimates (MLE) of the parameters and their joint asymptotic distributions as well as that of the mean rainfall. Based on the above results a 95% confidence interval for the mean of the mixture distribution is obtained. The method is illustrated with actual measured data on rainfall from two stations namely, Jalgaon and Coimbatore divisions in India during a 10 year period from 1961 to 1970. Corresponds to each year, the estimates of the parameters, average rainfall and confidence intervals are provided.

4 illus, 2 tables, 20 ref

014565   Mondal N C;Singh V S (NO, Natn Geophys Res Inst, Hyderabad-500 007) : Effect of groundwater aquifers due to tannery industries in and around Dindigul town, Tamil Nadu, India. J appl Hydrol 2004, 17(2-3), 78-86.

There are about 80 tanneries operating in and around Dindigul town, Tamilnadu. The untreated effluents from the tanneries have considerably affected the quality of groundwater in the area. In order to arrest the extent of groundwater deterioration in the area, detailed analysis of groundwater quality data has been carried out. The concentration of cations such as Calcium (Ca²⁺), Magnesium (Mg²⁺), Sodium (Na⁺) and Potassium (K⁺) and anions such as Bicarbonate (HCO₃^-), Sulphate (SO₄^2-), Chloride (CL^-1 and Nitrate (NO₃^-) have been considered for 2000 and 2001 data sets in the study. Apart from these constituents, pH, Electrical Conductivity (EC), Total Dissolved Solid (TDS) and Total Hardness (TH) as CaCO3 also have been studied. The correlation of these constituents with the EC has been worked out for 2000 and 2001 data sets. For 2000 data set the highest correlation is found between EC and chloride with a correlation coefficient of 0.96. Progressive reduction in correlation coefficients for Na⁺, (Na⁺ + K⁺), TH, Ca²⁺ and Mg²⁺ are found 0.89, 0.88, 0.87, 0.85 and 0.83 respectively. But in the 2001 data set the correlation coefficient value in between EC and Cl^- is 0.99. From the study, it is inferred that the quality of groundwater in the area under investigations are deteriorated mainly due to extensive use of Sodium Chloride (NaCl) and Sodium Bicarbonate (NaHCO₃) in leather industries.

4 illus, 3 table, 11 ref

014564   Maurya D M;Patidar A K;Mulchandani N;Goyal B; Thakkar M G;Bhandari S;Vaid S I;Bhatt N P;Chamya L S (Dep of Geol, M.S. Univ of Baroda, Vadodara-390 002, Email: lschamyal@yahoo.com) : Need for initiating ground penetrating radar studies along active faults in India: An example from Kachchh. Curr Sci 2005, 88(2), 231-40.

The landscape of India has been shaped by multicyclic tectonic movements along the various fault systems whose origin and subsequent tectonic history are related to the break-up and the northward drift of the Indian plate. Many of the faults are seismogenic and have a long history of tectonic reactivation and present some of the best examples of sedimentation in fault-controlled basins. It is imperative that detailed shallow subsurface studies are carried out along these faults to understand their nature, potential for stress accumulation and release, neotectonic evolution and palaeoseismic events. Apart from providing detailed field studies involving mapping of faults, geomorphic features and reconstruction of the stratigraphy of Quaternary sediments, the article argues for extensive use of the Ground Penetrating Radar (GPR) primarily to delineate the subsurface geology along the various faults followed by trenching/excavation to reconstruct the neotectonic and palaeoseismic history. Briefly describe the salient features of GPR and also present as an example, the preliminary results of the first ever GPR surveys carried out by us along an active fault in Kachchh. GPR studies along the Katrol Hill Fault in Kachchh have helped in locating and understanding the nature of the fault and quantifying the amount of fault scarp retreat.

6 illus, 1 table, 50 ref

014563   Loe B R;Ali M;Joardar D (NO, India Meteorological Dep, New Delhi-110 003) : Synoptic systems associated with onset of southwest monsoon over Rajasthan. Mausam 2005, 56(4), 857-72.

Attempt has been made to identify the main synoptic features, which are responsible for onset of southwest monsoon over the two met sub divisions east and west Rajasthan for the period 1971-2004 based on modem observational technology and developed forecasting technique in the field of short-range prediction of monsoon surges. The low pressure systems (LPS) originate over Arabian Sea, especially the formation of MTC which indicates a good signature for predicting onset of monsoon, which is the prominent feature for causing onset of summer monsoon over Rajasthan. In addition LPSs form over Bay of Bengal moved in west to northwestwards direction and reach over Rajasthan and its neighbourhood region as a lopar or an upper air cycir, also brings monsoon over Rajasthan.

8 illus, 2 tables, 14 ref

014562   Kumari P;Sastri C V S;Srivastava A K (Div of Agric Phys, IARI, New Delhi) : Radar study on the heights of Cb clouds around Guwahati. Mausam 2005, 56(4), 910-14.

^ssc4 illus, 3 tables, 1 ref

014561   Kumar R;Singh K K;Sarkar S K (NO, Sch of Envir Sci Jawaharlal Nehru Univ, New Delhi-110 067) : Usefulness of medium range weather forecast in improving the quality of output from CROPGRO - Soyabean model. Mausam 2005, 56(4), 877-82.

CROPGRO-Soybean model calibrated for local conditions of Raipur has been used to evaluate the relevance of medium range weather forecast relative to the soybean crop growth period. A procedure that makes use of historical weather data, medium range weather forecast (mrwf) and current weather data in conjunction with the CROPGRO-Soybean model was developed to arrive at a probable distribution of predicted yield. A series of perfect mrwf for 5 days were assumed for assessing the sensitivity of the crop management system to forecast information. The relative importance by time of year was taken as a reduction in variance due to a perfect 5-day mrwf. The results of the study, conducted for two reference years 1986 (low-production year) and 1993 (high-production year) at Raipur, showed that the yield estimation can be done 20 days in advance before the physiological maturity for low-production year (1986) and 15 days in advance before physiological maturity for high-production year (1993). For both the years mrwf during reproductive phases are more valuable. It has also been concluded that the longer forecast periods are responding earlier in the growing season with higher values too.

9 illus, 1 table, 13 ref

014560   Kumar P (NO, Natn Law Univ, Jodhpur, Rajasthan) : Mathematical approach on size maximum wind, RMW and inflow angle in tropical cyclone. Mausam 2005, 56(4), 893-900.

^ssc3 illus, 1 table, 37 ref

014559   Kumar N;Roy Bhowmik S K;Ahmad N;Hatwar H R (NO, India Meteorological Dep, New Delhi-110 003) : Mathematical model for rotating stratified airflow across Khasi-Jayantia hills. Mausam 2005, 56(4), 771-8.

Two-dimensional meso-scale model has been considered to study mountain drag, momentum and energy fluxes across Khasi-Jayantia hills of India. The general expressions for mountain drag, momentum and energy fluxes are derived for stratified rotating fluid. It is found that decrease of wind speed reduces the magnitude of mountain drag, momentum and energy fluxes. As a result, the flow becomes nearly geostrophic. The study suggests that broaden of mountain or increase in latitude (i.e., increase in ƒ) reduces magnitude of mountain drag, momentum and energy fluxes. When results are compared with stratified non-rotating flow, a significant impact of Coriolis force in the mountain wave is noticed.

1 illus, 27 ref

014558   Khole M (NO, India Meteorological Dep, Pune-411 005) : Inter-annual and decadal variability of sea surface temperature (SST) over Indian Ocean. Mausam 2005, 56(4), 803-10.

Attempt has been made in the study to examine the inter-annual and inter-seasonal variability of SST over. Equatorial Indian Ocean (5° N- 5° S and 50° E - 100° E) and North Indian Ocean (5° N - 20° N and 50° E - 100° E), during the period 1961-98. The values of seasonal SST anomaly over these sectors of Indian Ocean are computed for the four standard meteorological seasons over India, viz., Winter (January - February), Pre-monsoon (March - May), SW Monsoon (June - September) and Post-Monsoon (October - December). The variability of seasonal SST anomaly is examined, using various standard statistical methods and procedures, on inter-annual as well as decadal time-scale and the results are inter-compared. The SST anomaly over both the above sectors of Indian Ocean, for all the four seasons, shows an increasing trend during 1961-98, more particularly and prominently, after mid-1970s.

6 illus, 21 ref

014557   Jenamani R K;Dash S K (NO, India Meteorological Dep, New Delhi-110 003) : Study on the role of synoptic and semi-permanent features of Indian summer monsoon on its rainfall variations during different phases of El-Nino. Mausam 2005, 56(4), 825-40.

Characteristics of different synoptic and semi-permanent features of Indian Summer Monsoon Rainfall (ISMR), such as monsoon disturbances (lows and depressions), monsoon trough and Tibetan anticyclone and duration of monsoon, are studied individually for different phases of El-Nino during the period 1960-98 to understand why during some El-Nino single events, ISMR was deficient while during other years, ISMR was on the positive side of normal or normal. This study examines cases of El-Nino double events with deficient and near deficient ISMR in one of the two years and in both the years respectively. The cases of deficient ISMR without any El-Nino are also discussed. Emphasis has been given on the effects of the synoptic and semi-permanent features on spatial variations of ISMR. Results show that characteristics of synoptic and semi-permanent features were important for ISMR and these were responsible for producing normal or above normal ISMR during some years in spite of El-Nino such as 1997. Also in the absence of El-Nino, ISMR was deficient because of less number of days of monsoon trough, lows and depressions, and weak Tibetan anticyclone. The reverse happened during flood years when there was no La-Nina. Statistical analysis indicates very high correlation coefficients (CCs) of these synoptic and semi-permanent features with ISMR than those of SST of Nino-3 region. India received highest monsoon rainfall during 1961 because total number of days of intense monsoon disturbances and monsoon trough and the total duration of monsoon over India during the year was the highest. This study shows that monsoon disturbances and monsoon trough are the most important components of synoptic and semi-permanent features, which affected spatial variation of ISMR in 1965 and 1966 with deficient rainfall and in 1961 and 1994 with excess rainfall over a large part of India.

8 illus, 4 tables, 36 ref

014556   Jayapaul D;Kundu A;Gaur M P;Krishnamurthy K V (Antarctica Div, Geol Surv of India, NH 5P, NIT, Faridabad-121001, Email: antgsi@vsnl.net) : Petrology of A-type hornblende granite and fayalite granite enclaves from cDML, East Antarctica: some constraints on their origin. J Geol Soc India 2005, 65(5), 562-76.

Skorvestallen batholith intrusive into granulitic crust consists of dominant coarse-grained pink granite, small rounded bodies of greenish grey fayalite granite, stocks of grey porphyritic biotite granite and porphyritic fayalite granite. These weakly peraluminous granites show A-type signatures with characteristic high Fe/(Fe + Mg), Ti/Mg, HFSE such as Y and Zr, LREE and Zn. The granites crystallized at high temperatures and were emplaced at mid-crustal pressures. The paper discusses their possible mode of origin based on petrochemical studies.

6 illus, 6 tables, 43 ref

014555   Hussain S M;SunderRaju P V (NO, Natn Geophys Res Inst, Hyderabad-500 007, Email: pvsraju@ngri.res.in) : Flute casts in BIF of Chitradurga schist belt, Karnataka. J Geol Soc India 2005, 65(5), 634-5.

Flute casts in the banded iron formation of the Chitradurga schist belt in the vicinity of Palvanahalli village, north of C.S. Halli have been reported.

^ssc3 illus, 1 table, 8 ref

014554   Gupta M K;Sharma R K (NO, India Meterological Dep, Pune) : New approach to pyranometer calibration. Mausam 2005, 56(4), 922.

^ssc1 table, 2 ref

014553   Gupta H K (Dep of Ocean Dev, Mahasagar Bhavan, Lodi Road, New Delhi-110 003, Email: dodsec@dod.delhi.nic.in) : Early warning system for oceanogenic disasters in Indian ocean (Tsunami and Storm surges): the indian initiative. J Geol Soc India 2005, 65(5), 634-46.

15 illus, 1 ref

014552   Guhathakurta P;Menon P A;Dikshit S K;Sable S T (India Meteorological Dep, , Pune-411 005) : Extreme rainfall analysis of Andhra Pradesh using a probability distribution model: a regional estimate. Mausam 2005, 56(4), 785-94.

Attempts to analyze the extreme rainfall events of Andhra Pradesh, a coastal state of Peninsular India, where both monsoon and post-monsoon seasons contribute significant rain. A network of 155 stations having data of seventy years or more during the period 1901-2000 has been used for the study. These stations are well distributed over the state. One-day, two-day and three-day extreme annual rainfall series are made and the isohyetal analysis demarcates three heavy rainfall receiving zones. Probability distribution functions have been fitted for the regional estimates of climate changes in extreme rainfall series of each station. Both the extreme value distribution viz., Gumbel and log normal distribution fit well with latter one giving slightly better fit over the former. Goodness of fit of the distribution is tested with Kolmugorov - Smimov Statistic.

8 illus, 2 tables, 13 ref

014551   Gopalakrishnan R (PPOD Div, AMSE Wing Geol Surv of India, Bangalore-560 078, Email: dharti@bgl.vsnl.net.in) : Preparation and certification of international rock standards. J Geol Soc India 2005, 65(5), 658-62.

^ssc37 ref

014550   Gopala Rao D;Krishna K S (Dep of Geol, Osmania Univ, Hyderabad-500 017, Email: drgopalarao@yahoo.com) : Compressional wave velocity and index properties of the gabbroic rocks drilled at hole 1105A of the Atlantis bank, Southwest Indian ridge. J Geol Soc India 2005, 65(5), 609-17.

Compressional wave velocities (Vp) and index properties of 70 mini- gabbroic rock- core samples of 2.5 cm diameter x 2.1 cm long from 157.1 m below seafloor in Hole 1105 A of the Atlantis Bank, Southwest Indian Ridge, were measured in the laboratory. Comparison of the Vps and onboard lithostratigraphy revealed that the Vps of the gabbros and olivine gabbros are very close and have the values 6.74±0.04 and 6.7±0.07 km/s, respectively. Oxides and oxide olivine gabbros have markedly lower Vps (6.53±0.076 and 6.59±0.077 km/s) respectively as abundance of Fe-Ti oxide minerals vary as a result of alteration processes. They are also consistent with well-log results of Hole 1105A and Hole 735 B from the bank. The mean bulk density of the rocks is 2.93±0.15 gm/c³. The other index properties-porosity, void ratio and grain density and their means are consistent with model populations of the rock minerals.

8 illus, 2 tables, 7 ref

014549   Diwan H D;Kuity D P;Maity D K (NO, Sch of Stud in Geol & WRM Pt R.S. Univ, Raipur-492 001) : Impact of land degradation on flood plains of lower Kharun river, Raipur, Chhattisgarh. J agric Issues 2003, 8(1-2), 19-24.

The flood plains constitute an important geomorphic unit in a fluvial landscape by virtue of fertile soil and ample water resource. The capital of Chhattisgarh state Raipur situated on the left bank of lower Kharun where soil excavation for brick making is an on going process. The resulting deteoration of the riparian tract is a discernible feature. The assessment of the land degradation in this dilatent area, due to soil mining and erosion, protective measures for soil conservation and reclamation of lands has been carried out. Various geomorphic features and soil categories were mapped using IRS LISS II FCC data with limited field checks. Geologically the area is represented by Chhattisgarh Super group sedimentary rocks of Proterozoic age including Deodongar Sandstone, Raipur Shale and Stromatolitic Limestones. The geomorphic study shows that palaeochannels, meander scar, karst features, island and river terraces are common features as observed near Akola, Kumhari, Atari & Bahesar areas. Four major soil groups locally named, as Bhata, Kanhar, Dorsa and Matasi & Alluvium are present in the inadvertently modified area, representing catenary in nature. The old flood plains of Kharun contain prolific alluvial soil where agricultural farming is practiced. It is observed that excavation of soils from, flood plains has modified the natural landscape. The ditches and ponds developed on plains around Sarona, Chikli and Bhatagaon villages. The natural drainages have been obstructed and blocked by dumps, which leads to soil erosion and gulley erosion on banks. The study shows that about 16% of flood plain unit has been affected by soil mining and erosion . The belt of the Kharun River suffers a slow process of modification because of insufficient flow of water except during flood seasons. For reclamation of lands the conservation measures like bunds, gulley plug, back filling of ponds, revegetation and plantation of suitable species like Eucalyptus Camldulensis, Acacia arrciculifermis etc. and river training structures are suggested.

2 tables, 6 ref

014548   Deepthy R;Balakrishnan S (Dep of Earth Sci, Pondicherry Univ, Pondicherry-605 014, Email: sbala-2002@yahoo.com) : Climatic control on clay mineral formation evidence from weathering profiles developed on either side of the Western Ghats. J Earth Syst Sci 2005, 114(5), 545-56.

Attempt is made to understand how the nature of clay minerals formed due to weathering differs in tropical regions receiving high and low rainfall. Clay mineralogy of weathering profiles in west coast of India, which receives about 3 m rainfall through two monsoons and those from the inland rain-shadow zones (<60> 200 cm rainfall) are studied using X-ray diffraction technique. In the west coast, 1:1 clays (kaolinite) and Fe-Al oxides (gibb-site/goethite) are dominant clay minerals in the weathering profiles while 2:1 clay minerals are absent or found only in trace amounts. Weathering profiles in the rain shadow region have more complex clay mineralogy and are dominated by 2:1 clays and kaolinite. Fe-Al oxides are either less or absent in clay fraction. The kaolinite-smectite interstratified mineral in Banasandra profiles are formed due to transformation of smectites to kaolinite, which is indicative of a humid paleo-climate. In tropical regions receiving high rainfall the clay mineral assemblage remains the same irrespective of the parent rock type. Rainfall and availability of water apart from temperature, are the most important factors that determine kinetics of chemical weathering. Mineral alteration reactions proceed through different pathways in water rich and water poor environments.

8 illus, 2 tables, 31 ref

014547   Chandra H;Sharma S;Acharya Y B;Jayaraman A (Phys Res Lab, , Navrangpura, Ahmedabad-380 009) : A Rayleigh lidar study of the atmospheric temperature structure over Mt. Abu, India. J Indian Geophys Union 2005, 9(4), 279-98.

A Nd-YAG laser based Rayleigh Lidar was set up at Guru Shikhar, Mount Abu (24.5° N, 72.7° E, altitude 1.7 km) by the Physical Research Laboratory to study the temperature structure in the altitude region of 30-75 km at tropical latitudes. Temperature profiles are derived from relative density measurements, following the method described by Hauchecorne & Channin (1980). Photon counts are averaged over one hour (2 hour during the later phase) in time and 480 m in altitude. Measurements were made for about 5 nights of each month around new rnoon except the monsoon season (June-August). Temperature profiles obtained on 109 nights during the period November 1997 to November 2001 are used to derive average temperature profile for each month (September to May) and are compared with the CIRA-86 model. Observed temperature profiles are in good agreement with CIRA-86 below 50 1cm but are higher by up to 10 K above 50 km. The agreement is better during winter months. The temperature profiles are also compared with the equatorial model for the Indian region (Sasi & Sengupta 1979) based on rocket and balloon measurements. Day to day variability is less than ± 5 K for altitudes below 50 km and up to ± 10 K around 70 km. The variability is the least around 40-50 km. The mean values of the stratopause level and temperature are found to be 48 km and 271 K respectively over the measurement site. Seasonal variation of the temperature below 60 km shows equinoctial and summer maxima whereas above 70 km winter maximum with equinoctial minima are seen.

16 illus, 2 tables, 40 ref

014546   Biswas B K (Meteorological Office, C.S.I. Airport, Mumbai) : Diurnal variation of monsoon low clouds over Chhatrapati Shivaji International Airport, Mumbai. Mausam 2005, 56(4), 907-10.

1 illus, 1 table, 3 ref

014545   Bhattacharya R (Dep of Envir Sci, Univ of Kalyani, Kalyani-741 235) : Calculation of the variability of the window channel frequency near 90 GHz for four Indian stations. Mausam 2005, 56(4), 873-6.

Shift of millimeter wave window frequencies owing 10 changes of water vapour concentration for four Indian stations having different climatic behaviours have estimated for horizontal mode of propagation. Difference in specific attenuation at minimum and maximum humidity for 94 GHz and corresponding window frequencies are also analysed.

1 illus, 1 table, 5 ref

014544   Bhattacharjee I;Mukundhan A R;Sachan A S; Tiwary K N;Sinha R M;Gupta R K (Dep of Atom Energy, Atom Miner Directorate for Explor and Res, Nagpur-440 001) : Proterozoic unconformity related uranium mineralisation around Chitakhol, Kobra district, Chhattisgarh, India. J Geol Soc India 2005, 65(5), 619-23.

The paper reports for the first time uranium mineralisation along the northern fringes of the late Proterozoic Chhattisgarh basin that enhances the potential of the region to host unconformity related uranium deposits.

^ssc1 illus, 12 ref

014543   Bhagat D K U R (NO, India Meteorological Dep, Pune-411 005) : Absolute angular momentum generation & its vertical transport in the field of mid-tropospheric cyclones. Mausam 2005, 56(4), 759-64.

A quasi-stationary synoptic system is usually seen on the weather charts during southwest monsoon period over the north-east Arabian Sea and adjoining area of Gujarat and north Konkan. The transport of absolute angular momentum, for the atmospheric weather systems, plays a significant role during the southwest monsoon period. The mean absolute angular momentum and its vertical transport associated with MTC have been discussed. The expected accumulation of momentum throughout the troposphere upto 800 km around the centre of MTC has been calculated and displayed. The transport of angular momentum to the underlying surface and momentum loss or gain has also been discussed. Estimates have been made of surface stress by means of angular momentum transferred. The study reveals that the flux of angular momentum found to be dominated mostly between surface and 500 hPa and the values of shearing stress are positive from the centre of MTC to 500 km.

2 illus, 1 table, 22 ref

014542   Bawiskar S M;Chipade M D;Puranik P V;Bhide U V (NO, Indian Inst of Trop Meteorology, Dr. Homi Bhabha Road, Pune-411 008, Email: bawiskar@hotmail.com) : Energetics of lower tropospheric planetary weaves over mid latitudes: Precursor for Indian summer monsoon. J Earth Syst Sci 2005, 114(5), 557-64.

Based on NCEP/NCAR reanalysis data, kinetic energy and momentum transport of waves 0 to 10 at 850 hPa level are computed from monthly mean zonal (u) and meridional (v) components of wind from equator to 90°N. Fourier technique is used to resolve the wind field into a spectrum of waves. Correlation analysis between All India Seasonal Monsoon Rainfall (AISMR) and energetics of the waves indicates that effective kinetic energy of waves 1, 3 and 4 around 37.5°N in February has significant correlation (99.9%) with the subsequent AISMR. A simple linear regression equation between the effective kinetic energy of these three waves and AISMR is developed. Out of 47 years' (1958-2004) data, 32 years (1958-1989) are utilized for developing the regression model and the remaining 15 years (1990-2004) are considered for its verification. Predicted AISMR is in close agreement with observed AISMR. The regression equation based on the dynamics of the planetary waves is thus useful for Long Range Forecasting (LRF) of AISMR. Apart from the regression equation, the study provides qualitative predictors. The scatter diagram between AISMR and effective kinetic energy of waves 1, 3 and 4 around 37.5°N indicates that if the kinetic energy is more (less) than 5m²s^-2, the subsequent monsoon will be good (weak). Stream function fields indicate that high latitude trough axis along 40°E (70° E) leads to a good (weak) monsoon over India.

8 illus, 1 table, 13 ref

013364   VEnugopal T;Seetaramayya P;Dhakate A R (NO, Indian Inst of Trop Meteorology, Dr. Homi Bhabha Road, Pashan, Pune 411 0081, Email: tvgopal@tropmet.res.in) : Interrelationship between cloud cover and Sensible heat flux over land during MONTBLEX-1990. J Earth Syst Sci 2005, 114(4), 421-6.

Micro-meteorological tower observations of MONTBLEX (Monsoon Trough Boundary Layer Experiment-1990, combined with routine surface observations at Jodhpur in the dry convective sector of Indian summer monsoon trough are used to examine the interrelationship between total cloud cover (TCC) and surface sensible heat flux (SHF) during the summer monsoon of 1990. A significant inverse relationship between TCC and SHF is found during various Intensive Observation Periods of the experiment. This relationship holds for the various methods of estimation of SHF.

5 illus, 1 table, 10 ref

013363   Sukumaran S;Ravindra Kumar G R;Srikantappa C (NO, Cent for Earth Sci Stud, Akkulam, Trivandrum-695 031, Email: grrkjmar@nid4.vsnl.net.in) : Charnockite forming metamorphism in Palghat, Southern India: a fluid inclusion study of gneiss, charnockite, charnoenderbite and pegmatite. J Geol Soc India 2005, 66(6), 679-94.

Palghat region in southern India presents excellent examples of fluid controlled gneiss to charnockite transition zones. The paper constitutes results of detailed fluid inclusion studies carried out to understand the nature and role of fluids, across transition zones of such transformations and in associated charnoenderbite and pegmatite. Fluid inclusion petrographic studies suggest presence of at least three generations of fluid inclusions in different rock types viz., CO₂, CO₂-H₂O, and CO₂-H₂O-NaCl. The high-density CO₂ inclusions (1.03 to 0.91 g/cc) are characteristics of charnoenderbites with moderate density CO₂ inclusions (0.92 to 0.70 g/cc) in hornblende gneiss and relatively low CO₂ density (0.84 to 0.71 g/cc) inclusions in arrested charnockites. Salinities range from 2 to 35 wt.% NaCl equivalent. Majority of the inclusions are low-density CO₂, indicating preferential leakage and re-entrapment of these inclusions under shallower conditions. In charnoenderbites, a distinct bi-modal distribution in CO₂ densities is documented with early high-density CO₂ inclusions, trapped under higher pressure, deep seated conditions and a late, low-density CO₂ inclusions trapped under relatively shallower conditions. Occurrence of generally low-density CO₂ inclusions in the arrested charnockites suggest release and re-entrapment of CO₂ inclusions along structurally controlled weak zones. The higher concentration of low-density monophase CO₂ inclusions in the arrested charnockites and pegmatite are interpreted as a result of selective removal of H₂O from the mixed CO₂-H₂O inclusions, during ductile and ductile-brittle shear deformation. The CO₂ inclusions showing large density differences between the early charnockites (charnoenderbite) and late (arrested) charnockites are suggestive of entrapment at different periods and that the CO₂ densities of the charnoenderbite have been re-equilibrated during the latest tectono-metamorphic event. The fluids responsible for the formation of arrested charnockites are low P-T type late fluids, formed at a shallower, mid crustal levels. The study further illustrates major role of saline brines in the formation of arrested charnockites.

6 illus, 3 tables, 59 ref

013362   Sisodia M S;Singh U K;Lashkari G;Shukla P N; Shukla A D;Bhandari N (Dep STOPWORD Geol, JNV Univ, Jodhpur-342 005, Email: bhandari@prl.ernet.in) : Mineralogy and trace element chemistry of the siliceous earth of Barmer basin, Rajasthan: evidence for a volcanic origin. J Earth Syst Sci 2005, 114(2), 111-24.

The presence of a 3-5 cm thick loose fragmental layer in the Siliceous Earth at Matti ka Gol in the Barmer basin of Rajasthan has been reported. Petrographic, chemical and mineralogical study reveals the presence of abundant volcanic dibris such as glass shards, agglutinates, hollow spheroids, kinked biotites, feldspars showing oscillatory zoning, olivines, ilmenite and native iron. The presence of similar particles in the whole section suggests that the Siliceous Earth is a volcanic ash. Stratigraphic correlation, palynological and microvertebrate data suggest that the Siliceous Earth may have deposited over a short span of time during the Upper Cretaceous to Lower Palaeocene. In view of the possibility that this section may contain K/T impact debris, for grains having impact signatures were looked for. Some patches of the Siliceous Earth of Bariyara show the presence of Ni-rich (<62> 0.5%) vesicular glasses, sanidine spherules, magnesioferrite crystals, soot, etc., but because of their low abundance, it is not possible to establish if they are volcanic, micrometeorite ablation products or a part of the K/T impact ejecta.

12 illus, 1 table, 23 ref

013361   Singh R;Pal P K;Kishtawal C M;Joshi P C (Atmospheric Sci Div Meteorology STOPWORD Oceanography Grp Space Appli, ISRO, Ahmedabad 380 015, Email: randhir_h@yahoo.com) : Impact of bogus vortex for track and intensity prediction of tropical cyclone. J Earth Syst Sci 2005, 114(4), 427-36.

Initialization scheme designed to improve the representation of a tropical cyclone in the initial condition is tested during Orissa super cyclone (1999) over Bay of Bengal using the fifth-generation Pennsylvania State University - National Center for Atmospheric Research (Penn State - NCAR) Mesoscale Model (MM5). A series of numerical experiments are conducted to generate initial vortices by assimilating the bogus wind information into MM5. Wind speed and location of the tropical cyclone obtained from best track data are used to define maximum wind speed, and centre of the storm respectively, in the initial vortex. The initialization scheme produced an initial vortex that was well adapted to the forecast model and was much more realistic in size and intensity than the storm structure obtained from the NCEP analysis. Using this scheme, the 24-h, 48-h, and 72-h forecast errors for this case was 63, 58, and 46 km, respectively, compared with 120, 335, and 550 km for the non-vortex initialized case starting from the NCEP global analysis. When bogus vortices are introduced into initial conditions, the significant improvements in the storm intensity predictions are also seen. The impact of the vortex size on the structure of the initial vortex is also evaluated. Author has found that when the radius of maximum wind (RMW) of the specified vortex is smaller than that of which can be resolved by the model, the specified vortex is not well adapted by the model. In contrast, when the vortex is sufficiently large for it to be resolved on horizontal grid, but not so large to be unrealistic, more accurate storm structure is obtained.

10 illus, 19 ref

013360   Selvaraj K;Ram Mohan V;Jonathan M P; Srinivasalu S (Inst STOPWORD Mar Geol STOPWORD Chem, Natn Sun Yat-Sen Univ, Kaohsiung 804, Taiwan. R.O.C., Email: kselva8@yahoo.com) : Modification of a coastal environment: vedaranniyam wetland, southeast coast of India. J Geol Soc India 2005, 66(5), 535-8.

The study of SPOT (1988) and IRS-1C (1998) images along with topographic maps (1928 and 1969-70) indicates that the wetland of Vedaranniyam has undergone significant landform modifications over a period of 70 years (1928-1998). Changes in shape and extent of the Mullippallam and Serattalaikkadu creeks, migrating confluence of stream Koraiyar towards north, development of mangrove vegetation, progradation and retrogradation of shoreline and increasing number of salt pans are determined and quantified. The study shows that fluctuations in the discharge of river flows and sediment loads associated with NE monsoon intensity and human interference through salt pan and agricultural activities are mainly responsible for the dynamic changes observed in the area.

1 illus, 2 tables, 3 ref

013359   Sarkar B C (Dep STOPWORD Appl Geol, Indian Sch of Mines, Dhanbad-826 004, Email: bhabesh_ sarkar@ hotmail.com) : Developments in geomathematical modelling and computer applications in mineral resources assessment. J Geol Soc India 2005, 66(6), 713-24.

Geomathematical techniques are gaining importance for analysis of geological data. The aim of geomathematical modelling is to replicate the reality as closely as possible using available sample information. In the case of a mineral deposit, geomathematical modelling provides a closer representation of the geological reality in terms of distribution of various spatial parameters in order to assess its 3D spatial configuration. Geomathematical modelling involves filling & mathematical function, f(x) to define adequately a mineral deposit with respect to the distribution of its size, shape, grade, density, thickness and other geological attributes, viz. petro-mineralogical characteristics with an aim to provide a three dimensional representation of the deposit with maximum possible confidence. This paper discusses the developments in geomathematics and focuses on the recent trends along with the computer applications in mineral resources assessment.

2 illus, 66 ref

013358   Sahay A;Srivastava D C (Dep STOPWORD Earth Sci, IIT Roorkee, Roorkee-247 667, Email: dpkesfes@iitr.ernet.in) : Hourglass structure: an evidence of buckle folding. J Geol Soc India 2005, 66(6), 673-7.

The Nimbahera shale beds show an hourglass map pattern due to juxtaposition of an anticline and a syncline along a common NNE striking, upright axial plane. Several possible hypotheses, such as superposed folding, sheath folding, variation in shortening, variation in orientation of pre-existing S- surfaces and coalescence of fold waves are tested for explaining the development of the hourglass structure. Evidence from geometrical characteristics of the folds, associated mesoscopic scale structures and the published experimental results suggest that the hourglass structure has developed due to the linkage of the two out-of-phase fold waves that propagated towards each other during the folding of the Nimbahera shale beds by buckling.

4 illus, 8 ref

013357   Rajaram R;Srinivasan M (C STOPWORD S STOPWORD Mar Biol, Annamalai Univ, Parangipettai-608 502) : Bio amplification of mercury in the food-chain due to industrilization Uppanar estuary, bay of Bengal, India. J Ecotoxic envir Monit 2005, 15(4), 355-64.

Mercury content and flow in the estuarine environment at Uppanar estuary, Cuddalore, Tamil Nadu has been studied for the period of two years from June 1998 to May 2000. Estuarine water contained mercury from non-detectable level (N.D) to 1.92 μg l^-1), sediment (0.17 to 6.17μg g^-1), phytoplankton (N.D to 6.87μg g^-1'), zooplankton (0.47 to 8.81μg g^-1) and various parts in bivalve Meretrix casta (foot-N.D to 6.42μg g^-1 & muscle-N.D to 5.48 μg g^-1) and fish Mugil cephalus (gill 0.09 to3.1μgg^-1; liver-0.11 to3.92μgg^-1; kidney-N.D to 2.1μg g^-1 & muscle-N.D to 0.23μg g^-1). Concentration of mercury in top level food-chain organisms like fish showed sufficient at present.

4 illus, 36 ref

013356   Prasad D S V V D;Rama Rao P V S;Uma G;Gopi Krishnas;VEnkateswarlu K (Dep STOPWORD Phys, Andhra Univ, Visikhapatnam-530 003) : Geomagnetic activity control on VHF scintillations over an Indian low latitude station, Waltair (17.7°N, 83.3°E, 20°N dip). J Earth Syst Sci 2005, 114(4), 437-41.

Using the data of amplitude scintillations recorded at 244 MHz from the geostationary satellite,FILEETSAT (73°E) at a low latitude station, Waltair (17.7°N. 83.3°E, 20°N dip), during the increasing sunspot activity period of 1997-2000, the effect of the geomagnetic storms on the occurrence of ionospheric scintillations has been studied. A total of 60 SC storms studied during this period, following the Aarons' criterion, reveals that the local time of onset of the recovery phase of the geomagnetic storms play an important role in the generation or inhibition of the ionospheric irregularities. Out of the 60 storms studied, nearly 60 to 70% satisfied the categories I, II and III of Aarons' criteria. However, in the remaining 30 to 40% of the cases, no consistent results were observed. Thus, there is a necessity for further investigation of the effect of geomagnetic storms on

3 illus, 15 ref

013355   Phartiyal B;Kotlia B S (NO, Birbal Sahni Inst of Palaeobotany, 53 University Road, Lucknow-226 007, Email: binitaphaniyal@yahoo.com) : A geomagnetic excursion event at <126>20,000-19,000 years BP recorded from the palaeolake sediments of Pithoragarh and Champawat districts, Uttaranchal. J Geol Soc India 2005, 66(5), 623-33.

Episodic tectonic disturbances during Late Quaternary period in the Kumaun Himalaya have led to the reactivation of the thrusts/faults in the zones of major intracrustal boundary thrusts thereby blocking the ancient drainage and resulting in formation of lakes. Such tectonic lakes were drained out due to further tectonic disturbances leaving behind their sedimentary records. In such two palaeolake profiles, one at Champawat district (Phulara and Chauki sections) and the other at Pithoragarh district (Riyasi section) of the Uttaranchal state in Kumaun Lesser Himalayas, a reversal (geomagnetic excursion) is recorded at 20,900-19,100 yrs BP. The reversal is found at both the places at the same time though being separated by an aerial distance of about 30 km and being parts of two different palaeolake systems placed in two different tectonic setups. Such excursions have been previously reported in the Kumaun Himalayas (Kotlia et al. 1998) as well as NW Himalaya (Sangode et al. 2002).

8 illus, 2 tables, 47 ref

013354   Pandey B K;Krishnamurthy P (NO, Geochronology Lab, Begumpet, Hyderabad-500 016, Email: upkishore@rediffmail.com) : Geochronology (Rb-Sr, Sm-Nd and Pb-Pb) of the proterozoic granulitic and granitic rocks around Usilampatti, Madurai district, Tamil Nadu: implication on age of various lithounits. J Geol Soc India 2005, 66(5), 539-51.

Rb-Sr, Sm-Nd and Pb-Pb systematics on mafic granulites, intermediate-charnockiies, charnockites, calc-granuliies, orthogneisses. leptyniles, granites and two (2) mineral samples (microcline and muscovite) from pegmatite have been studied. Sm-Nd model ages (TDM) for most of the rocks cluster around 2.1 Ga. Calc-granulites gave Rb-Sr whole rock isochron age of 1339 ± 110 Ma with initial ⁸⁷Sr/⁸⁶Sr ratio (I.R.) = 0.709. Mesoproterozoic age for the Meiasedimentary Group of rocks (calc-granulites) has been inferred based on their ⁸⁷Sr/⁸⁶Sr ratio also. Granites and leptynites have yielded Rb-Sr whole rock isochron ages of 823 ± 38 Ma, with I.R. = 0.713 and 894 ± 82 Ma. with I.R. = 0.708 respectively which are younger than the calc-granulites. Microcline and muscovite from pegmatite gave Rb-Sr model ages as 532 and 491 Ma respectively. Granites, leptynites and calc-granulites are derived from the crustal source as indicated by their high initial ⁸⁷Sr/⁸⁶Sr ratios. Most probably the protolith of the granitic and granulitic rocks is of Palaeoproterozoic age in this part of the Madurai Block. The minimum age of granulite grade of metamorphism has been inferred at c. 850 Ma, indirectly on the basis of Rb-Sr ages of leptynites, which normally form during the evolution of granulite facies assemblages. Both granulite facies metamorphism and granitic inagmatism probably took place during Neoproterozoic period correctable to the early phase of Pan-African orogeny. Later decompression, causing mineral scale resetting of the Rb-Sr arid Sm-Nd systematics, around 450-550 Ma, may correspond to the final exhumation, which brought the middle to lower crustal granulites to upper crustal levels, during the last phase of Pan-African activity. As per ages obtained on various lithounits in the present study the Metasedimentary Group of rocks (Mesoproterozoic) are younger than the Chamockite Group of rocks (Palaeoproterozoic) followed by the rocks belonging to the Migmatite Complex (Neoproterozoic).

8 illus, 6 tables, 45 ref

013353   Naik S;Patel R K (Dep STOPWORD Chem, Natn Inst of Technol, Rourkela-769 008) : Water quality of Nrusinghnath spring. Indian J envir Prot 2005, 25(6), 539-61.

Nrusinghnath is a place of piligrimage in the Padampur subdivision of Bargarh district on the northern flank of Gandhamardhan range of western Orissa. Physico-chemical study of the Nrusinghnath spring water has been carried out to establish the possible relationship among various parameters. The result of study gives necessary information about the quality of water at and around the spring.

1 table, 6 ref

013352   Mathur V K;Srivastava D K (Palaeont Divison, Geol Surv of India, Sector-E, Aliganj, Lucknow-226 024, Email: vinodmathur1954@rediffmail.com) : Early cambrian ichnofossils and inarticulate brachiopods from the Tal Group, Sirmaur district, Himachal Lesser Himalaya, India. J Geol Soc India 2005, 66(5), 581-90.

The assemblage of ichnofossils and inarticulate brachiopods are recorded and described systematically from the Early Cambrian rocks of Tal Group exposed in Nigalidhar and Korgai synclines, Himachal Lesser Himalaya, India. The ichnofossil assemblage occurring in the rocks of Arenaceous Member of Deo ka Tibba (Lower Tal) Formation and Quartzite Member of Dhaulagiri (Upper Tal) Formation. Tal Group exposed in Rayon-Koti Dhaman section of Nigalidhar Syncline contains Bergaueria sp., Cruziana sp., Didymaulichnus sp., Manomorphichnus Sp., Neonereites biserialis, Palaeophycus sp., Plagiogmus sp., Planolites sp., Rusophycus sp., Skolithos sp. and Treptichnus sp. A few iehnofossils i.e. Palaeophycus sp., Planolites sp. and Skolithos sp. have also been recorded from the Arenaceous Member of Deo ka Tibba Formation exposed in Birpa - Bhitar ka Khala section in the Korgai Syncline. This ichnofossil assemblage is known worldwide in the Early Cambrian (Upper Meishucunian to Lower Qiongzhusian) rocks and is correlatable with Ichnozone - III {Crimes, 1987). The inarticulate brachiopods viz. Lingulella sp., Magnicanalis sp., Mickwitzia sp., Obolella sp. and Obolus sp. of Tsanglangpuian Stage (Early Cambrian) occur alongwith ichnofossils namely, Palaeophycus sp. and Planolites sp. in the shale unit of Quartzite Member of Dhaulagiri Formation, Tal Group exposed in Birpa -Bhitar ka Khala section of Korgai Syncline.

3 illus, 32 ref

013351   Manglik A (NO, Natn Geophys Res Inst, Hyderabad-500 007, Email: ajay@ngri.res.in) : Moving boundary solution for solidification of lava lake and magma intrusion in the presence of time-varying contact temperature. J Earth Syst Sci 2005, 114(2), 169-76.

During the solidification of a lava lake heat is released convectively from the top surface as well as conductively into the country rock from the base, leading to non-uniform solidification. The upper solidified layer grows at a faster rate than the lower solidified layer. Similarly, solidification of magma intrusion within the crust is also non-uniform due to the presence of thermal gradient in the crust. Available analytical solution for solidification of a melt layer assumes only symmetric cooling about the centre of the layer. A moving boundary solution for thermal evolution and non-uniform solidification of a melt layer incorporating time-varying contact temperature conditions at both of its boundaries is developed. The solution is obtained by using the Fourier spectral approach in the space domain and a modified finite difference scheme in the time domain, and is validated with available analytical solutions for simple cases and a semi-analytical solution for the case involving temperature gradient in the country rock. This solution can be used to analyse solidification of lava lakes and magma intrusions experiencing time-dependent temperature variation at their contacts with the country rock.

4 illus, 24 ref

013350   MAlik N J;MAthew G (Dep STOPWORD Civ Engng, Indian Inst of Technol Kanpur, Kanpur-208 016, Email: javed@iitk.ac.in) : Evidence of paleoearthquakes from trench investigations across Pinjore Garden fault in Pinjore Dun, NW Himalaya. J Earth Syst Sci 2005, 114(4), 387-400.

Pinjore Garden Fault (PGF) striking NNW-SSE is now considered one of the active faults displacing the younger Quaternary surfaces in the piggyback basin of Pinjore Dun. This has displaced the older Kalka and Pinjore surfaces, along with the other younger surfaces giving rise to WSW and SW-facing fault scarps with heights ranging from 2 to 16 m. The PGF represents a younger branch of the Main Boundary Thrust (MET) system. An <126> 4 m wide trench excavated across the PGF has revealed displacement of younger Quaternary deposits along a low angle thrust fault. Either side of the trench-walls reveals contrasting slip-related deformation of lithounits. The northern wall shows displacement of lithounits along a low-angle thrust fault, while the southern wall shows well-developed fault-related folding of thick sand unit. The sudden change in the deformational features on the southern wall is an evidence of the changing fault geometry within a short distance. Out of five prominent lithounits identified in the trench, the lower four units show displacement along a single fault. The basal unit 'A' shows maximum displacement of about To = 2.85m, unit B = 1.8m and unit C = 1.45m. The displacement measured between the sedimentary units and retro-deformation of trench log suggests that at least two earthquake events have occurred along the PGF. The units A and D mark the event horizons. Considering the average amount of displacement during one single event (2 m) and the minimum length of the fault trace (<126> 45km), the behaviour of PGF seems similar to that of the Himalayan Frontal Fault (HFF) and appears capable of producing large magnitude earthquakes.

11 illus, 21 ref

013349   Maiti S;Meena N K;Sangode S J;Chakrapani G J (Dep STOPWORD Earth Sci, Indian Inst of Technol, Roorkee-247 667, Email: gjcurfes@iitr.ernet.in) : Magnetic susceptibility studies of soils in Delhi. J Geol Soc India 2005, 66(6), 667-72.

An atlas of magnetic anomalies in soils has been prepared for the first time for the city of Delhi, capital of India and one of the most populous and urbanized city in the world. The study reveals that magnetic susceptibility for Delhi top soils (0-15cm) coincide with either industrial sources of pollutants or natural anomalies. The result shows low field mass-specific susceptibility value ranging for different observed classes as industrial (3.02-531 x 10^-5 m³/kg), traffic areas (0.48-100.67 x 10^-5 m³/kg) and natural sections (0.02-6.8 x 10^-5 m³/kg). Frequency dependent susceptibility shows quite high median value of 8.67% for older pit samples (depth samples), followed by 5,88% in present (top soils) and lowest for industrial samples (1.67%). The-present study is a preliminary investigation on the environmental magnetic progress.

^ssc4 illus, 1 table, 17 ref

013348   Khosla S C;Nagori M L (Dep STOPWORD Geol, Mohanlal Sukhadia Univ, Udaipur-313 002, Email: sckhosla@yahoo.com) : A restudy of ostracode fauna from the inter-trappean beds of Anjar, Kachchh district, Gujarat. J Geol Soc India 2005, 66(5), 573-80.

Fifteen species of Ostracoda arc recorded from the freshly exposed inter-trappean beds along the newly constructed broad gauge railway line near Viri village. SSW of Anjar town, Kachchh district. Four species are assigned to the taxa previously described from the Inter-trappean beds of Anjar, seven species to the taxa described from Lakshmipur and one species to the taxon described from Mohagaonkala (Mohgaon-Kala), M.P. The taxonomy of three species - Lakshmipur and Jabalpur respectively are revised. The first two species are described as new and the third transferred to the genus Limnocypridea Lyubimova. Other species are also illustrated in the paper.

3 illus, 19 ref

013347   Karunakaran K;Samson Nesaraj A;Manjunathan S; Dorothy A;Raja M;Srividhya D (Dep STOPWORD Sci, Sona Coll of Technol, Salem-636 005) : Physico-chemical characteristics of groundwater in Salem corporation. Indian J envir Prot 2005, 25(6), 510-12.

Groundwater samples collected zonal-wise from different localities in Salem corporation were analyzed for their physico-chemical characteristics. A correlation analysis has been carried out among the various parameters. This analysis resulted in significant linear relationship between the following water quality parameters, namely Ca²⁺, Mg²⁺, Na⁺, K⁺, CO^2-₃, HCO^-₃, OH^-, Cl^-, F^-, and SO₄^2-. The usefulness of these parameters in predicting groundwater quality characteristics has also discussed.

4 tables, 4 ref

013346   John M M;Balakrishnan S;Bhadra B K (Dep STOPWORD Earth Sci, Pondicherry Univ, Pondicherry-605 014, Email: sbala_2002@yahoo.com) : Contrasting metamorphism across Cauvery Shear zone, South India. J Earth Syst Sci 2005, 114(2), 143-58.

Palghat Cauvery Shear Zone (CSZ) is a major shear zone that possibly extends into different fragments of Gondwanaland. In the study, mafic granulites occurring on either side of the CSZ in Namakkal area, southern India are examined. Textural features recorded in the mafic granulites are crucial in elucidating the metamorphic history of the southern granulite terrane (SCT). In the mafic granulites occurring to the south of CSZ, evidence of garnet breaking down during near isothermal decompression (ITD) is indicated by the development of orthopyroxene + plagio-clase moats in between quartz and garnet. The presence of comparatively small elongated second generation garnet embedded in pyroxenes from the mafic granulites occurring to the north of CSZ is indicative of the garnet formation via reaction between pyroxenes and plagioclase. which occurred during isobaric cooling (IBC). Rocks occurring to the south of CSZ have recorded comparatively higher temperature and pressure (849°C and 9.6 kbar) than those occurring to the north of the CSZ (731°C and 8.6 kbar) using conventional geothermobarometry. The rocks occurring to the north of CSZ have suffered more complex metamorphic histories in comparison to the southern part. Integrating the results of the present field and metamorphic studies with the earlier investigations and available geochronological data it has been suggested that the CSZ could represent a suture zone between two different continental blocks that underwent distinct metamorphic evolution.

7 illus, 3 tables, 47 ref

013345   Jin S G;Park P H (Space Geodesy Res Grp, Korea Astr and Space Sci Inst, Daejeon 305-348, South Korea, Email: sgjin@kasi.re.kr) : A new precision improvement in zenith tropospheric delay estimation by GPS. Curr Sci 2005, 89(6), 997-1000.

Accurate GPS-derived ZTD (zenith tropospheric delay) plays a key role in near real-time weather forecasting, especially in improving the precision of Numerical Weather-Prediction (NWP) models. However, ZTD is usually estimated under the assumption that all the GPS measurements, carrier phases or pseudo-ranges, have the same accuracy. These assumptions are unrealistic, which will inevitably degrade the precision of ZTD estimation. Communication aims to further improve the precision of ZTD estimation by stochastic modelling. The results show that the precision of GPS-derived ZTD can be obviously improved using a suitable stochastic model for GPS measurements. The stochastic model using satellite elevation angle-based cosine function is better than other investigated stochastic models. This improvement of ZTD estimation is certainly critical for reliable NWP and other tropospheric delay corrections.

2 illus, 18 ref

013344   Gupta V (NO, Wadia Inst of Himalayan Geol, Dehra Dun-248 001, Email: vgupta_wihg@yahoo.com) : Application of lichenometry to slided materials in the higher Himalayan landslide zone. Curr Sci 2005, 89(6), 1032-6.

Lichen-based study involving the measurement of per cent cover of lichens on slided materials in the Pawari landslide zone located in the Higher Himalaya has been described. This has been correlated with the indicators showing movement of deposits and activity of the slide. It has been well documented that in a slided mass, boulders containing more lichen cover are stable in the present climatic scenario or have moved least compared to the ones showing lesser lichen cover. Slopes covered with more or less fresh rock boulders and pebbles in the slide zone indicate an active part within the slided mass. Study can be used as an indirect method to assess the differential movement of slope within the slide mass.

7 illus, 15 ref

013343   Guha D;Das S;Srikarni C;Chakraborty S K (Geol Surv STOPWORD India, Operation Gujaral, Gandhinagar-382 093, Email: dipayanguha@vsnl.net) : Alkali basalt of Kachchh: its implication in the tectonic framework of mesozoic of Western India. J Geol Soc India 2005, 66(5), 599-608.

Field evidences in Kachchh show that alkali basalts occur as flows over Mesozoic sediments. The lop parts of Mesozoic Bhuj Sandstone often carry scoria and lapilli related to alkali basalt magmatism indicating that alkali magmatism and sedimentation went side by side. Tholeiite flows occur as blanket over bom Mesozoic sediments and alkali basalt bodies. Evidences are provided to show that alkali basalt magmatism in Kachchh was not only an earlier episode than tholeiite emplacement; it also predates the closing of Kachchh Mesozoic basin and seems to support a protracted period of Deccan magmatism (70 - 60 Ma). The study also shows that huge concentration of alkali basalt in the western Kachchh mainland is associated to a zone of transtension related to the rifting of Kachchh basin. Alkali basalt bodies and whole of Mesozoic sequence were affected by reverse faults related to closure of Kachchh basin with development of series of hanging wall anticlinal and footwall synclinal structures.

7 illus, 4 tables, 19 ref

013342   Ghosh G;Saha D (Dep STOPWORD Geol, Presidency Coll, Kolkata-700 073, Email: gautam_0262@rediffmail.com) : Kinematics of large scale asymmetric folds and associated smaller scale brittle-ductile structures in the proterozoic somnur formation, Pranhita-Godavari valley, South India. J Earth Syst Sci 2005, 114(2), 125-42.

Development of structural elements and finite strain data are analysed to constrain kinematics of folds and faults at various scales within a Proterozoic fold-and-thrust belt in Pranhita-Godavari basin, south India. The first order structures in this belt are interpreted as large scale buckle folds above a subsurface decollement emphasizing the importance of detachment folding in thin skinned deformation of a sedimentary prism lying above a gneissic basement. That the folds have developed through fixed-hinge buckling is constrained by the nature of variation of mesoscopic fabric over large folds and finite strain data. Relatively low, irrotational flattening strain (X:Z - 3.1-4.8, k <60> 1) are associated with zones of near upright early mesoscopic folds and cleavage, whereas large flattening strain (X:Z - 3.9-7.3, k <60> 1) involving noncoaxiality are linked to domains of asymmetric, later inclined folds, faults and intense cleavage on the hanging wall of thrusts on the flanks of large folds. In the latter case, the bulk strain can be factorized to components of pure shear and simple shear with a maximum shearing strain of 3. The work reiterates the importance of analysis of minor structures in conjunction with strain data to unravel the kinematic history of fold-and-thrust belts developed at shallow crustal level.

12 illus, 3 tables, 50 ref

013341   Ghose N C;Mukherjee D;Chatterjee N (Dep STOPWORD Geol, Patna Univ, Patna-800 005, Email: ghosencprof@rediffmail.com) : Plume generated mesoproterozoic mafic-ultramafic magmatism in the Chotanagpur mobile belt of Eastren Indian shield margin. J Geol Soc India 2005, 66(6), 725-40.

The Chotanagpur gneiss-granulite complex (CGGC) -a mobile bell north of the Archaean Signbhum cratonic nucleus and contiguous orogenic belt with the Singhbhum Proterozoic basin, is a vast tract of high-grade rocks and gneisses with enclaves of granulite and metasedimentary rocks, and intrusive granites of Proterozoic age. Pervasive intrusions of man lie-derived rocks of varied composition ranging from mafic-ultramafic, sodic-ultrapotassic alkaline rocks, massif anorthosite 10 younger tholeiitic basalts (Rajmahal) and dolerite at different geological periods ranging from Late Paleoproterozoic to Early Tertiary, give evidence of an active mantle in the prolonged history of evolution of this mobile belt. The present study is limited to metamorphosed mafic ultramafic rocks at the eastern sector of CGGC. The mafic-ultramafic suite is represented by amphiboliie, basic granulite and hornblendite. Compositions of the primary amphibole in these rocks range from hornblende to pargasitic hornblende, and pargasitic hornblende, and plagioclase from An₄₉ to An₅₉. Positive correlation of Mg# between clinopyroxene and hornblende, and clinopyroxene and orthopyroxene, indicating that the Fe-Mg exchange K_D is constant between the ferromagnesian minerals, and the rocks to have attained equilibrium conditions of metamorphism. Calculated post-peak metamorphic equilibrium pressures and temperatures are 3.8-5.4 kb and 643-781°C, similar to conditions in the surrounding country rocks. Chemically, the metabasic rocks studied are associated with the Bengal anorthosite massif at Saltora and have been grouped into low-Ti and high-Ti tholeiites. The former shows similarity with transitional basalts derived from T-MORB, while the latter is rich in incompatible elements and shows affinity with basalts derived from E-MORB or from recycled mantle fed by subducted oceanic crust. The nepheline normative ultramafic rock is the most depleted in incompatible elements and shows similarity in trace element contents with MORB. All these rocks show variable crustal contamination. Nevertheless, the bulk chemical compositions of the low-Ti rocks preserve evidence of low-pressure fractional crystallisation involving olivine, plagioclase and clinopyroxene. The intra-cratonic Mesoproterozoic bi-modal (tholeiitic-alkaline) magmatism in CGGC is analogous to Phanerozoic magma generation (Rajmahal tholeiites-ullrapotassic mafic-ultramafic intnisions in the Gondwana basins) in a rift setting (Damodar graben/shield margin faults) accompanied with crustal thinning. The trace element geochemistry of mafic-ultramafic rocks gives evidence of plume-generated magmatism in the Eastern Indian Shield margin during Mesoproterozoic lime, which is correlatable with the global thermal event in the Precambrian shields.

12 illus, 5 tables, 50 ref