ARCHIVAL

Department of Physics, St. Xavier’s College, Ahmedabad

Sector, 30A;Vashi, Navi-Mumbai, 400-705,

            The use of HVDC (High Voltage Direct Current) technology for transmission of bulk electrical power over long distances is more economical as compared to transmission in AC mode as the transmission losses in HVDC system are significantly lower. Besides, HVDC transmission has other advantages such as controllability, improved power system stability, and power modulation control. HVDC systems are designed to operate in bipolar mode, monopolar metallic return and monopolar ground return modes. A HVDC system requires specially designed earth electrode stations associated with the converter terminals of the HVDC transmission system. The earth electrodes provide an earth return circuit, facilitating the flow of current into the ground at the electrode stations. The design parameters of earth electrodes require consideration of the electrical conductivity structure of the subsurface in and around ground electrode sites. For a proper design, it is important to ensure that the site selected for the ground electrode has low near-surface resistivity. It is also necessary to ensure that the ground currents penetrate deep into the earth so that the grounding resistance/ potential rises in the vicinity of the electrode are within acceptable limits ensuring that the ground currents do not cause corrosion of buried pipelines and do not enter the neutrals of transformers installed in the close vicinity of the electrode station. Investigations using artificial source methods such as deep resistivity sounding pose logistic problems for these target depths. Magnetotelluric method is a very useful tool especially for the delineation of the electrical conductivity of the deep structure (up to 10 km depth) around the earth electrode site. We have carried out detailed investigations of some potential HVDC ground electrode sites employing magnetotelluric method to assess the suitability of these sites for the construction of Earth Electrode stations for India’s first ±800 kV, 6000MW HVDC multi-terminal transmission systems. MT method has been found to be a very useful tool for this purpose.

National Geophysical Research Institute, Hyderabad- 500 007, India

               Wavelet analysis has emerged as a potential tool for spectral analysis due to the time-frequency localization which makes it suitable for complex and nonstationary signals. In this paper, the strength of wavelet analysis is illustrated by three studies for (1) estimation of Hurst coefficient (2) ocean bathymetry data (3) gravity anomaly. The self affine behaviour is characterized by Hurst exponent and the application of wavelet transform is recommended for its estimation. Particularly, the bathymetry data can give important information related to the behavior of the crust and its correlation with other regions. The major thrust zones are delineated by transforming the gravity anomaly along Kiratpur-Leh-Panamik transect (~ 580 km) across NW Himalaya to wavelet domain.

²Department of Earth Sciences, Indian Institute of Technology, Mumbai

            Of the entire Himalayan terrain, the Outer Himalaya is believed to show excellent signatures of active tectonics. The Main Boundary Thrust (MBT) that separates the Outer and Lesser Himalayas has a recorded history of tectonic activities in the recent past. The present study incorporates an additional example of a major landslide event, the Amiyan landslide, associated with the MBT that passes through the toe of this landslide. The Amiyan landslide is one of the biggest debris slides in the Central Himalayan region. Two prominent fault scarps running almost transverse to the MBT have developed during the last 15 years. The slide has been increasing in size at regular intervals from an earlier 0.02 sq km in 1968 to 0.05 sq km till 1992. Thereafter, the process of continuous reactivation of the MBT and the formation of fault scarps has resulted in about 12-fold increase of the slide. Such a  topographical adjustment in response to active tectonics in this segment of the Himalaya suggests that the Outer Himalaya is possibly a major locale of present-day stress release in the Himalayan region. The results of this work have significant bearing on the seismotectonic, environmental, ground stability and the related aspects in the Himalayan domain.

²Department of Geology, Banaras Hindu University, Varanasi, India

          Although seventy percent of the Moon surface area is covered by meteoritic impact structures only 176 confirmed impact structures known on Earth hitherto. In India, the recently discovered Dhala impact structure, M.P. and the Lonar crater, Maharastra are the only two confirmed impact structures. The simple, complex and multi-ring impact structures are confirmed on the basis of mesoscopic and microscopic shock metamorphic features besides the physical and/or chemical signature(s) of the impactor (meteorite). The role of bolide impacts in the formation of mineral deposits and playing a crucial role in some of the major mass extinction events is also well known. The impact cratering process is considered responsible for the planetary evolution, landscape modification, and the presence of water and life on Earth.

Earth Science India Volume-2(III), 2009

         Gravity and magnetic surveys were conducted in an area about 5000 km² covering offshore region of the Qamar basin in the eastern part of Yemen. An attempt is made to address the gravity and magnetic signatures in term of structural features. In addition, seismic section (NIM-QAM-92-201) compiled by Nimir services limited, 1992 were used to illustrate subsurface structures in sedimentary sequences. Combined gravity and magnetic modeling along section QAM-92-201 by Geomodel 2.5D inversion technique suggest the thickness of sediment to vary from 3.2 to 5.3 km in the Qamar basin (offshore), and the basement rocks are divided into blocks because of existence of several faults extending from basement rocks to sedimentary rocks owing to strong tectonic activities. So the study area may be divided into several major blocks along the Qamar Gulf. It can be concluded that the sedimentary processes were affected by basement tectonics as

revealed by the seismic section.

          Rock mass are generally considered to be the most heterogeneous, complex and unpredictable geomaterials. It is difficult to fully understand its behavior under various loading conditions. In the present paper, an attempt has been made to calculate the maximum stresses at the crack tips (6m) after fracture developed in a rock specimen. Rock specimen was subjected to loading on servo-controlled auto feedback stiff testing system under compressional mode in a Brazilian cage. The fractured rock surface was considered for the determination of stresses all along the crack tips. The specimens were prepared and tested as per International Society of Rock Mechanics specifications for tensile strength determination. The specimen was placed under the Brazilian cage and subjected to compressional loading till it develop failure. The fracture mode followed the Griffith failure criteria. Various researchers have tried to calculate the stress at various point along the fracture plane and established relation with other physicomechanical properties, which is time taking and tedious job. In the present paper, a technique has been suggested to calculate maximum stresses at crack tips in a simple manner. The results can be used to establish the damage characteristic of the rock mass for improving safety and stability of existing structures and further help to improve production and productivity in mining and civil engineering constructions.

           Development of urban infrastructure along the west coast of the Arabian Gulf has caused major disturbance to the coastal environment and mangrove ecosystem during the past 40 years. The mangrove forests along this coastline have particularly been adversely impacted in most areas. Temporal Landsat MSS images of 1972-1973 and Landsat ETM images of 1999-2001 were used to detect changes in mangrove forests at 10 sites along the Arabian Gulf coast. The temporal changes in the mangrove covered areas were calculated using geometrically registered and radiometrically corrected historical Landsat images. Region masks were employed to isolate the unwanted area from the images. Normalized Difference Vegetation Indices (NDVI) were computed from the satellite images. The analysis of satellite images revealed massive losses of mangrove forests at six sites due mainly to the infrastructure development of coastal areas. The depletion of mangrove forests has been uneven in the region. Out of ten sites six sites showed varying degrees of reduction but in four sites 4, 8, 9 and 10 area covered by mangrove forests actually increased despite urban development. This was because areas of mangrove stands were left undisturbed during the development process. Although there are laws to protect mangrove forests in the region but they are not implemented effectively. This study shows the urgent need to protect mangrove ecosystem and consequently coastal marine habitats of region’s flora and fauna and natural protection from erosion from waves and currents.

             Assessment of groundwater prospects has been carried out for the Morar river basin in Gwalior district, Madhya Pradesh. Groundwater prospect of the basin has been delineated from the satellite data by the integration of geology, geomorphology, lineament and slope and classified as Excellent to poor groundwater potential zones using GIS. The results obtained from remotely sensed data cross checked with the bore well yield data and found in good agreement. This depicts the positive prospective zones in the study area for exploration of groundwater in future. Water level fluctuation map prepared from the pre- and post-monsoon water level data do not show any significant change except at some locations in alluvial area Net groundwater availability also calculated is about 63.634 MCM. The calculated annual draft of Groundwater from dug wells and tube wells for all users is 70.051 MCM revealing a deficit in groundwater storage in the Basin.

                This study is an attempt to analyse and highlight the present state of forests in Kashmir, which are under tremendous anthropogenic pressure. Extensive deforestation has resulted in harmful impacts on the overall environment especially on the health of the soil. The detailed studies were carried out in Kahmil Watershed of the Kashmir valley using Geo-spatial tools. The data of the Year 1974-75 and 2000 were used and changes in forest categories viz-a-viz soil erosion status have been analysed. The analysis revealed that the Kahmil watershed situated in the Kashmir valley is undergoing large scale deforestation. There has been a total loss of about 848 hectares of forest cover in about three decades. The most startling fact is the change in terms of density classes, where the change percentage is quite high. This deforestation has resulted in accelerated soil erosion. The area which was under the Moderate erosion class has reduced and that soil has further degraded and shifted to Moderate to severe class of erosion. Necessary remedial measuresshould be taken to check this deforestation and consequent soil erosion.

                Monitoring of hydrological data is pre-requisite for systematic and scientific designing of sub-surface drainage system for control water logging and salinity. In the present study, field experiments were conducted to determine various soil hydrological and physico-chemical properties (soil texture, color, permeability, infiltration, soil moisture characteristics, dry density, total dissolved solids, SAR, etc.) under saline soils around Gohana tehsil. The majority of the area is represented by silt loam texture with varying soil color having dominance of yellowish brown in top layer. The in-situ permeability was measured using Guelph Permeameter in the field and its values were found to vary from 0.01 to 0.69 m/d for silt loam. The SAR of the soil generally varied from 0.5 to 54. The infiltration data of area was fitted with Kostiakov’s type cumulative infiltration function (Y=a*tb) and its coefficient of determination (r2) varied from 0.956 to 0.998. The present data would be useful in planning of on farm land and water management strategies ultimately for enhancing the productivity of the land.

Comparison of the accuracy of SST estimates by artificial neural networks (ANN) and other quantitative methods using radiolarian data from the Antarctic and
Pacific Oceans
Shyam M. Gupta and Björn A. Malmgren

            The quality of quantitative estimates of sea surface water temperatures (SSTs) is evaluated for different techniques, Imbrie-Kipp transfer functions (IKTF), the modern analog technique (MAT), weighted-averaging partial least squares (WAPLS) regression, the maximum likelihood (ML) method, and artificial neural networks (ANNs), based on radiolarian faunal abundance data from surface sediments from the Antarctic and Pacific Oceans. Recent studies have suggested that ANNs may represent one of the most optimum procedures for estimates of paleo-SSTs. We, therefore, employed ANNs together with these other methods to estimate SSTs during February-April (TFA) and August- October (TAO) at a mean water depth of 40 m, wherein radiolarian abundances generally coincide with chlorophyll-a maximum. We used CLIMAP’s modern Antarctic radiolarian core top data and Pisias et al.’s Pacific Ocean core top data for the analyses. A portion of the datasets (75%) was used for training of ten ANNs per season, and estimates of error rates (root-mean-square-errors of prediction, RMSEPs) were made from the remaining observations, constituting an independent holdback (HB) set. The same training and HB sets were used for estimates of RMSEPs for the other methods. For the ANNs the RMSEP in the Antarctic Ocean dataset is as low as ~1.3oC for both TFA and TAO. In comparison, RMSEPs for the other techniques for TFA are higher in ranging between 1.8 and 2.0°C, whereas those for TAO are similar (1.4-1.5°C). Correlation coefficients (r:s) between observed and predicted SSTs using the ANNs are 0.97 for both seasons. In the Pacific Ocean dataset, RMSEPs derived from the ANNs are considerably lower for both seasons, 1.5°C for TFA (1.8-2.2°C for the other methods), and 1.4°C for TAO (the other methods 1.7-1.9°C). ANN-derived correlation coefficients (r:s) between observed and predicted SSTs are 0.98 for both TFA and TAO in the Pacific Ocean. Comparison of residual (estimated-observed) SST maps suggests that MAT and ANN produced lesser geographic trends than those of the other methods.

Radon Time Series and Earthquake Signals—a Study by SSNTD at Matigara (Darjeeling), India
Dipak Ghosh, Argha Deb, Subrata Haldar, Swarup Ranjan Sahoo, Rosalima Sengupta

            A survey of radon concentration in the soil gas in order to get premonitory signal of arthquakes is being carried out by us since last 4 years in Kolkata, West Bengal, India—which is known to be situated at non-active fault zone and since last 2 years in an active fault zone—Jalpaiguri (26A32BN, 88 A46BE), West Bengal. In extension of our work we have started the experiment in another active fault zone: Matigara, Darjeeling (26º43' N, 88º23'E), West Bengal, India, to have more confirmatory signal. We present the description of signal of the terrestrial gas 222Radon observed for a period of more than one year at a depth of 70 cm in the soil using passive detector –Solid State Nuclear Track Detector (SSNTD). The time series of radon shows a distinctive anomalous fluctuation prior to seismic events that ccurred within 1000 km from the measuring site. The results are obtained at two fault zone sites are compared and the present analysis provides further evidence in favour of using radon signal as a precursor of earthquake.

Sun-Earth-cosmic connection to understand early warning of Earthquakes
Saumitra Mukherjee

              Muon detector has the potential to function as Nano Sensor to infer possible earthquake in earthquake prone areas. It has been observed that 30 to 36 hours before the occurrence of the earthquake the magnetic field (Kp) and electron flux (E-flux) of the Sun-Earth environment changes. Using Sun-Observatory-Heliospheric Observatory (SOHO) satellite data it is possible to monitor the fluctuation every 15 minutes interval. It has been observed that before the occurrence of earthquake, nanoparticle (muon) intensity reduces, while the atmospheric temperature rises along with the increase in Kp and E-flux values. After the earthquake the atmospheric temperature falls suddenly with the rise in cosmic rays and fall in Kp and E-flux values. It has been planned by IHY, NASA and UNBSS (United Nations Basic Space Sciences) to design and install basic hybrid SEVAN (Space Environment Viewing and Analysis Network) in 14 locations across the world. Cosmic Ray Division laboratory of Armenia will supply photomultiplier of similar standards to all these 14 locations including Jawaharlal Nehru University, New Delhi, India. These detectors will record and correlate the intensity of cosmic ray data to predict various environmental perturbations including earthquake. Based on this plan it was attempted to correlate Kp, Eflux and chages in environment in different locations across the world with variation of cosmic rays collected from existing muon detectors.

Microscopic examination of concrete with and without corrosion inhibitor
B.N. Singh, P.P. Abhilash, V. Kumar and M.A. Quraishi

             The present paper addresses the mineral constituents and microstructural behaviour of concrete with and without corrosion inhibitor (i.e. calcium stearate) observed under petrological microscope. Mineralogically and texturally, these concretes are largely similar but microstructurally they are quite distinct. The concrete samples without calcium stearate are characterized by the occurrence of microcracks, voids and carbonation leading to lower the strength and durability of concrete. However, these features are less abundant in the concrete with calcium stearate. The microcracks and voids are infilled with cementitious materials, if calcium stearate is used as admixture. Therefore, the use of calcium stearate in concrete can enhance the strength and durability properties of concrete.

Possibility of artificial recharge in overdeveloped miniwatersheds: A RS-GIS approach
Bhagyashri C. Maggirwar and Bhavana N. Umrikar

            The stress on groundwater has become a point of concern for planners and researchers. The groundwater pumping is exceeding the recharge due to increased dependency on roundwater to cater the needs of the growing population. Therefore, the assessment of groundwater potential and scope for artificial recharge in the overdeveloped watersheds is very crucial. GV-41 5/8 and 6/8 miniwatersheds are such overdeveloped areas where the groundwater occurring in unconfined / semi confined shallow aquifer needs to be augmented by undertaking suitable artificial recharge structures in order to ensure economically viable yields of wells vis-à-vis increase the groundwater availability on sustained basis. For the purpose of assessment of groundwater potential in GV-41 5/8 and 6/8 miniwatersheds, detailed hydrogeological surveys were carried out in Aurangabad District, Maharashtra and the database was also used to find out the feasibility of artificial recharge structures. The present study is an attempt to find out the possibility of artificial recharge considering the existing water harvesting structures using Remote Sensing and Geographical Information System  techniques (RS - GIS).

Assessment and impacts of surface water environment in and around Jabalpur city, Madhya Pradesh, India
Medha Jha and Sanjay Tignath

             The physical, chemical and biological characteristics of surface water in and around Jabalpur city, M.P. have been studied to evaluate the suitability of water for irrigation and domestic uses. Samples of water were collected from various localities such as Narmada and Pariyat water supply system, various ghats of Narmada river, various tals and tanks, main drains of the city such as Omti nala and Moti nala and were analyzed for pH, electrical conductivity, temperature, dissolved oxygen, five days Biological oxygen demand , fecal coliform , turbidity, total solids, nitrates and phosphates.Water quality indices “WQI” developed in 1970 by the U.S. National sanitation foundation were calculated for these water samples. The results conclude that the water quality of water supply systems, various ghats of Narmada River is of medium quality and can be used for domestic use after suitable treatment. The water quality of various tanks and drains falls in the range of bad quality waters by index rating and can be used for irrigational purposes .This study is helpful to environmental planning and pollution control measures applicable to the area.

Hydro-meteorological disasters and climate change: conceptual issues and data needs for integrating adaptation into environment - development framework
Anil K. Gupta, Sreeja S. Nair and Vinay K. Sehgal

             Integrating Risk Reduction to the Environment and Development Framework at local and regional levels has now emerged as the core strategy for minimizing hazards and managing disasters. This strategy calls for a ‘paradigm shif by treating disaster management and climate change as developmental issues interlinked to each other and requiring common management approaches’. Disaster management comprises of (1) disaster risk management and (2) emergency organization for protecting natural, built and socio-economic environments from impacts at temporal and spatial scales. Damage and losses due to extreme events depend upon the magnitude and intensity of hazardous event along with the vulnerability of population, habitat, resources, and developmental settings, as against the capacity to withstand the risk. Designing the approach for convergence of Climate Change Adaptation and Disaster Risk Reduction (DRR) and mainstreaming towards development, it required an analysis of various components of environment-development complex that are to
be put into adaptation agenda. Availability of suitable, accurate and proper data is crucial for any assessment, planning or decision task. The present paper presents an effort of cross-sectional probe into various conceptual issues relating to hydro-meteorological disasters, climate-change impacts and disaster risks, issues for adaptation nd convergence, disaster risk reduction framework in India and examples of data needs at different stages for their better management.

Radiolarian abundance - a monsoon proxy responding to the Earth’s
orbital forcing: Inferences on the mid-Brunhes climate shift

Shyam Murti Gupta
National Institute of Oceanography, Dona Paula, Goa 403 004, India

           Radiolarian fluxes from the sediment traps moored in the southern Bay of Bengal suggested that radiolarians were invariably higher at times of higher sea surface temperature (SST >28oC) and moderately lower salinity (~33.5 psu) during the summers of 1991-93. It implied that higher SSTs due to summer heat and lower salinity due to rains might have affected the radiolarian fluxes during the monsoon. Hence, the down core radiolarian-yield in the unit weight as the percentage abundance may shed light on monsoon-sensitive radiolarian production through the geological past. It is tested in a well-dated radiolarian ooze-bearing sediment core collected from the central Indian Ocean in the southwest of the trap site. Radiolarian tests/g dry bulk sediment (Rads/g) yield from the sediment samples at every 4750 years (4.75 ka) time interval (δt) produced a time series for the last 485000 years (485-ka) during the late Quaternary. Rads/g was higher during the upper last 200-ka record than the lower section of the core implying higher radiolarian production in the upper part than in the lower part of the core. Blackman-Tukey and maximum entropy spectral analyses of the Rads/g time series revealed multiple cycles at ~126-, 95-ka due to the Earth’s orbital eccentricity, ~54-, 41-, and 31-ka due to axial tilt, 23-, 19-, and 17-ka due to changes in the precession of equinoxes, besides the 15-, 13- and 11-ka sub- Milankovitch cycles. The spectral results are further verified by multi-taper method using 90% reshaped spectrum, adaptive narrowband and high-resolution harmonic signals with robust noise and the statistical significance test (F-test), and the >90-99% significant cyclic components are reconstructed to visualize the variation in their amplitude through time. The reconstructed harmonic components revealed a conspicuous change in the trend of the amplitudes of ~95-, 54-, 41-, 31-, 17-, 15-, 13- and 11-ka cycles suggesting an effect of the mid-Brunhes epoch climate shift at around ~300-350-ka before present. The results substantiates the existence of multiple cycles at the eccentricity (126-, and 95-ka), tilt (~54-, 41-, and 31-ka) and precession (23-, 19-, and 17-ka) and sub-orbital bands (~15-, and 13-ka) as proposed by Berger (1977) in the astronomical data, which strengthens growing belief of multiple orbital cycles reported from pollens (Mommersteeg et al, 1995) and the radiolarian assemblages (Gupta, 2003) suggesting the cyclic changes in the summer-monsoon productivity during the Late Quaternary in the Central Indian Ocean sediments.

Seasonal and inter-annual variability of Chlorophyll – a in the Arabian Sea from SeaWiFS data

Rajeev Mudgal1, Mihir K. Dash2and P. C. Pandey2

1Wipro Technologies, Gurgaon
2CORAL, Indian Institute of Technology, Kharagpur

Taxonomic placement of a holectypoid echinoid genus Srivastava and Singh, 2001  

D. K. Srivastava
Centre of advanced study in Geology, University of Lucknow,
Lucknow – 226 007, India

Fluvial Palaeohydrological Studies in Western India: A Synthesis

Alpa Sridhar

Department of Geology, The M.S.University of Baroda, Vadodara 390 002

Abstract: The river basins of India are important repository of the late Quaternary hydrological and climatic changes. The long term (millennial scale) and short term (centennial scale) hydrological changes in these river basins can be reconstructed through the records of planform alterations and sediment deposits that occur during the rare extreme flood events. The status of fluvial palaeohydrological studies in western India and the future prospects are discussed in this synthesis. Almost continuous palaeoflood records spanning two thousand years is available from the bedrock rivers on western India, whereas older events dating back to ~ 5 ka have also been documented from the alluvial reaches. Though bedrock gorges are considered to be ideal sites for the preservation of palaeoflood deposits and related discharge estimations, the alluvial reaches of the rivers in western India owing to their unique geomorphic setup are equally promising. Regime-based palaeodischarge estimations for the average flows in these alluvial reaches would be significant in providing a regional history of the hydrological changes that have occurred in the river basins of western India.

Small-Scale Deformational Structures as Significant Shear-Sense Indicators: An example from Almora Crystalline Zone, Kumaun Lesser Himalaya 

K. K. Agarwal and R. Bali

Centre of Advanced Study in of Geology, University of Lucknow, Lucknow-226 007

Abstract: Small-scale deformational structures e.g. folds, asymmetric boudins, thin veins in an en-echelon pattern, small-scale duplex, shear zones and shear bands are the most common structural elements used as reliable shear-sense indicators in crystalline rocks. Most of these structures are observed in the Almora Crystalline Zone (ACZ) in Kumaun Lesser Himalaya, which is disposed in the form of a huge asymmetric synform. The shear-sense observed on the northern and southern flanks is found to be – top to north and top to south respectively.

Climate Change and its Future Impact on the Indo-Gangetic Plain (IGP)

H. S. Saini
Geological Survey of India, Faridabad

Abstract: The Indo-Gangetic plain (IGP) is an environmentally sensitive, socially significant and economically strategic domain of India where landscape, hydrology and fertility are threatened by climate warming and anthropogenic pressure. Irregular availability of water is going to be the biggest hazard in future. In case of increased water supply, the piedmont zone and river lowlands are threatened by erosion and sedimentation while in case of decreased water supply, the upland surface is endangered by salinization, desertification and drying-up of aquifers. Decline in food production will be the major problem. In order to make assessments of the environmental changes, concerted efforts should be initiated to understand the geological past and model the future. A pre-requisite is to develop a high resolution history of climate variations and their impact on landscape and ecology from the geological and historical records of IGP during the past 25 ka. Such data can help in the evaluation of forecasting scenarios, and thereby assist in developing mitigation plans regarding the environment. Artificially induced recycling the water can be one of the possible ways to maintain a minimum availability of water.

Speleothems from the Himalaya and the Monsoon: A Preliminary Study 

V. C. Tewari

Wadia Institute of Himalayan Geology

 33, General Mahadeo Singh Road Dehradun – 248001, Uttarakhand

Abstract: Speleothems (stalagmites, stalactites) have great potential for the records of past climate, environment and monsoon on a global scale particularly in the Asian region. Speleothems are found in all parts of the world and grow continuously through many glacial – interglacial cycles and their stable isotopic ratios and annual growth bands are useful for decadal to seasonal variations in rainfall. Some important speleothems from the Himalayan region such as Sahastradhara, Dehradun; Brahmakhal, Uttarkashi; Bhagirathi valley, Garhwal and Mawasmai caves from the Meghalaya have been studied. In the present paper, the oxygen and carbon isotope ratios from the Sahastradhara, Brahmakhal, Nagni  and Pratapnagar speleothems and cave drip water  has been recorded for the first time. The significance of speleothems and their relationship with the monsoon is discussed.

Sediment Characteristics and Heavy Mineral Distribution in Tamiraparani Estuary and Off Tuticorin, Tamil Nadu- SEM Studies 

M. Suresh Gandhi, A. Solai, K. Chandrasekaran and V. Rammohan

Department of Geology, University of Madras

  Guindy Campus, Chennai – 600 025

Abstract: The study area Tamiraparani  located between latitudes 8° 25΄ and 9° 13΄ N, and longitudes 77° 10΄ to 78° 10΄ E along the south- east coast of India. All samples were collected between Pre-monsoon July, 2003 and Post-monsoon February, 2004. The heavy mineral assemblage of the study region is governed by the distribution of different type of minerals. However, the assemblage is restricted to the dominance of few selective minerals like garnet (colourless), garnet (pink), zircon, rutile, chlorite, etc. From the SEM studies, it is observed that the grains are sub-angular with various surface solution features, rounded crescent like pits, straight net like sutures; v-shaped pits are noticed in pre and post-monsoon samples.  The coarser nature of the grains may be due to the influence of river activities. The weathered surface futures also noticed in few samples. The sediment texture, mineral and SEM studies, clearly indicate that in pre-monsoon the erosional activities are predominant than the post-monsoon. In both the periods, sediments transport was from river and estuary towards the beach and marine. In pre-monsoon, the deposited sediment were transported and shifted due to longshore current action.  But, in the post-monsoon period the sediments deposited due to the multi-source like riverine and marine influence is observed.

New Trends in Gondwana Palaeobotany

A.K. Srivastava

Birbal Sahni Institute of Palaeobotany, 53, University Road, Lucknow (U.P.)-226007

Abstract: Discoveries of insect wings, insect activities in fossil flora and microbial association with plant fossils have helped to understand the interrelationship of plants and insects and role of mico-organisms in Gondwana flora.

Brissid echinoid Eupatagus L. Agassiz, 1847 from the Khuiala Formation, Jaisalmer district, Rajasthan, India

D. K. Srivastava¹ and Hukam Singh²

¹Centre of Advanced Study in Geology, University of Lucknow, Lucknow – 226 007

² Birbal Sahni Institute of Palaeobotany, Lucknow – 226 007, India

Abstract: The spatangoid genus Eupatagus L. Agassiz, 1847 is recorded, for the first time, from the sediments of the Khuiala Formation (Early Eocene) exposed near Habur, Jaisalmer district, Rajasthan, India. The specimens are placed in a new species characterised by its large, oval test with mild frontal sinus; convex aboral surface; flat oral surface; anteriorly eccentric ethmolytic apical system; anteriorly eccentric kidney- shaped peristome; long, petaloid ambulacral petals; longitudinally oval periproct at the posterior truncation and imperforate, non crenulated tubercles.

Recently Studied Sedimentary Records from the Eastern Arabian Sea: Implications to Holocene Monsoonal Variability

Rajesh Agnihotri and Siby Kurian

National Institute of Oceanography, Dona Paula, Goa - 403 004

Abstract: Deep insight into exact mechanism(s) controlling past monsoonal variability on inter-annual to millennial time scales is a pre-requisite for developing predictive capability of monsoon on timescales relevant to human life. Reliable monsoon predictions developed by climate modelers play a crucial role for making country’s future economic programme. Basic data input to generally applied monsoon models is instrumental rainfall data, beyond which search for monsoon variability relies upon proxy records stored in various natural repositories such as tree rings, corals, cave deposits, lake and marine sediments. While tree rings, cave deposits and corals are capable of yielding paleo-monsoonal information on extremely high temporal resolution, continental margin sediments depositing in the Arabian Sea have provided relatively coarser but longer proxy records of monsoonal variability. Here we review some of such recently studied sedimentary records from precipitation dominated eastern Arabian Sea in an attempt to comprehend past monsoonal variability in Indian as well as global context. We also focus upon different proxies used so far in the Arabian Sea, their fidelity, limitations and future scope of using novel proxies for a better understanding of past monsoonal variability especially in the anthropocene epoch. 

Marine ¹⁴C Reservoir Age and Suess Effect in the Indian Ocean

Koushik Dutta
AMS Radiocarbon Laboratory, Institute of Physics
Sachivalaya Marg, P.O. Sainik School, Bhubaneswar – 751 005, India

Abstract: Apparent radiocarbon (¹⁴C) ages of marine biogenic samples that derive their carbon from surface seawater dissolved inorganic carbon are on the average about 400 years older than contemporary terrestrial woods or global atmospheric CO₂. This age offset is due to mixing of old carbon from the deep ocean and is referred to marine ¹⁴C reservoir effect. Both regional and temporal variations of ocean circulation pattern causes significant spatial and temporal variations in marine ¹⁴C reservoir ages and hence of biogenic surface marine samples. Knowledge of reservoir age is very important to accurately calibrate ¹⁴C-ages of biogenic carbonates and sediment organic matter from marine sediments that are frequently used in paleoceanographic studies. Here the concept of marine ¹⁴C reservoir ages and their quantification are discussed and data for the Indian Ocean region are reviewed. Regional variations of marine ¹⁴C reservoir ages and fossil fuel Suess effect for the Indian Ocean and the South China Sea are analyzed.

Variation in Erythemal UV Dose for Indian Cities as Observed from Global Ozone Monitoring Experiment Data 

Nandita D. Ganguly

 Department of Physics, St. Xavier’s College, Ahmedabad-380009

Abstract: Variation in Erythemal UV Dose (EUVD) for five Indian cities and their expected critical limits has been studied using the data obtained from Global Ozone Monitoring Experiment (GOME). The EUVD values are found to be higher and peak earlier at places located at lower latitudes than at higher latitudes. They are higher during summer / monsoon compared to winter. Seasonal variation in EUVD is more pronounced at higher latitudes compared to lower latitudes. EUVD variations show a negative correlation with solar activity and are observed to be well within the statistically calculated critical limits for these five Indian cities.

Chemical Characteristics of Water Soluble Components of Fine Particulate Matter, PM_2.5, at Delhi, India  

Suresh Tiwari¹, Manoj K. Srivastava², and Deewan S. Bisht¹

¹Indian Institute of Tropical Meteorology-Pune, New Delhi Branch,

Prof. Ram Nath Vij Marg, New Delhi-110060

Abstract : Aerosol samples in the size range up to 2.5µm were collected from January to December, 2005 at New Delhi, India, as a pilot experiment and analysed for organic (Oxalate and Formate) and inorganic (Sulfate, Ammonium, Nitrate, Potassium, Chloride, Sodium, Calcium and Magnesium) chemical components. Initial results show that the annual mean PM_2.5 concentration was 98.7µg/m³, which varied between 38 to 285µg/m³. The water soluble inorganic fraction constituted only 9% of PM_2.5 with SO₄^2-, NH₄⁺ and NO₃^- being the dominant ions followed by potassium. Annual cycle shows higher concentration of PM_2.5 during winter season (October to January) and the lowest during monsoon. It is attributed to the enhanced production of aerosols and prevailing meteorological conditions. The PM_2.5/PM₁₀ ratio (0.86) coupled with the Hy SPLIT air-mass back trajectories indicated that PM_2.5 was dominated by fine particles, when the winds passed through the eastern azimuth, where many industries and major thermal power plants are located.

Cosmic Rays and Earth’s Atmospheric Processes: A review

Devendraa Siingh  

Indian Institute of Tropical Meteorology, Pune-411 008, India

Abstract: The modulation of cosmic ray flux incident on the Earth’s upper atmosphere by solar activity results in changing the global electrical properties of the atmosphere, which is in turn believed to affect weather and climate. In this review paper an attempt has been made to summarize the present understanding of Earth’s atmospheric processes that are affected by Cosmic rays.

Use of Interactions between NAO and MJO for the Prediction of Dry and Wet Spell in Monsoon Season 

S.S.Dugam

Indian Institute of Tropical Meteorology, Pune-411008

Abstract:  The Indian summer monsoon exhibits prominent 30-40 day fluctuations with “active” periods of heavy rain interrupted by dry periods i.e. “Breaks”. The circulation anomalies associated with active/break monsoon cover the entire Indian Ocean remote tropics and North Pacific Ocean. A prolonged dry/wet period will result in severe drought/flooding, which have profound influences on the south Asia water cycle, agriculture and societal activity of more than one billion people. The atmospheric general circulation models have great difficulty in simulating the Intra-seasonal oscillation (ISO). Therefore, it is necessary to study the empirical relationship between various atmospheric processes, which are responsible for the ISO. In this paper, the analysis of North Atlantic Oscillation Index (NAOI) and Madden Julian Oscillation Index (MJOI) on daily scale is carried out in relation to daily Indian summer monsoon rainfall (June-September). The analysis is carried out for the period 1979-2001. Since the potential predictability limit for monsoon break is about 20 days, the 20 days running lag/lead correlation analysis between the NAOI and MJOI is found out for each year. It is observed that 20-day lag relationship between NAO and MJO is inverse and significant (0.1 level) and this relationship remains negative throughout the break monsoon period and in active phase it reverses. This twenty days lag relationship between NAO and MJO is potential predictor for break/ active monsoon conditions over the Indian region. The analysis is verified for major drought year 2002.

Geothermal Energy Resources and its Potential in India

P.N.Razdan, R.K. Agarwal and Rajan Singh

Geological Survey of India, Northern Region, Lucknow-226024

Abstract: Geothermal Energy is the vast reservoir of heat energy in the earth’s interior, whose surface manifestations are the volcanoes, fumaroles, geysers, steaming grounds and hot springs. About 300 thermal springs are known to occur in India, falling in orogenic (Himalayan) as well as non-orogenic (Peninsular) province. Thirty one areas have been examined in detail and finally, shallow drilling has been done in sixteen areas. The temperatures of these springs range from 35°C to the boiling point of water. On the basis of enthalpy characteristics the geothermal systems in India, are classified into medium (100°C-200°C)-and low enthalpy (<100°C) geothermal energy resources/systems. Medium enthalpy geothermal energy systems are associated with younger intrusive granites (as in Himalayas), major tectonic features/lineaments and rifts and grabens. The Low enthalpy geothermal energy systems are associated with Tertiary tectonism and neo-tectonic activity. The primary and most important aspect of geothermal system is to understand the heat source and its capacity for exploitation. Studies carried out, so far, have clearly pointed that adequate geothermal potential in respect of direct heat utilization and power generation does exist at several geothermal sites.  Reservoir simulation studies have suggested the possibility of generating over 3 MW electric power in Puga (J&K) field, if deeper levels are probed at least up to the depth of 500 m. The paper provides an overview on various geothermal fields of India and the status of exploration for future studies.

SFARF: Software for Classification of Fourier Shape of the Fold around Tamadhaun, District Almora, Uttarakhand

H. Thomas¹, S. Sujata¹ and A. Chandel² 

¹ Department of Applied Geology, ² Department of Computer Science and Applications University of Sagar, Sagar, M.P. - 470003

Abstract: Fourier (harmonic) analysis is a very simplified graphical method of plotting fold shapes in two dimensions. The authors have developed software (SFARF) to directly assign the class of fold shapes on the basis of the value of the ratio b3 / b1 (Fourier Coefficient). The various fold forms obtained by the software around Tamadhaun area reveal that fold developed in quartzite occurring in the study area vary in the range between sine-waves and parabolas to almost sine-wave, whereas the folds which are developed in phyllite and schist rocks are statistically between sine-waves to almost chevron.