000230   Ravi Kumar R;Srinivas G;Shadaksharaswamy N; Somashekar R K (Energy Economy and Environmental Consultants, , Indiranagar I stage, Bangalore-560 038) : Water quality index (WQI) for quarries and crushing sites in Bangalore district, Karnataka. Asian J Microbiol Biotechnol envir Sci 2000, 2(1-2), 29-33.

Quality of water around quarries and crushing sites of Bangalore District was assessed by calculating water quality index after considering seven water qualigy parameters. The indices ranged from 57.5 to 88.8 in surface water and 62.4 to 96.3 for groundwater samples. This indicates slight to moderate pollution and, that water may be used for drinking only after treatment. The variation of these parameters is perhaps due to deposition of dust and geochemistry of rocks. An attempt has been made to discern the sources of distortion in water quality (either pollutional or geological) after comparing the parametric ratios.

11 ref

000229   Rathore L S;Singh K K;Saseendran S A;Baxla A K (National Centre for Medium Range Weather Forecasting, Deptt of Science, , Mausam Bhawan, Lodi Road, New Delhi-110 003) : Modelling the impact of climate change of rice production in India. Mausam 2001, 52(1), 263-74.

CERES-Rice crop simulation model, calibrated and validated for the varieties PR 106 in NW India, IR 36 in central India and Jaya in south India, is used for analysing the effect of climate change on rice productivity in the country. Plausible climate change scenario for the Indian subcontinent as expected by the middle of the next century taking into account the projected emissions of greenhouse gases and sulphate aerosols, in a coupled atmosphere-ocean model experiment performed at Deutsches Klimarechenzentrum, Germany, is adopted for the study. The adopted scenario represented an increase in monsoon seasonal mean surface temperature of the order of about 1.5°C over the south India and 1°C over northwest and central India in the decade 2040-49 with respect to the 1980s and an increase in rainfall of the order to 2 mm per day over south India while the simulated decrease of the order about -1 mm an d-1.5 mm over northwest and central India respectively. The IPCC Business-as-usual scenario projection of plant usable concentration of CO₂ about 460 PPM by the middle of the next century are also used in the crop model simulation (CERES - Rice V3 Model).

43 ref

000228   Rastogi B K;Gupta H K;Mandal P;Satnarayana H V S;Kousalya M;Raghavan R;Jain R;Sarma A N S;Kumar N;Satyamurty C (NO, Natl Geophys Res Inst, Post Bag 724, Hyderabad-500 007) : Deadliest stable continental region earthquake occurred near Bhuj on 26 January 2001. J Seismol 2001, 5(4), 609-15.

Large destructive earthquake occurred on 26 January 2001 in the region of Kutch, Gujarat, In Western India, with magnitude Mw 7.7. The earthquake caused very heavy damage and a large number of casualties with more than 20,000 deaths. A preliminary study of ground deformation, damage pattern and aftershock distribution is presented.

15 ref

000227   Raman C V;Reddy K S N (Department of Geology, Andhra University, Visakhapatnam-530 003) : Sediment dispersal pattern off the Mahanadi - Nagavali continental shelf, northwest Bay of Bengal. J Geol Soc India 2001, 58(2), 123-33.

Textural distribution patterns of seafloor sediments from the Mahanadi - Nagavali shelf, northwest Bay of Bengal, are used to evolve a model for the regional sediment - dispersal system. Mean size trends, standard deviation, skewness and correlation of negative skewness with silt/clay ratios reveal certain patterns, each being specific to an area (s) of shelf. Sediment distribution patterns show that the near shore environment is occupied by sand and clayey sand, while the inner and middle shelf regions are covered by sandy silt, silty calcareous sand, silty clay, silty sand and sand-silt-clay. The outer shelf is largely covered by clayey silt. Relict carbonate deposits are preserved on the outer shelf at <126> 100 m off Rushikulya to Baruva. Palimpsest sediments cover the Sonapurapeta - Bavanapadu shelf at depths of 0-60 m. Mud dispersal in the study area offshore is caused by transport components along and across the shelf. The Mahanadi-Devi River system is the principal source of sediment for the Mahanadi-Nagavali shelf. The Nagavali and Vamsadhara rivers are a minor source of sediment towards the southern part of the shelf, and their detrital inputs are largely deposited on the shelf adjacent to the river mouths. Sediments in the study area are transported and advected southward (bottom nepheloid layers?).

31 ref

000226   Rajeevan M (India Meteorological Department, , Pune-411 005) : Interactions among deep convection, sea surface temperature and radiation in the Asian monsoon region. Mausam 2001, 52(1), 83-96.

Climatic interactions among deeep convection, sea surface temperature and radiation in the Asian monsoon region have been examined using various satellite-derived data sets of the period 1983-90. Annual average Frequency of Deep Convection (FDC) is maximum over the equatorial east Indian ocean and adjoining west Pacific and Indonesian region. Maximum FDC zone shifts to Bay of Bengal during the monsoon (June-September) season. There is a weak relationship between the variations in FDC and SST in the Indian Ocean. Deep convective activity was suppressed over most of the tropical Indian ocean during El Nino of 1987 in spite of warmer SSTs. The pattern of interannual variation between FDC and SST behaves differently in the Indian ocean basin as compared to the Pacific ocean basin. Deep convective clouds interact with radiation very effectively in the Asian monsoon region to cause large net negative cloud radiative forcing. Variation in FDC explains more than 70% of the variation in surface shortwave cloud radiative forcing (SWCRF) and long wave cloud radiative forcing (LWCRF) in the atmosphere. On inter-annual scale, warmer SSTs may not necessarily increase deep convection in the Indian ocean. However, the inter-annual variation of deep convective clouds influences significantly the radiative budget of the surface-atmosphere system in the Asian monsoon region.

43 ref

000225   Rajan D;Mitra A K;Rizvi S R H;Paliwal R K; Bohra A K;Bhatia V B (NO, Natl Ctr Medium Range Weather Forecasting, Lodhi Rd., New Delhi-110 003) : Impact of satellite derived moisture in a global numerical weather prediction model. Atmosfera 2001, 14(4), 203-09.

In recent years space instruments and remote sensing tools are allowing us to look at the Earth with new eyes; they have extended the scope of vision. India has the world's most gigantic monsoon system which is extremely important for the Indian agriculture. India gets most of its rain during four months (June to September) of the monsoon season. In July there is highest number of tropical disturbances in the Indian oceanic region. During the month of July 1996, two low pressures and one depression formed over Indian region. The study aims to derive the moisture profile for the period July 1996, by using remote sensing technique and their impact on the analysis-forecast system. The inclusion of satellite derived moisture in the numerical weather prediction (NWP) model results : the weakening monsoon flow pattern near Somalia region, the reduction of wind speeds in the south Bay of Bengal, the formation of a trough in the west coast of India, and the realistic rainfall prediction over the Orissa and Andhra Pradesh region, etc. All these effects are in contrast to the existing control and could help in better prediction of rainfall and flow pattern during the monsoon season.

13 ref

000224   Raj P (Ground Water Department, Andhra Pradesh State, Hyderabad) : Trend analysis of groundwater fluctuations in a typical groundwater year in weathered and fractured rock aquifers in parts of Andhra Pradesh. J Geol Soc India 2001, 58(1), 5-13.

High frequency (i.e., continuous record set at 6 hours interval) groundwater level monitoring was started in early 1998 in Andhra Pradesh under the National Hydrology Project. Well hydrographs in the hardrock terrain during the monsoon period show erratic rising trends interspersed with flatter or declining trends, indicating that monsoon recharge occurs in short bursts. The hydrographs during the non-monsoon period show linear recession limbs. However, some hydrographs exhibit a slow-down in rate of recession as the non-monsoon period advances, thereby causing the trend to become curvilinear and fitting into exponential or geometric curve. Curvilinear trends are due to the effect of a complex aquifer system that exhibits double porosity, boundary effects as well as anisotropic and heterogeneous behaviour. Coefficients of recession (R²) in recession limbs of all the hydrographs are nearly equal to 1, indicating that there are no irregular abstraction rates or irregular surges of recharge in non-monsoon period, which would help in predicting non-monsoon water levels. Diurnal fluctuations within both the rising limbs and recession limbs, do not show any appreciable difference except at the precise time of recharge surge./ Exponential recession coefficient of the hydrograph at the end of recession period, when only the aquifer parameters influence the data i.e. the decline in water level, indicate approximate spacific yield values of 0.009 to 0.038.

16 ref

000223   Prasad L K;Ghosh S K (DWMR, Walmi Complex, , Phulwari Sharif, Patna-801 505) : Nature and formation of clay minerals in soils of east Godavari district of Andhra Pradesh. Clay Res 2000, 19(2), 57-67.

Four different parent materials stretched over more than sevently five per cent of total area of East Godavari district produced a mosaic of soils with varying clay mineralogical composition. The alluvium and kateru traps are dominated by smectite followed by mixed layer minerals and kaolinite. Na and K feldspars rich crystallines and metamorphic rocks and red sandstones yielded kaolinite followed by mica and traces of smectites. Montmorillonite formation occcurred mainly from Ca and Na feldspars under basic ionic environment as the parent material is basaltic in origin and whatever clay mica and kaolinite present in the profiles studied were due to partial hydrolysis and weathering of 2:1 silicate minerals, respectively. Kaolinite is dominant in soils developed from crystallines and sandstones and formed through the pathway of mica weathering (K-feldspars→clay mica→kaolinite). Prominent mineral peaks were found which corresponds to the minerals represebnting 7, 8 and 9th stages of Jackson's weathering sequence for soils developed from alluvium and kateru traps. The other peaks respresent 7th and 10th stages of the weathering sequence for soils developed from crystallines and red sandstones.

17 ref

000222   Pal P K;Thapliyal P K;Dwavedi A K (Atmospheric Sciences Division, Space Applications Centre, , Ahmedabad-380 053) : Regional climate changes due to double CO₂ simulation by CCM3. Mausam 2001, 52(1), 221-8.

An equilibrium experiment has been conducted with CCM3 climate model in which the amount of CO₂ in the model atmosphere is doubled and the differences in resulting climate has been examined. The results show that there is an overall decrease in outgoing longwave radiation indicating the possible increase in cloudiness. The total rainfall may not change significantly but the temporal and spatial distributions over India are likely to change as observed in past long term trends.

000221   Owen L A;Gualtier L;Finkel R C;Caffee M W; Benn D I;Sharma M C (Dept Earth Sci, Univ Calif Riverside, Riverside, CA 92521, USA) : Cosmogenic radionuclide dating of glacial landforms in the Lahul Hamalaya, northern India - defining the timing of late quaternary glaciation. J Quaternary Sci 2001, 16(6), 555-63.

Timing of glaciation in the Lahul Himalaya of northern India was ascertained using the concentrations of cosmogenic Be-10 and Al-26 from boulders on moraines and drumlins, and from glacially polished bedrock surfaces. Five glacial stages were identified: Sonapani I and II, Kulti, Batal and Chandra. Of these, cosmogenic exposure ages were obtained on samples representative of the Batal and Kulti glacial cycles. Stratigraphical relationships indicate that the Sonapani I and II are younger. No age was obtained for the Chandra glacial advance. Batal Glacial Stage deposits are found throughout the valley, indicating the presence of an extensive valley glacial system. During the Kulti stage, glaciers advanced ca. 10 km beyond their current positions. Moraines produced during the Batal stage, ca. 12-15.5 ka, are coeval with the Northern Hemisphere Late-glacial Interstadial (Bolling/Allerod). Deglaciation of the Batal Glacial stage was completed by ca. 12 ka and was followed by the Kulti glacial stage during the early Holocene, at ca. 10-11.4 ka. On millennial time-scales, glacier oscillations in the Lahul Himalaya apparently reflect periods of positive mass-balance coincident with times of increased insolation. During these periods the South Asian summer monsoon strengthened and/or extended its influence further north and west, thereby enhancing high-altitude summer snowfall.

50 ref

000220   Mukherjee P K;Pal T;Sengupta S;Shome S (Central Petrological Laboratory, Geological Survey of India, , 15, Kyd Street, Kolkata-700 016) : Arsenic rich phases in aquifer sediments from southern West Bengal. J Geol Soc India 2001, 58(2), 173-6.

^ssc11 ref

000219   Mishra S;Rajaguru S N (NO, Deccan College, Pune-411 006) : Late quaternary palaeoclimates of western India - a geoarchaeological approach. Mausam 2001, 52(1), 285-96.

Western India comprises parts of the states of Rajasthan, Gujarat and Maharashtra. This region has varied climate and landscape. Northwestern Rajasthan is an area of internal drainage, with dunes, playas and rocky pediments. The Luni, Sabarmati and Mahi basins to the south of this zone show the inflence of both aeolian and fluvial processes. Aeolian landforms are absent in the narmada, Tapi, Godavari and Bhima basins and fluvial aggradation has alternated with erosion in response to climatic change. Dominance of semi-arid to arid climate throughout the Quaternary in the entire region has meant that Quaternary geological processes have been weak, preserving many features of the Tertiary in the present landscape. The variation in the geomorphic processes shaping the landscape and the complex links between geomorphic processes and climate mean that out understanding of palaeoclimates in western India is far from complete. Gives an overview of the Late Quaternary palaeoclimate of western India, based primarily on recent work by the authors in Rajasthan and Maharashtra. Some issues in the palaeoclimatic interpretation of the geological record are discussed. Signatures of Late Pleistocene aridity, fluctuating climate during the Pleistocene Holocene transitional period, early Holocene humid climate and increased aridity from the middle Holocene onwards are reflected in different ways in the different landscape settings.

55 ref

000218   Maheskumar R S;Devara P C S;Pandithurai G;Raj P E;Dani K K (Phys Meteorol and Aerol Div, Indian Inst Trop Meterorol, Dr Homi Bhabha Road, Pune-411 008) : Winter aerosol optical depths over a tropical urban station. Atmosfera 2001, 14(4), 159-69.

At Pune (18 degrees 32'N, 73 degrees 51'E, 559 in AMSL), a tropical urban station in India, aerosol characteristics during the winter season exhibit unique features such as low-level inversions and dust haze formation during morning hours. Moreover, this station experiences abundance of sub-micron sized aerosols due to passage of continental air mass during winter. With a view to examine these winter aerosol properties, in detail, the PC-based high spectral resolution radiometer has been operated in the 0.4-0.7 mum wavelength region at the Indian Institute of Tropical Meteorology, Pune, India. The details of the spectroradiometer together with the data acquisition and analysis procedures have been briefly described. Results obtained from the observations carried out on 75 cloud-free days during the successive winters of 1993-94, 1994-95 and 1995-96 have been presented and discussed in the light of local meteorological and environmental conditions. Of the three winters considered for the study, aerosol optical depths during the 1995-96 winter indicate greater values and forenoon aerosol size spectra exhibit bimodal distribution suggesting the dominant combined influence of transport of continental aerosols and trapping of surface-generated aerosols due to close-to-ground inversion during the season over the experimental station.

12 ref

000217   Madhavaraju J;Ramasamy S (Sedimentology Lab, Department of Geology, School of Earth and Atmosphe, University of Madras, Guindy Campus, Chennai-600 025) : Clay mineral assemblages and rare earth element distribution in the sediments of Ariyalur group, Tiruchirapalli district, Tamil Nadu - implication for paleoclimate. J Geol Soc India 2001, 58(1), 69-77.

Illite and smectite are the major clay minerals, whereas kaolinite and chlorite are present in small amounts in the sedimentary rocks of Ariyalur Group. The samples belonging to Ariyalur Group exhibit LREE enriched and flat HREE patterns. These samples show high ratios of ∑LREE/∑HREE (7.65 to 19.42) which indicate that these sediments were derived from the felsic source rocks. The persistence of uniform REE patterns for the clastic samples of four formations of Ariyalur Group distinctly implies a homogenous nature of the source rocks. The Sillakkudi and Kallankurichchi Formations (Campanian - early Maastrichtian) exhibit high content of illite which indicate that the sediments were derived from pre-existing rocks (granites and gneiss), subjected to physical weathering in a temperate climate. A sudden change in illite content was noticed in Ottakkovil Formation, which probably points out a change of climate from cold to warm during middle Maastrichtian. The abundance of pedogenic smectite in the Kallamedu Formation suggests warm climate with dry/wet cycles.

53 ref

000216   Lal M;Singh S K (Centre for Atmospheric Sciences, Indian Institute of Technology, New Delhi-110 016) : Global warming and monsoon climate. Mausam 2001, 52(1), 245-62.

Response of the Asian summer monsoon to transient increases of greenhouse gases (GHGs) and sulfate aerosols in the Earth's atmosphere is examined using the data generated in numerical experiments with available coupled atmosphere-ocean global climate models (A-O GCMs). A comparison of observed and model-simulated trends in monthly mean near-surface temperature and rainfall over the region provides evidence of skill of the A-O GCMs in simulating the regional climatology. The potential role of the sulfate aerosols in obscuring the GHG- induced warming over the Indian subcontinent is discussed. Even though the simulated total seasonal rainfall over the Indian subcontinent during summer monsoon season is underestimated in most of the A-O GCMs, the year to year variability in simulated monsoon rainfall over the study region is found to be in fair agreement with the observed climatology.

11 ref

000215   Kulkarni J R;Mujumdar M;Gharge S P;Satyan V; Pant G B (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Impact of solar variability on the low frequency variability of the Indian summer monsoon. Mausam 2001, 52(1), 67-82.

Earlier investigations into the epochal behaviour of fluctuations in All India Summer Monsoon Rainfall (AISMR) have indicated the existence of a Low Frequency Mode (LFM) in the 60-70 years range. One of the probable sources of this variability may be due to changes in solar irradiance. To investigate this, time series of 128-year solar irradiance data from 1871-1998 has been examined. The Wavelet Transform (WT) method is applied to extract the LFM from these time series, which show a very good correspondence. A case study has been carried out to test the sensitivity of AISMR to solar irradiance. The General Circulation Model (GCM) of the center for Ocean-Land-Atmosphere (COLA) has been integrated in the control run (using the climatological value of solar constant i.e. 1365 Wm^-2) and in the enhanced solar constant condition (enhanced by 10 Wm²) for summer monsoon season of 1986. The study shows that the large scale atmospheric circulation over the Indian region, in the enhanced solar constant scenario is favourable to good monsoon activity. A conceptual model for the impact of solar irradiance on the AISMR at LFM is also suggested.

52 ref

000214   Krishnamurthy V;Shukla J (Center for Ocean-Land-Atmosphere Studies, Institute of Global Environment and Society, Inc. 4041 Powder Mill Road, Suite 302, Calverton, MD 20705) : Observed and model simulated interannual variability of the Indian monsoon. Mausam 2001, 52(1), 133-50.

Center for Ocean-Land-Atmosphere (COLA) general circulation model has been integrated seven times with observed global sea surface temperature (SST) for the years 1979-98. The model-simulated annual cycle, the seasonal mean and the interannual variability of the summer monsoon rainfall and circulation over the Indian region are compared with the corresponding observations. It is found that, although this model ahss shown remarkable success in simulating the local and global response of tropical SST anomalies, the model shows poor skill in simulating the interannual variability of monsoon rainfall over India. While it is true that the correlation between the observed tropical Pacific SST and the Indian summer monsoon rainfall for the most recent 20 years itself is considerably lower than that for other 20 years periods in the past, it is likely that the model's inability to stimulate rainfall variability over India is largely related to the systematic errors of the model in simulating the climatological mean monsoon circulation and rainfall, especially over the oceanic regions.

16 ref

000213   Karbassi A R;Shankar R;Manjunatha B R (NO, Institute of Environmental Studies, Tehran University, P.O. Box 14155-6135, Tehran) : Geochemistry of shelf sediments off Mulki on the southwestern coast of India and their palaeoenvironmental significance. J Geol Soc India 2001, 58(1), 37-44.

Geochemical and textural variations of these sediments suggest changes in the depositional environments: Sediments of the lower zone were deposited in a marshy environment when the core site was close to the shore during the late Pleistocene low stand of sea level. The late Quaternary sea level rise led to a shift in the depositional environment - from marsh to a still stand beach environment-when silty sands were deposited. Although the core site has been in the shelf since the beginning of Holocene, there has not been much sedimentation not only because of the negligible quantity of sediment supplied by the small west-flowing rivers but also due to the rapid rise in sea level during early Holocene. The reconstructed depositional history of the core is in consonance with the recently proposed sea level curve for the western continental margin of India.

28 ref

000212   Joshi P C;Simon B;Thapliyal P K (Atmospaheric Sciences Division, Space Applications Centre, , Ahmedabad-380 015) : Satellite estimated water vapour in relation to Asian monsoon circulation. Mausam 2001, 52(1), 109-16.

Water vapour plays a crucial role in various exchange and transport processes in the atmosphere and its knowledge in the tropics is extremely important for input to various global circulation models. The vast oceans of earth's surface provide a large source of moisture and continuously modify the thermodynamics of the atmosphere through latent heat flux and condensational heating. In the tropics, especially in the Indian ocean the water vapour is highly heterogeneous in nature, and is one of the parameters which is responsible for cloud formation, associated with tropical systems like monsoon flows, depression, cyclones etc. Reviews the various informations available from deferent geostationary and polar orbiting satellites about water vapour affecting the southwest monsoon region around the Indian Ocean and Indian subcontinent. The temperature and moisture data from TIROS operational vertical sounder (TOVS) and INSAT-2E water vapour channel are examined to study water vapour distribution. Their usefulness in characterizing the Asian south-west (SW) monsoon circulation is focused. The Western Indian ocean showed an increase in mid-tropospheric moisture (700-500 hPa) over about 8 to 10 days prior to the onset over Kerala coast. NOAA/TOVS layer temperature and humidity is used to extrapolate the humidity profile at standard pressure levels. It is also used to compute latent and sensible heat flux.

25 ref

000211   Joshi A (Dept. Earth Sci, Kurukshetra University, Kurukshetra-136 119) : Strong motion envelope modelling of the source of the Chamoli earthquake of March 28, 1999 in the Garhwal Himalaya, India. J Seismol 2001, 5(4), 499-518.

Chamoli earthquake of March 28, 1999 was recorded at 11 different stations of a strong motion array installed in the epicentral region. The maximum peak ground acceleration (353 cm/s(2)) was recorded at an accelerograph located at Gopeshwar. The data from eleven stations has been used for comparison with the simulated acceleration envelopes due to a model of the rupture responsible for this earthquake. For simulation of acceleration envelope the method of Midorikawa (1993) has been modified for its applicability to Himalayan region. This method has earlier been used by Joshi and Patel (1997) and Joshi (1999) for the study of Uttarkashi earthquake of 20th Oct, 1991. The same method has been used for study of Chamoli earthquake. Layered earth crust has been introduced in place of homogeneous one in this method. The model of rupture is placed at a depth of 12 km below the Munsiari thrust for modelling Chamoli earthquake. Peak ground acceleration was calculated from simulated acceleration envelope using layered as well as homogeneous earth crust. For the rupture placed in a layered crust model peak ground acceleration of order 312 cm/s(2) was simulated at Gopeshwar which is quite close to actually recorded value. The comparison of peak ground acceleration values in terms of root mean square error at eleven stations suggests that the root mean square error is reduced by inclusion of a layered earth crust in place of homogeneous earth crust.

64 ref

000210   Jassal H S;Gill G S;Sidhu P S (Department of Soils, Punjab Agricultural University, Ludhiana-141 004) : Clay mineralogy and major element geochemistry of the upper Siwalik sequence of Punjab, Northwestern Himalaya. J Geol Soc India 2001, 58(2), 113-22.

X-ray diffraction and major element analyses of the upper Siwalik rocks of Punjab were carried out to assess the clay mineral composition of the rocks. The clay mineral assemblages comprise illite, smectite, kaolinite, chlorite and mixed layer phyllosilicates. The SiO₂/Al₂O₃ and SiO₂/R₂O₃ molecular ratios of the clays range between 3.86 and 6.60, and 2.94 and 5.37 respectively, suggesting dominance of 2:1 type clay minerals in these rocks. Inheritence and transformation were recognized as the chief processes responsible for genesis of these clay minerals. The clay mineral assemblages suggest their formation under moderate chemical weathering conditions in cool to temperate climate.

35 ref

000209   Jain C K;Sharma M K (NO, Natl Inst Hydrol, Roorkee-247 667) : Distribution of trace metals in the Hindon River system, India. J Hydrol 2001, 253(1-4), 81-90.

Distribution of trace metals (Cu, Zn, Fe, Mn, Cd, Cr, Pb, and Ni) in water, suspended and bed sediments of the River Hindon, a highly polluted river in western Uttar Pradesh (India) has been studied. The river is polluted by municipal, industrial and agricultural effluents, and flows through the city of Saharanpur, Muzaffarnagar and Ghaziabad districts. The heavy metal concentrations in water were observed to depend largely on the Sediment analysis indicates that the large amount of heavy metals is associated with organic matter, the fine-grained sediment fraction and Fe/Mn hydrous oxides. A high positive correlation of most of the metal ions in sediments with iron, manganese and organic matter indicate that these constituents play a major role in transport of metal ions. The heavy metal concentrations generally increased with the decreasing particle size of the sediments. Lower metal concentrations in bed sediments during post-monsoon season established that monsoon had a slight effect on status of metals in sediments by causing renewal and mobilization of metals from the sediments.

^aabstr48 ref

000208   Jagadheesha D;Ramesh R (Physical Research Laboratory, , Ahmedabad-380 009) : Past monsoons - a review of proxy data and modelling. Mausam 2001, 52(1), 275-84.

Recent modelling studies have given insight into the role of internal feedback processes among components of the climate system on the evolution of monsoon strength since the Last Glacial Maximum (21,000 years ago). Presents an overview of these modelling studies related to the summer monsoon over India and northern Africa. These studies indicate that the seasonal insolation changes alone do not explain the observed extent of hydrological changes during the early and middle Holocene over northern Africa. To simulate the extent of observed changes during this period incorporation of vegetation as an active component in climate models appears to be necessary. Over the Indian region, model results show that precipitation-soil moisture feedbacks play an important role in determining the response of the monsoon to changes in insolation and glacial-age surface boundary conditions. Indian monsoon strength from proxy records during the early and middle Holocene have also been used in conjunction with coupled ocean atmosphere general circulation model experiments to refute the suggestion that semi-permanent warm surface conditions prevailed over equatorial Pacific ocean from 11 to 5 ka.

41 ref

000207   Goswami B N;Manu Anna Thomas (Center for Atmospheric and Oceanic Sciences, Indian Institute of Science, Bangalore-560 012) : Decadal variations of hadley and walker circulations in the tropics. Mausam 2001, 52(1), 23-36.

Preliminary estimate of divergent Hadley and Walker circulation associated with inter-decadal variations in the tropics is made with 50-year reanalysis data and compared with their inter-annual counterparts. Interdecadal and inter-annual components are seperated using harmonic analysis and meridional and zonal mass flux stream functions are used to calculate the strength of Hadley and Walker circulations. The magnitude of inter-decadal Hadley and Walker circulation anomalies are shown to be comparable to those associated with dominant inter-annual variations. How superposition of inter-decadal and inter-annual divergent circulations may influence regional climate is discussed.

14 ref

000206   Gandhi M S;Seetharamaiah J;Bhanu Murty P (NO, Delta Studies Institute, Andhra University, Visakhapatnam-530 003) : An indigenous approach to low cost portable vibracoring in deltaic environments. J Geol Soc India 2001, 58(2), 176-8.

Simple but very effective and inexpensive indigenous method of vibracoring has been developed for acquisition of continuous cores in subaqueous environments at water depths of below 2m. The principal components are the following: 3.5 HP concrete vibrator, irrigation PVC tube, tripod and pulley. The entire system weighs 50 kg and approximately costs about Rs. 25,000/-. This system was operated successfully in the transitional sedimentary environments of the East Coast deltas by collecting around 100 cores averaging to 2 m in length. Sediments ranging from clay to coarse sand have been recovered using this system. Percentage of recovery was usually 60 to 100 and distortion of delicate sedimentary structures was generally minor.

^ssc

000205   Deo A A;Salvekar P S;Behera S K (NO, Indiana Institute of Tropical Meteorology, Pune-411 008) : Oceanic response to cyclone moving in different directions over Indian seas using IRG model. Mausam 2001, 52(1), 163-74.

IITM Reduced Gravity (IRG) ocean model is employed to investigate the influence of tropical cyclone moving in different directions in Indian Seas. Some of the observed storm tracks in the Arabian Sea and Bay of Bengal are considered which have northward and westward movement. Sensitivity study is carried out for initial position of the storm at (90°E, 10°N) and moving in different directions. For westward moving cyclones the right bias in the model upper-layer thickness deviation (ULTD) field disappears. In an another experiment of westward moving cyclone originating at different latitudes, the ocean response is found to be sensitive to the Coriolis parameter (↵). The surface currents as well as ULTD reduce, as ↵, increases. The amplitude and the wavelength of inertia gravity wave increase with decrease in <255>, in the wake of the cyclone. This study helps to determine the upwellig region arising due to movement of the cyclone.

10 ref

000204   Chandran P;Ray S K;Bhattacharyya T;Krishnan P;Pal D K (Division of Soil Resource Studies, National Bureau of Soil Survey and Land Use Planning, Amravati Road, Nagpur-440 010) : Clay minerals in two ferruginous soils of southern India. Clay Res 2000, 19(2), 77-85.

Two Benchmark ferruginous soils namely Jamkhandi and Palathurai have been taken for the study. In contrast to the general understanding, these ferruginous soils are calcareous and alkaline in nature. Layer silicates present in silt, coarse clay and fine clay fractions of these soils are also in sharp contrast to those of ferruginous soils reported earlier. Dominant presence of smectite in all the size fractions is very common alongwith mica. Kaolinite is present in Jamkhandi soils. Under the prevailing semi-arid environment neither such a huge amount of smectite nor kaolinite can be formed. These soils have suffered truncation as evident from their thin Ap horizon followed by Bt horizon of <62> 30 per cent clay, exposing a relatively unweathered soil formed in pre-Pliocene tropical humid climate. Smectite in fine clay fractions of Jamkhandi soils have both high and low charge density, whereas smectite in silt and coarse clay fractions have high charge. Mica present in silt and coarse clay fractions consists of more biotite than muscovite and it survived trpical weathering. In the present semi-arid climate biotite has weathered to high charge smectite. Aridity also induced the precipitation of calcium carbonate. High amount of weatherable minerals in ferruginous soils of southern India has distinct relevance in their water and K-management.

22 ref

000203   Casshyap S M;Bhardwaj B D;Raza M;Singh A;Khan A (Department of Geology, Aligarh Muslim University, Aligarh-202 002) : Barrier inlet and associated facies of shore zone: an example from Khardeola formation of lower vindhyan sequence in Chittaurgarh, Rajasthan. J Geol Soc India 2001, 58(2), 97-11.

Deposits are interpreted as originating within laterally migrating tidal inlets (barrier inlets), in which easterly oriented ebb currents were dominant, with intermittent influx of flood oriented and north or south directed longshore currents. Plane bedded to gently inclined units of quartzarenite are interpreted as beach foreshore (spit) deposits that occur in places, capping the barrier inlet sequence. A combination of barrier inlet migration and shoreline transgression resulted in a truncated and modified barrier island sequence, dominated by inlet fill sandstone that merges with or oversteps westward (landward) the interlayered, fine grained clastic lagoonal/tidal flat facies. The Khardeola sedimentation was terminated with the decline in sediment supply, rise in sea level and landward migration of shoreline, followed by deposition of the overlying algae dominated Bhagwanpura Limestone in a quiet, open shelf of transgressive phase.

000202   Borgaonkar H P;Pant G B (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Long-term climate variability over monsoon Asia as revealed by some proxy sources. Mausam 2001, 52(1), 9-22.

Studies on climate variability over the region of monsoon Asia mostly during the Quaternary. Based on various sources of proxy data have been reviewed. Increasing interest to understand the processes of monsoon system over the Asian region as well as the availability of data from variety of reliable proxy sources such as, ocean sediments, ice cores and historical documents have encouraged the palaeoclimatic studies in this region. Inferences drawn from the multiproxy sources indicate good association of glacial and inter-glacial phases with over all monsoon flow. Warm and wet periods are generally characterized by strong summer monsoon, where as, weak monsoonal activities were observed during cold and dry periods. All India monsoon rainfall since early 17th century based on dendroclimatic reconstructions shows trend-less nature with large interannual variability as seen in the instrumental record of recent century. Historical evidences over this region are a potential source of information on contemporary climate change.

12 ref

000201   Bisht B S;Rajasekaran P;Sinha R M (Atomic Minerals Directorate for Exploration and Research, Department o, , Begumpet, Hyderabad-500 016) : Fluid inclusion characteristics of unconformity-related uranium mineralisation, Lambapur-Peddagattu area, Andhra Pradesh. J Geol Soc India 2001, 58(1), 45-51.

Aqueous bi-phase fluid inclusions in quartz from mineralised vein, granite and pebbly quartzite have been studied to decipher physico-chemical conditions of the unconformity-related uranium mineralisation at Lambapur-Peddagattu area in the northern fringe of Cuddapah basin. Fluid inclusions in vein- and granitic- quartz show significant similarity in phase ratios and homogenisation temperatures, though they differ in the mode of origin. The main population of inclusions in vein quartz is of primary origin, while in granitic quartz it is of secondary origin. The size of fluid inclusions generally varies between 10μm to 20μm, with low gas to liquid ratios corresponding to high degree of fill (F=0.8 to 0.9). Inclusions in vein- and granitic- quartz homogenise to liquid phase between 140°C to 240°C (mode 150°C to 170°C) [T_H]. Similar temperature of homogenisation has been obtained in quartz of pebbly quartzite. The ice melting temperatures in vein quartz are in the range of -2°C to 10°C [T_M] equivalent to salinity of 1-14 wt% eNaCl and in granitic quartz these are in the range of -6°C to - 14°C [T_M] corresponding to salinity values of 10-18 wt ° eNaCl.

15 ref

000200   Bhattacharyya T;Srivastava P;Pal D K (Division of Soil Resource Studies, National Bureau of Soil Survey and Land Use Planning, Amravati Road, Nagpur-440 010) : In search of parental legacy for Gibbsite in soils. Clay Res 2000, 19(2), 69-75.

Proportions of kaolin and gibbsite are often inversely related in the soil profile and sum of these two minerals within the solum maintains a constancy which may suggest the formation of gibbsite at the expense of kaolin. Although the summation of clay K1/HIC and gibbsite in two representative Ultisols of north-east India show an apparent constancy, the transformation of kaolin to gibbsite is not feasible since kaolin is still in an intermediate stage as K1/HIV, which is yet to be fully transformed to kaolin. Such contrasting quantitative depth distribution of minerals is often observed even though there is no parental legacy between these minerals. The presence of both HIV and gibbsite in Ultisols indicates that the anti-gibbsites it is concluded that the formation of gibbsites at the expense of primary mineral in these Ultisols carries a signature of earlier alkaline pedochemical weathering. The occurrence of gibbsites should not therefore be considered as a conclusive evidence of advanced weathering conditions of soils.

22 ref

000199   Bhaskar Rao D V;Naidu C V;Srinivasa Rao B R (Department of Meteorology and Oceanography, Andhra University, Visakhapatnam) : Trends and fluctuations of the cyclonic systems overnorth Indian ocean. Mausam 2001, 52(1), 37-46.

Data of the monthly cyclone frequencies over North Indian Ocean for the period 1877-1998 has been analysed to study the long-term trends and fluctuations. Analysis has been made separately for depressions and cyclones for the pre-monsoon, monsoon and post-monsoon seasons along with the annual frequencies. The data was subjected to 11-year moving averages and the epochs of increasing and decreasing trends have been identified. A consistent decreasing trend after 1950s is a notable feature. The time series of the monthly cyclone frequency were passed through a high-pass filter to eliminate periods greater than 21 years and then subjected to spectrum analysis using Maximum Entropy Method to obtain dominant periodicities. Three significant periodicities at 2.2-2.8; 3.5-6.5 and 10-15 years have been identified which could be attributed to QBO, ENSO and decadal frequencies.

16 ref

000198   Beig G (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : Model evolution of the middle atmospheric palaeoenvironments. Mausam 2001, 52(1), 297-306.

Ice core air analysis has indicated a significant variation in the atmospheric contents of the greenhouse gases CO₂, CH₄ and N₂O from the last ice age to the present period. This may have contributed in altering the vertical distribution of temperature and composition of the atmosphere about which not much information is available. The two dimensional interactive model of radiation, dynamics and chemistry has been used to reconstruct the annual vertical distribution of thermal structure and trace gas concentrations of the middle atmosphere for the periods extending from last ice age to the present. For this purpose, ice core air data of the above mentioned forcing parameters are used as input to the model for different time frames including Mounder Maximum, Roman maximum, pre- industrial period and the last glacial period. Model results show that the considerable reduction in the greenhouse gas content for the last ice age has resulted in cooling of troposphere and a warming by about 10 to 15° K in the upper stratosphere as compared to present. The variation in temperature is closely related with the water vapour content. The percentage change in ozone concentration for the last glacial period is to a maximum of 50% near the poles in the upper stratosphere and about 10% in the tropics.

13 ref

000197   Becker B D;Slingo J M;Ferranti L;Molteni F (Centre for Global Atmospheric Modelling, Department of Meteorolgy, University of Reading, Trieste, Italy) : Seasonal predictability of the Indian summer monsoon: what role do land surface conditions play. Mausam 2001, 52(1), 175-90.

Anomalous springtime snow amount over Eurasia may provide long term memory to the climate system by affecting the land surface energy and moisture budgets. In turn the anomalous land surface conditions introduced by snow anomalies may influence monsoon variability. Results from a programme of seasonal forecast ensembles are used to address, specifically, the influence of western Eurasian land surface conditions on the variability and hence predictability of the Indian summer monsoon. The factors that are important for establishing spring time land surface conditions over western Eurasia, particularly snow amounts are also investigated. The results have shown that high snow amounts over western Eurasia are linked to La Nina, suggesting that the El-Nino/Southern Oscillation (ENSO) has in influence on the wintertime climate of Eurasia. The signature of these snow depth anomalies is carried through to the summer in terms of changes in soil wetness and surface temperatures. An ensemble of summer integrations with climatological sea surface temperature (SST) has been used to investigate the impact of these anomalous land surface conditions on monsoon variability. The results have shown that the monsoon circulation in substantially weakened in association with above normal snow amounts over western Eurasia, whilst All India Rainfall is slightly increased.

33 ref

000196   Bajpai U;Madhav Kumar;Shukla M;Anand-Prakash; Srivastava G P (NO, Birbal Sahni Institute of Palaecobotany, 53, University Road, Lucknow-226 007) : Nature and composition of pyrite framboids and organic substrate from degraded leaf cuticles of late tertiary sediments, Mahuadanr valley, Palamu, Bihar. Curr Sci 2001, 81(1), 102-6.

Detailed studies of pyrite framboids from degraded leaf cuticles have been carried out under scanning electron microscopy (SEM) and energy-dispersive X-ray analyser system (EDAX). The investigations indicate that framboidal pyrites form in the cavities and cell lumen of degraded leaves and other plant entities under reducing conditions. They occur in clusters and as solitary spherules. The elemental analyses indicate that the carbon, nitrogen, oxygen, phosphorus, iron and sulphur are the main constituents of framboids developed on the organic substrate. The morphological characters of bacterial colonies are generally retained during mineral uptake to form framboids.

2 illus, 1 table, 20 ref

000195   Bachiochi D;Jha B;Krishnamurti T N (NO, Florida State University, Department of Meteorology, Tallahassee FL 32306-452, USA) : Effect of Indian Ocean warming on the Indian monsoon: an atmospheric model study. Mausam 2001, 52(1), 151-62.

Results from an atmospheric modeling study using the Florida State University Global Spectral Model indicate that, in years such as 1997 when the Indian Ocean SSTs are large,, the Indian monsoon exhibits a typical behaviour. During that year, an extended shift of the tropical convergence zone towards the north played a role in the regional Hadley cell anomalies. The local warm boundary conditions in the northwestern Indian Ocean aided the high rainfall anomaly in Western India during the model simulations. The upper level structure, exhibited in terms of the global velocity potential is slightly shifted east for 1997, but with the correct sign,. This structure shows regions of convergence over Indonesia where severe drought had occurred. The performance of the model rainfall over the equatorial Indian Ocean was uncanny for most seasons studied. Overall, the model performed best over the oceanic regions.

24 ref

000194   Asnani G C (NO, Indian Institute of Tropical Meteorology, Pune-411 008) : El nino of 1997-1998 and Indian monsoon. Mausam 2001, 52(1), 57-66.

El-Nino of 1997-1998 was accompanied by severe global weather anomalies, which generated widespread interest at all levels in the world. As a result, united Nations General Assembly passed a resolution (52/200) urging International co-operation to reduce the adverse impact of El-Nino on human society and Environment. The El-Nino (Warm Phase) commenced around April - May 1997, reached peak intensity around December 1997 and ended around May 1998. La-Nina (Cold phase) started around this time, reached its peak in January 1999. Development and decay of the El-Nino are illustrated through SST, SOI and sea-water temperature below the sea-surface. Features during peak period of El-Nino are illustrated through SST, sea-level pressure, surface wind, OLR, and Walker Circulation. There is clear evidence of west-to-east propagation of OLR anomaly, 850 hPa zonal wind anomaly and sea-level pressure anomaly. SST anomaly pattern did not give strong evidence of this type of zonal progression. El-Nino is global in nature. El-Nino/La-Nina years during the 120-year period 1871 - 1990 are tabulated along with All India Summer Monsoon Rainfall (AISMR) amomalies. There is evidence of El-Nino years tending to become years of deficit rainfall and La-Nina years being years of excess rainfall over India. El-Nino/La-Nina events, which can be predicted 6-12 months in advance, can be used and are being used as part of the prediction formulae,

10 ref

000193   Anil Kumar;Gopalan K;Rao K R P;Nayak S S (NO, National Geophysical Research Institute, Uppal Road, Hyderabad-500 007) : Rb-Sr age of kimberlites and lamproites from eastern Dharwar craton, South India. J Geol Soc India 2001, 58(2), 135-41.

Acid-leached phlogopite Rb-Si isochron ages of the Kotakonda and Mudalbid kimberlites in the Narayanpet kimberlite field northwest of the Cuddapah basin, south India are 1085±14 and 1099±12 Ma, respectively. These concordant ages are much younger than the recently reported K-Ar and ⁴⁰Ar-³⁹Ar ages of 1363±48 and 1402±5 Ma, respectively for the former kimberlite, and support out earlier conclusion that the south Indian kimberlites erupted episodically close to 1090 Ma ago. Three lamproites - one each from Ramannapeta at the northeastern margin and Chelima and Zangamarajupalle within the Cuddapah basin - give distinctly different Rb-Sr ages of 1224±14, 1354±17 and 1070±22 Ma, respectively. While the Rb-Sr age of the Ramannapeta lamproite is also younger than an earlier reported K-Ar age of 1381±18 Ma, it is the same as that of many spatially close alkaline complexes like at Elchuru and Kunavaram. The ages for the Chelima and Zangamarajupalle rocks are only tentative, as these rocks contain a large secondary carbonate component with its Sr isotopic composition genetically unrelated to that of their phlogopites.

37 ref

023077   Vijay Gopal B;Sarma V N;Rambabu H V (National Geophysical Research Institute, , Hyderabad-500007) : Real time compensation for Aircraft induced noise during high resolutin airborne magnetic surveys. J Indian Geophys Union 2004, 8(3), 185-9.

Typical aeromagnetic survey requires fixing the magnetic sensor in a tail boom. For practical consideration, the tail boom can't be more than 10 to 15 feet long. As a consequence, there will by significant interfering magnetic field at the sensor due to the aircraft itself and also due to its maneuvers during flight. For high-resolution magnetic surveys, this interference is not acceptable. An instrument, callled Automatic Aeromagnetic Digital Compensator (AADC), makes it possible to remove these interferences in real time to a very good extent. However, in power latitudes cesium sensor enters into dead zone when aircraft maneuvers in certain directions, thereby making it impossible to obtain a single compensation solution that is valid for all four cardinal directions. Most of India falls into this category there by requiring careful calibration runs, which yield partial solutions for each cardinal direction. Proper combination of partial solutions is vital to get valid compensation solution. In this paper we desribe the AADC, it's calibration procedure and discuss the criteria for choosing partial solutions to arrive at combined solution. Also, actual calibration and compensation flight data is discussed.

3 illus, 1 table, 2 ref

023076   Sudhakar K S;Rao P R;Murthy I VR (Dep of Geophysics, Andhra Univ, Visakhapatnam-530 003) : Modified Werner deconvolution technique for inversion of magenetic anomalies of horziontal circular cylinders. J Indian Geophys Union 2004, 8(3), 179-83.

The classical Werner deconvolution technique tries to solve the body parameters of geophysical models by framing linear equations with the help of magenetic anomalies and their locations on a profile and solving them. In the present paper, a method is designed which uses position of point pairs with equal anomaly values, against the individual points in the Werner deconvolution technique. This method is presented with reference to the magnetic anomalies of a horizontal circular cylinder. On the profile, two position X₁ and X₂ for a chosen anomaly value ΔF are identified, and ΔF, X₁ and X₂ are used to frame linear equations and to calculate the depth to the center of the cylinder, its position and the dip of its effective magnetization.

3 illus, 2 tables, 10 ref

023075   Subrahmanyam M;Rao N V;Rao T K S P (Dep of Geophysics, Andhra Univ, Visakhapatnam-530 003) : Delineation of basement and Curie isotherm of Bay of Bengal from spectral analysis of magnetic data. J Indian Geophys Union 2004, 8(2), 107-23.

Fifteen total intensity magnetic profiles in the Bay of Bengal were processed in frequency domain. The profiles were divided into small overlapping segments for determining average depths from spectrum. High frequency component was resolved from the frequency spectrum and average depth to the deeper levels of Curie Isotherm was determined from low frequency range of spectrum. Appropriate depths to the upper marker (Magnetic basement) and lower surface (Curie Isotherm) along the length of the profile were tabulated. From these depths to the upper and lower markers of magnetic material, tentative models for crustal structure were prepared. Main geological features such as Continent Ocean Boundary,85°E ridge and 90°E ridge have been delineated distinctly from the inferred models. It has been observed that the depth to the basement varies between 8km and 10km along southern profiles and between 10km and 12km along northern profiles. The Curie Isotherm depth varies between 15km and 17km along southern profiles and between 20km and 22km northern profiles. The models also crustal dipping and thickening towards northern latitutedes.

17 illus, 2 tables, 29 ref

023074   Seshadri K S;Raj S S;Lal K B (Centralised Waste Mangement Facility, Bhabha Atomic Research Centre, Kalpakkam, Tamil Nadu-603102) : Spent ion exchange resin-its treatment from the point of view of safe disposal. Indian J envir Hlth 2003, 45(1), 21-4.

Ion exchange process is one of the treatment methods for radioactive waste. The resin becomes no longer useful after number of cycles of usage. At the same time the regenerated resin cannot be considered as non active waste for disposal. Hence it is felt necessary that the regenerated resin is treated in a fasion so as to result in a form which can be considered as inactive material. It is possible to convert this spent resin into multivalent ionic from which are generally non leachable, thus providing the necessary properties for meeting the disposal critera. Studies were carried out for the exchange of radioactive ions on these resins with ions like Al³⁺,Sn⁴⁺,Pb²⁺ and Fe³⁺ etc. The studies included leachability aspects, exchange with other active ions, thermal charcteristics, compressive strength of the cement blocks loaded with the resin etc. Studies indicated that the order of the stability of the resin with respect of properties like leachability, exchange properties etc. follow the trend as follows: Sn⁴⁺<62>Pb²⁺<62>Al³⁺<6 2>³⁺.

1 illus, 2 tables, 2 ref

023073   Roy M (Indian Institue of Geomagnetism, , Colaba Mumbai-400005) : Spectral characterctics of ULF waves obsreved simultaneously in space and on ground statins. J Indian Geophys Union 2003, 7(3), 167-71.

Ultra low frequency waves with periods between a few tens of minutes to a few minutes fall within the range of Ps-6 and Pc-5 micropulsation and observed as fluctuations in the magnetic fields in space as well as at the ground magnetic observations. Magnetic data recorded by satellites outside the magnetosphere (IMPSatellite), inside the magnetosphere (GOES-satellite) and at three ground stations have been analysed. The objective is to investigate how the waves generated in the interplanetary space get modified when they travel magnetosphere to the ground. It has been noticed that the low frequency part of the specturm of the ULF waves propagate to the surface of the earth with very little attenuation which indicated direct propagation as fast mode Alfven waves. However, the waves with higher frequencies (<62> lm Hz.) which are present in the IMP data, seem to propagate inside the magnetosphere as cavity modes. The frequencies of these waves can be explained in terms of over reflection at the magnetopause boundary as suggested by Mann, et.al (1999).

5 illus, 8 ref

023072   Roy K K;Dey S;Srivastava S;Biswas S (Dep of Geological Sci, Jadavpur Univ, Kolkata -700032) : What to trust in a Magnetotelluric model. J Indian Geophys Union 2004, 8(2), 157-11.

9 illus, tables, 16 ref

023071   Reddy P R;Chandrakala K (National Geophysical Institute, , Hyderabad-500007) : Seismicity in and around Ongole, Andhra Pradesh. J Indian Geophys Union 2004, 8(2), 143-6.

Ongole and its surrounding area had been subjected to structural deformation for the past 3000 Ma in plate tectonic history. The faults in this region are seismically active since a long time. This is supported by a confluence of faults system in the regin (including the conspicuous changes in the river courses) and a clear correlation between the fault pattern, the seismicity and the influence of Lithopheric dynamics. The continued seismicity of this area is attributable to a combination of neotectonic activity coupled with the effects of Indo-Antarctica breakup and periodical reactivation of faults, since geological past.

2 illus, 13 ref

023070   Rao V V;Raju J S;Rao B S P;Rao P K (Dep of Geo Engineering, Andhra Univ, Visakhapatnam-530003) : Bed rock investigation by seismic refraction method. J Indian Geophys Union 2004, 8(3), 223-8.

A high-rise RCC Bridge is under construction across the Krishna River on the downstream side of the Nagarjuna Sagar Dam, Nalgonda district of Andhra Pradesh. This bridge is constructed paralled to the old bridge on the upstream side that collapsed a few years ago. The prime consideration for requistioning this geophysical survey is to locate the hard locate the hard rock depth at the three piers remain to be constructed in the central portion of the bridge where rock could not be found even at double the conventional founding level on the flanking pillars. Three seismic lines around 110 m to 160 m have been laid using, 24-Channel signal enhancement seismograph of ABEM, with 5 m spacing, one along the bridge alignment and two lines parallel to this alignment on the upstream and downstream side of the axis of the alignment. Present seismic refraction data has yielded interesting results that depth to the hard rock for foundation purpose is of 20 m, 26 m and 18 m at three pier locations of the bridge respectively. Further it is noticed the depression type of feature emerged as a regional feature of a low velocity channel in the centre of the river. Stong current of water flow in this channel in the past had filled it by the flowing pebbles/boulders.

8 illus, 2 ref

023069   Rao S S;Murthy Y V N K;Ammineedu E (Scientis Regional Remote Sensing Centre, ISRO, PB 439, Nagpur-440010) : Value additoin to the cartographic potential of satellite data using global positioning system. J Indian Geophys Union 2004, 8(2), 135-41.

The RemoteSensing data acquired from space based platform has demostrated its potential in natural resources mapping, management, monitoring and development planning. Since the last few decades the images acquired from aerial platforms has large impact in mapping the topographical maps. Similarly, the satellite data, available with high spatial resolution, possess the high geometric fidelity and form as the basic source for gnerating base maps and topographic maps. The plannimetric accuracy of the aerial photos and satellite images is of prime concern for their usage in cartographic and thematic mapping. The Global Positioning System (GPS) based ground control points (GCP) are used for improving the plannimetric accurancy of the satellite images and generating value added products to facilitate cartographic mapping.

1 table, 21 ref

023068   Rao G V S P;Venkateswarlu M;Rao B S;Prakash Ravi (Palaeomagnetism Lab, National Geophysical Research Institute, Uppal Road, Hyderabad-500007) : Mantle plumes, continental flood basalt volcanism and palaeomagnetism. J Indian Geophys Union 2003, 7(3), 135-44.

Mantle plumes played a major role in plate tectonic processes leading to the super continents (Rodinia, Pangaea, Gondwanaland etc.) during the geological past. Especially more so in case of the Pangaea break-up duirng the Phanerozoic. Several cubic kilometers of basalatic magma has been poured out in short period in very quite succession over large areas covering million square kilometers. The hotsport tracks of moving continents over the mantle plumes reveal the directoin of movement of the continents with progression in age. These continental flood basalts record in them signature of the geomagnetic field at time of their formation giving a clue to their geographic location and nature of the geomagnetic field. An examination of these magnetic signatures in some of the continental flood basaltic volcanics reveals that the Cenozoic period continental flood basalts recorded frequent reversal of the geomagnetic field while the pre-Cenozic continental flood basalts recorded fewer geomagnetic field reversals. A detailed summary of the area of extent of continental flood basalt, radiometic dates and geomagnetic field reversals etc. of the known continental flood basaltic provinces of the Phanerozoic era are presented.

7 illus, 1 table, 70 ref

023067   Rao G V S P;Singh S B;Rao J M (Palaeomagnetisim Lab., National Geophysical Research Institute, Uppal Road, Hyderabad-500m 007) : Magnetic character of alkali rocks from Northwest India. J Indian Geophys Union 2003, 7(3), 145-54.

Magnetic property investigation of some alkali rocks from western and northerwestern India has been undertaken with a view to understand their magnetic behaviour. The rock types investigated include ultramafics, carbonatites, gabbros, lamprophyres, syenites, basalts, dolerites and alkali dykes collected from 14 sites in the states of Rajasthan and Gujarat. Natural Remanent Magnetic intensity (Jn), Susceptibility (K), Koenigsberger Ratio (Qn), laboratory demagnetizations using AF and thermal methods, Saturation Remanet Hysteresis, Susceptibility variation with Temperature, Lowrie-Fuller Test and petrographic observation are some of the studies carried on these rocks. Most the the magnetic properties observed on these rocks show a wide variation, over 2-3 order in magnitude, justifying their varying lithologies and magnetic mineral content. These alkali rocks reveal a spectrum of grain size with varying remanent and coercive forces noticed on them. The important magnetic mineral is (titano) magnetite occuring in CD and CD+MD domain states. These alkali rocks demostrate extreme stability of the magnetic signature with very high median destructive filed (mdf) values in excess of 10 to <62> 100 m T without superposition of any high blocking temperature secondary over prints.

6 illus, 2 tables, 25 ref

023066   Rajmohan N;Elango L;Ramachandran S;Natarajan M (Institute of Ocean Management, Anna Univ, Chennai-25) : Major ion correlation in groundwater of Kancheepurm region, South India. Indian J envir Hlth 2003, 45(1), 5-10.

Groundwater samples were collected from both dugwells and borewells in intensively irrigated area of Kancheepuram Taluk, Tamil Nadu, pH, EC and TDS of groundwater samples were measured in the site. The collected samples were analysed in the laboratory for Ca,Mg,Na,K,Cl,HCO₃,CO₃,SO₄,NO₃,P-PO₄ and Si-SiO₂. The results are used for inter elemental correlation analysis which indicates that most of the elements having good corrleation. Piper Trilinear diagram is used to find out the hydrochemical type of groundwater which shows that most of them are CaHCO₃ and the remaining are CaMgCl type. Hydrochemical characteristics of groundwater indicate that silicate weathering reaction is a probable source for high concentration of major ions

3 illus, 3 tables, 7 ref