Current Issue

September, 2017   ||  Volume 21 No.5


Geophysical surveys over Bakreswar geothermal region in Birbhum district, West Bengal

D.C. Naskar
Eastern Region, Geological Survey of India, Bhu-Bijnan Bhavan, DK-6, Sec-II, Salt Lake City, Kolkata-700091

Magnetotelluric (MT) and resistivity surveys were carried out in the geothermal region of Bakreswar, West Bengal to obtain a preliminary idea about the nature of conductivity structure and to prepare a meaningful conceptual model of the geothermal region. 
In resistivity traverse along Bakreswar-Asanshuli, one conductive anomaly zone is mapped at n (separation parameter) =10 in between 1200-1500 m stations. Bakreswar hot spring lies adjacent to it and geologically a hidden fault could be the source of the hot spring. In the resistivity traverse along Chandrapur-Tantipara, the presence of subsurface conductive bodies (50-400 Ohm m) is inferred between stations 1000-1200 m at a pseudo depth of 400-700 m. This source could be in the form of structural breaks like shear zones/geothermal region. 
1D inversion shows a high resistivity layer overlain by a conductive layer which is interpreted at a depth as shallow as 3001 m at Rajnagar but at a greater depth of 38103 m at Nakrakonda. This steep gradient in between these two stations could possibly be attributed to a fault zone. Similar type of fault is inferred in between Belsara (7484 m) and Nakrakonda (38103 m). 2D inversion shows that the entire lower crust consists of an anomalous structure of conductive layers with a relatively low-resistivity (approximately in the range 1–90 Ohm-m) imbedded in the high-resistivity background. A highly conductive feature is inferred beneath Lokpur and Idgachha region extending from shallow surface into the deep crust. This feature is interpreted as a potential reflection of the partially melted magma in the upper crust, which might correlate to mantle upwelling along the fault. It is likely that the magma is the heat source of the Bakreswar geothermal system. Thus this inference potentially provides new geophysical evidence to understand the occurrence of the partially melted magmas in the upper crust. These models suggest for a possible recovery of heat from heterogeneous, fractured geothermal reservoirs. The MT exploration of the geothermal reservoir can provide valuable constraints on the physical conditions within the delineated fault zone. It has guiding significance for the exploration of other geothermal resources along fault zones especially in granite areas.
Key words: Natural source MT, DC resistivity traverse, Geothermal Region, 1D inversion, 2D inversion..

Deep Resistivity signatures across the Chitradurga shear zone of Dharwar craton, India

B. Veeraiah1 and G. Ashok Babu*2
1Department of Geophysics, University College of Science, Osmania University, Hyderabad-500007, Telangana, India
2CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad -500 007, Telangana, India
*Corresponding Author:

The deep resistivity signatures of the crustal scale Chitradurga shear/fault zones, which divide the Dharwar craton of peninsular India into two major crustal blocks, are investigated. Deep Resistivity Sounding (DRS) data acquired at twenty-nine locations spread in a near SW-NE direction across the craton yielded significant insight into the resistivity distribution within the N-S trending Chitradurga shear zone and adjoining major geological features. A major resistivity transition observed in the interpreted geo-electrical section is depicting a clear separation between the eastern and western parts of the Dharwar craton. The eastern part of the Chitradurga schist belt is indicated by high resistivity compared to the western part. This can be attributed to younger intrusive (Closepet Granite). The study has further indicated the extension of the shear/fault zone at depth and is characterized by low resistivity. The presently obtained electrical depth section prepared up to about 1500m bears correspondence with the available gravity variation along the traverse. 
Key words: Deep Resistivity soundings, Dharwar craton, shear/fault zone.
Key words: Hydro-geochemical evolution, Water quality, Domestic and Irrigation use, Salinity hazard, Sodicity hazard, Bicarbonate hazard, Magnesium hazard.

Efficacy of Electrical Resistivity techniques for groundwater prospecting and aquifer mapping in a hard rock terrain of southern India

Ratnakar Dhakate* and S. Sankaran
CSIR-National Geophysical Research Institute
Uppal Road, Hyderabad-500007, India
*Corresponding Author: 

One dimensional (1D) and two dimensional (2D) electrical resistivity investigations were carried out in a hard crystalline terrain of Karnataka state, South India with an objective of pin-pointing the groundwater location and delineating the aquifer geometry. Based on the interpretation of 1D and 2D resistivity data, sixteen locations were recommended and drilled for exploiting groundwater. The yield of newly drilled bore wells ranged from 0.095 to 19 m3/hr. On comparing the lithologs and derived layer parameters, it is inferred that the success of the wells depends mostly on fractured granites/gneisses than the weathered layer. Based on the yields of the wells, the valley filled region in the central part (towards east) of the investigated area appears to be more water bearing. To maintain the sustainable yield of these newly drilled bore wells, a few rainwater harvesting pits were also recommended. The efficacy of the VES and ERT methods is well revealed by a good match of layer parameters and litholog data.
Key words: Vertical Electrical Sounding (VES); Electrical Resistivity Tomography (ERT); Aquifer mapping and Groundwater prospects.

Morphotectonic of Sabarmati-Cambay basin, Gujarat, Western India

Vasu Pancholi*1, Girish Ch Kothyari1, Siddharth Prizomwala1, Prabhin Sukumaran2, R. D. Shah3, N. Y. Bhatt3 Mukesh Chauhan1 and Raj Sunil Kandregula1
1Institute of Seismological Research, Raisan Gandhinagar, Gujarat
2Charotar University of Science and Technology (CHARUSAT), Vallabh Vidhyanagar, Gujarat
3Department of Geology, MG. Science College Ahmedabad, Gujarat
*Corresponding Author:  

The study area is a part of the peri-cratonic Sabarmati-Cambay rift basin of western Peninsular India, which has experienced in the historical past four earthquakes of about six magnitude located at Mt. Abu, Paliyad, Tarapur and Gogha. Earthquakes occurred not only along the two major rift boundary faults but also on the smaller longitudinal as well as transverse faults. Active tectonics is the major controlling factor of landform development, and it has been significantly affected by the fluvial system in the Sabarmati-Cambay basin. Using the valley morphology and longitudinal river profile of the Sabarmati River and adjoining trunk streams, the study area is divided into two broad tectono-morphic zones, namely Zone-1 and Zone-2. We computed stream length gradient index (SL) and steepness index (Ks) to validate these zones. The study suggests that the above mentioned structures exert significant influence on the evolution of fluvial landforms, thus suggesting tectonically active nature of the terrain. Based on integration of the morphometry and geomorphic expressions of tectonic instability, it is suggested that Zone-2 is tectonically more active as compared to Zone-1. The results obtained from morphotectonic studies are verified during the field work and validated with the present seismicity pattern. 
Key words: Morphometric analysis, Sabarmati-Cambay basin, Western India.

Deep Mantle Plumes and Origin of life on the Earth

Scientist (Retd), CSIR-NGRI, Hyderabad-500 007, Telangana State

Origin of the life on the earth remains one of the great mysteries in our scientific exploration of the Nature. The investigations for this naturally require combining the geo- and bio- sciences. The present study outlines the two leading hypotheses for the origin; viz. “The primordial soup” and “ocean floor based alkaline hydrothermal vents”, along with search for the antiquity of life on the earth. Further the study discusses volcanism triggered conditions/or the thermo-chemical environment that could lead to the emergence of life. It is proposed here that during the earliest phase of earth’s life (i.e. in the Hadean era) the deep mantle plumes (DMP) seem to be the basic (or root) driving source for creating the essential pre-requisites, P.T/ conditions & the chemical/ bio-chemical processes that eventually gave rise to the “Miracle of life”.
Key words: Deep mantle plume, Origin of life, The primordial soup, Hydro thermal vents, Hadean era..

Petrography and geochemistry of the Amphibolites from southeastern part of Yerapalli schist belt, Eastern Dharwar Craton, India

Tushar M Meshram*1, Devasheesh Shukla1, Kallola K. Behera1, Satya Narayana Mahapatro2, V. Adinarayana Reddy2, and K. Chandramouleeswara Rao2
1Geological Survey of India, Hyderabad, Telangana
2EPMA Laboratory, Geological Survey of India, Hyderabad, Telangana
*Corresponding Author:

The Yerapalli schist belt (YSB), predominantly constituted of amphibolites, is considered to be extension of the Nellore-Khammam Schist Belt (NKSB) of the Eastern Dharwar Craton (EDC). Based on field characteristics and fabric elements, two types of amphibolites have been identified in YSB. The NNW-SSE trending older banded and foliated amphibolite associated with metasedimentaries, and the ENE-WSW trending massive amphibolites. Petrographically, the foliated amphibolites consist of amphibole, quartz, plagioclase, chlorite and magnetite, whereas the massive variety is composed of amphibole, plagioclase and chlorite with accessory apatite and titanite. Geochemical studies indicate that the foliated amphibolite enclaves plot in sedimentary field (para-amphibolite), while the massive variety plot in igneous field (ortho-amphibolite). In Niggli c-mg diagram, the ortho-amphibolite indicates characters similar to those of Karroo dolerites, whereas a mixture of pelite-dolomite is observed for para-amphibolite. Similarly, para-amphibolite consist of Mg-rich amphibole and chlorite, while ortho-amphibolite has Fe-rich amphibole and chlorite. In chondrite-normalised REE plots, the ortho-amphibolite shows depleted LREE, with low amplitude positive Eu anomaly while the para-amphibolile exhibits flat REE pattern. This contribution brings out succinct details of field, petrographic mineral chemistry and geochemical charters occurrence of two distinct varieties of amphibolites in the YSB and establishes their igneous and sedimentary parentage.
Key words: Para-amphibolite, Ortho-amphibolite, Yerapalli Schist Belt (YSB).

Variability of lightning, convective rain and solar activity study over South/Southeast Asia during ENSO episode for the 
period of 1998-2010

Devendraa Siingh1, T. Dharmaraj*1, P. Ramesh Kumar2, Rajesh Singh3, Sanjay Kumar4, G.R. Chinthalu1, M.N. Patil1 and R.P. Singh4
1Indian Institute of Tropical Meteorology, Pune, India
2Department of Meteorology and Oceanography, Andhra University, Visakhapatnam-530003, India
3KSK Geomagnetic Research Laboratory, Indian Institute of Geomagnetism, Allahabad, India
4Department of Physics, Banaras Hindu University, Varanasi- 221105.
*Corresponding Author:

Analysis of monthly mean data of lightning and convective rain for the region 8° N - 35° N, 60° E - 120° E and for the period 1998-2010 show that lightning and convective rain are not significantly influenced by solar parameters such as sunspot number, total solar irradiance (TSI) and solar radio flux whereas CAPE anomaly and temperature anomaly have significant impact on the total lightning flash rate and convective rain during ENSO periods. Further no significant relation between cosmic ray flux and total lightning flash rate during La Niña period is obtained. On the other hand, for the El Niño period and for the total period, we get statistically some significant negative correlation between cosmic ray flux and total lightning flash rate. However, it is not possible to make any comment on the general relation between cosmic ray flux and total lightning flash rate due to contaminating global effects, regional effects and cloud microphysics. In the monthly variation of the parameters, temperature anomaly can be used as a proxy for the total lightning flash rate for the region under consideration. Most of the variation in ozone during the ENSO period is due to lightning. In the region considered here, role of aerosols in producing lightning and rainfall is quite comparable during La Niña period. On the other hand, aerosols contribute more towards production of lightning than producing rain during El Niño due to changes in cloud microphysics and cloud electrification. 
Key words: El Niño, La Niña, Lightning flash rate, ENSO, Convective rain rate, Cosmic rays, Solar activity, CAPE, Aerosol optical depth.

Distribution of Lightning Casualties over Maharashtra, India

Omvir Singh*1, Pankaj Bhardwaj2 and Jagdeep Singh2 
1Professor, Department of Geography, Kurukshetra University, Kurukshetra-136119, Haryana, India
2Research Scholar, Department of Geography, Kurukshetra University, Kurukshetra-136119, Haryana, India
*Corresponding Author:

This study investigates human casualties as a result of lightning strikes in Maharashtra state of India. Records dating from 1979 to 2011 have reported about 2363 casualties resulting from 455 lightning events. On an average 72 casualties per year have been reported with significant increasing trend. About 51 per cent events and 46 per cent casualties have occurred only in six districts of Nagpur, Chandrapur, Yavatmal, Nashik, Amravati and Akola. Remarkably, Vidarbha region has reported about 4 times more lightning events and about 3 times more casualties than second highest Marathwada region. The lightning events and casualties rate per million population per year in the state has been found to be 0.15 and 0.82, respectively. Male casualties are more prominent than females and children, which is probably due to the larger proportion of males performing their work outdoors. The peak lightning events and casualties have been witnessed during the monsoon season, whereas lowest during winters. It is believed that the results of this study will be helpful in developing better disaster management guidelines for lightning safety and preparedness. Apt audio-video presentations would help in better education of vulnerable segments of our society, farmers and daily wage earners present in the rural environment.
Key words: Lightning, Thunderstorm, Casualties, Gender variations, Maharashtra.

Climate change, Environmental impacts and Sustainable development

U.S. De1 and D.M. Rase*2
1Visiting Faculty, India Meteorological Department, Pune
2India Meteorological Department, Pune
*Corresponding Author:

It has been revealed by proxy data that terrestrial and extra terrestrial factors were mainly responsible for paleoclimatic changes. However, since the industrial revolution during the past one hundred fifty years, the climate change is driven by anthropogenic factors, in addition to natural. The impacts of the climate changes, during the last hundred years on our environment are found to be detrimental in many ways. The paper presents some of these aspects and the international efforts to face the challenges of anthropogenic involvement in climate change. A way forward could be sustainable development by arresting negative factors that are adding to degradation of our environment, including uncontrolled use of non renewable natural resources.
Key words: Global warming, Climate change, Paleoclimate, Mitigation, conference of parties (COP).

Aerosol concentration over Ranchi urban area and South Karanpura Coalfield region, Jharkhand, India-A comparative geospatial appraisal

Akshay Kumar* and Akhouri Pramod Krishna
Department of Remote Sensing, Birla Institute of Technology, Mesra, Ranchi- 835215, Jharkhand, India
*Corresponding Author:

Atmospheric aerosols are known to influence the air quality in urban, rural and mining regions of the world. The present study investigates the concentration of aerosol optical thickness (AOT) measured at 40 locations in Ranchi urban area (RUA) within urban boundary layer and 42 locations in South Karanpura Coalfield region (SKCR) to quantify the atmospheric conditions over the region. Aerosol concentration has been measured by using a five channel (340-1020 nm) handheld microprocessor-based MICROTOPS-II Sunphotometer during the peak winter season, in the month of January 2014. It is observed that AOT concentration is higher (1.92-3.33 at 340 nm) in the vicinity of thermal power plant, sponge iron factory, mining area, coal-based small industries and construction sites, whereas lower (<1.50) in the forest and low population density areas and within agricultural lands. In comparison with the urban area of Ranchi city, AOT concentration showed variation with high values (0.68-0.34 at 340 nm) at main centers of railway and road traffic junctions, whereas lower concentration (<0.34) in the residential area. The AOT values are higher for smaller wavelengths (340 nm) and lower for higher wavelengths (1020 nm) indicating the dominance of fine particles in the atmosphere compared to larger size particles. We have also derived Ǻngstrӧm parameters (α, b) for the wavelength pair 340-870 nm. Results show that the values of ‘α340’ have a range of 0.47 to 2.59 and 0.60 to 1.04 in mining region and RUA, respectively. The values of ‘ß’ have a range of 0.03 to 1.92 and 0.07 to 0.20, respectively. This study suggests that the aerosol concentration is higher over mining region as compared to urban areas due to the expansion of industries and coal mining activities over the years.
Key words: Aerosol optical thickness, MICROTOPS-II Sunphotometer, Ǻngstrӧm exponent, GIS, Coal mining, Urban area.

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Announcement - 54th Annual Convention of IGU

1Last updated: 09/08/2017