April, 2014

April, 2014   ||  Volume 18 No.2



Imprints of tectonics and magmatism in the south eastern part of the Indian shield: satellite image interpretation

J. Nagaraju1,2 and T.R.K. Chetty1

1CSIR- National Geophysical Research Institute, Hyderabad-7
2Oil and Natural Gas Corporation Ltd, Rajahmundry
Email: trkchetty@gmail.com


The interface between the Dharwar craton and the southern part of the Eastern Ghats Belt, described here as the Terrane Boundary Shear Zone, is geologically a complex terrane. The zone also hosts many mafic-ultramafic and alkaline plutonic complexes and a recently reported Kanigiri ophiolite mélange. The zone has also been subjected to complex geological processes such as rifting, subduction, accretion and collision between 2.0 Ga and 0.5 Ga. Multi-scale image interpretations has been carried out to identify major structural/ tectonic elements as well as internal magmatic fabric trends of plutonic bodies, followed by detailed geological traverses and structural mapping. The results demonstrate that digitally processed satellite images are much more efficient than the normal satellite images in terms of structural and tectonic interpretations. The study also reveals new mapping results including several dominantly NE-SW, NW-SE and WNW-ESE/ ENE-WSW trending mega- and major- lineaments, consistent with field observations. An attempt is made to correlate genetic and spatial relationship of lineaments with regional tectonics and magmatism.


A review on shale gas prospect in Indian sedimentary basins

Kalachand Sain, Manish Rai and Mrinal K. Sen

CSIR-National Geophysical Research Institute, Uppal Road, Hyderabad - 500007
Email: kalachandsain@yahoo.com

Shale gas is a natural gas trapped within shales, which are fine-grained sedimentary rocks. Hydrocarbons are generated from organic-rich shale under an optimal temperature-pressure condition due to basin subsidence. A part of the generated hydrocarbons migrates and gets trapped in conventional reservoirs that can be produced commercially by standard techniques. Shale can act as both source and reservoir rocks. Depending on the type of organic matter and maturation level, unconventional hydrocarbons could be shale oil or shale gas or a combination of both. There is a sizeable deposit of shale formations in several sedimentary basins of India with different total organic (TOC) content and maturity history. The Cambay, Krishna-Godavari, Cauvery and Damodar valley are the four major basins of shale gas reservoirs as indicated by considerable thickness of shales; sufficient TOC (2 to 6 wt%) content; and good thermal maturity with vitrinite reflectance of more than 1.0. The Vindhyan, Upper Assam, Pranhita-Godavari and Rajasthan basins are other prospective basins that need to be probed by geo-scientific methods. The gas in these shale reservoirs can occur within the natural fractures or pore spaces or as adsorbed gas on the organic matter. This is considered as the next generation major energy resource after gas hydrates and coal bed methane.


Ionospheric precursors of M9.0 Tohoku earthquake on March 11, 2011
Suryanshu Choudhary, Parvaiz A. Khan and A.K. Gwal
Space Science Laboratory, Department of Physics
Barkatullah University, Bhopal-462026, India
Email: csuryansh@gmail.com

An earthquake of magnitude M 9.0 hit the Japan on 11th March 2011. The earthquake triggered one of the deadliest tsunamis. We analyzed the temporal variation of ionospheric parameters ten days before and five days after the main shock. These parameters measured by the ground based Ionosonde characterize the state of ionosphere. We have used the data of Kokubunji Ionosonde station, which lies at a distance of 440 km from the epicenter of the earthquake. The data analysis revealed a sharp enhancement in the height parameters hmF2, h/F2 and h/F of F layer seven days prior to the main shock, while critical frequency of F2 layer foF2 showed a slight decrease. We also examined the variation of electron density (NmF2), Ionospheric Electron Content (IEC) and ionospheric slab thickness parameters and found that while slab thickness increased around the same time the values of NmF2 and IEC underwent a decrease. Since the ionosphere was raised to higher heights the density decreased correspondingly. We also performed the cross correlation analysis of the Kokubunji station with other stations of Japan. From this analysis we found that on 3rd March 2011 Kokubunji followed a negative correlation with other stations of Japan.

Use and Abuse of Excess CO2 – An Overview
V.P. Dimri
CSIR Distinguished Scientist, NGRI, Hyderabad - 500 007
E-mail: dimrivp@yahoo.com

It is now confirmed that Global Warming is taking place and it’s influence on the Earth’s environment is found to be significant. Carbon Dioxide ( CO2) and other Green House gases are noticed to be significantly contributing to enhanced surface temperature of the earth, affecting the Climate, degrading the quality of our environment and enhancing climate related vulnerabilities and hazards. A comprehensive exposition of the role of CO2 is presented. Usage of CO2 in enhancing oil from oil field is also discussed.

Understanding area specific recharge process from Vadoze zone resistivity variations – a case study in basalt watershed, Ujjain district, Madhya Pradesh
*R. Rangarajan1, Rolland Andrade2, G.B.K. Shankar1, D. Muralidharan1 and E. Peters3
1CSIR-National Geophysical Research Institute, Hyderabad
2Central Water and Power Research Station, Pune, GOI
3CSIR-Advanced Materials and Processes Research Institute, Bhopal
Email: rangarajanngri@gmail.com

Spatial variability in parameters used in groundwater resource estimation and budgeting over an area always compromised with averaging and distribution. Among the parameters, the natural recharge spatial variability found to influence critically in resource assessment. To understand the spatial variability in principal recharge component, an attempt is made to relate the vadoze zone characteristics by integrating results of natural recharge, injected tritium tracer studies, infiltration and electrical resistivity tomography over black soil covered basaltic Ghatiya watershed in Ujjain district, Madhya Pradesh. Analysis of recharge function at three sites representing upper (recharge area), middle and lower (discharge parts) is found to be a function of vadoze zone resistivity characteristics and an exponential function of infiltration rate. The relationship may help in getting the dependency in spatial distribution of recharge with limited spot recharge measurements and resistivity characteristics of vadoze zone of intervening areas and infiltration indices.

Cold fronts/ upper air troughs and low level subtropical anticyclones in South Indian Ocean and Indian summer monsoon rainfall
Vinod Kumar, A.K. Jaswal1, S.D. Agre2, M. Satya Kumar3, N.I. Pareekh2 and P.S. Fernandes2
Shyam Bhawan, Ashok Nagar, Road # 11, Kankarbagh Colony, Patna-800020
1Additional Director General of Meteorology, Pune-411005
2Meteorological Office, Chatrapati Shivaji International Airport, Mumbai-400099
3House # 6-3-565, Flat # 301, Akshaya Apartment, Somajiguda, Hyderabad-500082
E mail: vinodmanjusingh@yahoo.co.in

The movement of cold fronts with associated westerly waves from west coast of South Africa (10°E: even from 40°W) to west coast of Australia (120°E) during south west monsoon season influences Indian summer monsoon rainfall significantly.Moderate/ deep cold fronts have been observed in southern hemisphere east of 30°E and north of 30° south/ 25° south, during normal/ excess Indian summermonsoon months. Feeble cold fronts, which are observed during deficient monsoonmonths, do not penetrate north of 30°south. Westerly waveshave been observed from 850 hPa to 200 hPa or even up to 150 hPa pressure heights. It is well known thatcold fronts are closely associated with low pressure systems, normally lying at the leading edge of high pressure systems. They tend to move towards the equator and eastward. It is also well known that low and medium clouds such as Cumulus (CU), Cumulonimbus (CB), Altocumulus (AC) and Altostratus (AS) are observed at the cold front. In the rear of a cold front AC and AS clouds are observed. Because of presence of high pressure area, in the rear of a cold front, strong pressure gradient is observed from South Indian Ocean to north of the equator. Moisture generatedby the low level westerly waves/ troughs, in South Indian Ocean, can be observed by presence of thick AS clouds in the rear of cold fronts. Moisture generated (cold air mass), below 8000 feet (base of AS clouds) is transported to Indian Seas by low level subtropicalanti cyclones (from 850 hPa onwards) located between 40°W to 120°E, through southeasterly trades.This has been confirmed by 850hPa relative humidity (RH) and winds anomalies, for 21 normal/ excess and 20 deficient monsoon months for 31years period. So, the region from 40°W-120°E and north of 30°S in southern hemisphere is most vital for Indian Summer Monsoon Rainfall.

Electrical Resistivity(ER), Self Potential (SP), Induced Polarisation (IP), Spectral Induced Polarisation (SIP) and Electrical Resistivity Tomography (ERT) prospection in NGRI for the past 50 years-A Brief Review
CSIR-National Geophysical Research Institute, Hyderabad - 500007

Geo-electrical techniques are used extensively to locate hidden targets that are conductive and resistive in nature. Efficacy of various branches of these techniques has been enhanced due to concerted theoretical, laboratory and field studies. Scientists of CSIR-NGRI played a significant role in strengthening technical base of these techniques. An attempt is made through the present review to project importance of various research initiatives, spanning over five decades.

Kinematics of “top –to-down” simple shear in a Newtonian Rheology
Soumyajit Mukherjee
Department of Earth Sciences, Indian Institute of Technology Bombay, Powai,
Mumbai- 400 076, Maharashtra, INDIA
E-mail: soumyajitm@gmail.com

Freshwater ecosystems and biodiversity—A Case Study of Kolleru Lake, India: A Review
Scientist –G ( Retd), CSIR-NGRI, Hyderabad-500 007
E-mail: parvatarreddy@gmail.com

Freshwater Lakes, especially those that have significant importance from socio-economic point of view and sustenance of bio-diversity need to be protected from various manmade degradations. To bring in to focus the importance of organised restoration of degraded freshwater Lakes an effort is made through this write up to expose various facets of the problems encountered in Kolleru Lake and implementation of organised restoration strategies to overcome various setbacks and the future course of action, by synthesising available information

News and views at a glance