CONTENTS OF JANUARY-APRIL 2012, Vol.XXXIII   No.1-2

 

Geoelectrical Investigations for Shallow Ground Water in a Canal Command of Orissa.

Shishir Raut

 

Gas Geochemistry as a Tool for Risk Reduction in Hydrocarbon Exploration.

H.C. Pande, Ashok Raina, Pankaj Sharma A. K. Mittal, and R. R. Singh

 

Aero-Electromagnetic Signatures over a Zinc-Nickel Prospect in Umarvaniyan Block, Udaipur District, Rajasthan.

Dinesh Gupta, Suresh Chander, C.P. Sisodia and I. R. Kirmani

 

Evidences of a Post Cretaceous Transpressional Regime Interpreted from the Morphotectonic Features in the Continental Shelf Between the Rushikulya and Kushabhadra Rivers, Orissa Coast, India.

B. K. Nandi, R. Singh, S. R. Samadder, G. K. Dutta, B. P. Pal and L. K. Das

 

Airborne Magnetic Dat A Source of Subsurface Geological Information for Uranium Exploration:A Few Case Studies over some Proterozoic Sedimentary Basins of India.

M. Bandyopadhyay

 

BOOK REVIEW : Geology of India ( 2010 Edition).

M. Ramakrishnan and R. Vaidyanadhan

 

 

Geoelectrical Investigations for Shallow Ground Water in a Canal Command of Orissa

 

Shishir Raut
Directorate of Water Management, Bhubaneswar, Orissa -751023
E-mail: shi_wtcer@yahoo.com

 

 Abstract

   Sixteen Vertical Electrical Soundings (VES) of Schlumberger configuration and two profiles of Wenner configuration respectively were laid out in three different villages covering an area of approximately 410 ha in Balipatna canal command of Orissa. Five geoelectric layers were found in the area within a depth of 40 m below ground level. VES data from two points were compared with bore hole data to assign resistivity values to different strata. Using resistivity fence diagram the quantity of ground water under shallow aquifer was computed to be around 12.2 ha-m. Chemical analysis of ground water samples showed that the quality of ground water was good with low salinity and low alkali hazard and could be grouped as C1S1 under USDA irrigation water quality classification.

 

Key words: Vertical Electrical Soundings, ground water, geochemical analysis

 

 

 

Gas Geochemistry as a Tool for Risk Reduction in Hydrocarbon Exploration.

 

H.C. Pande, Ashok Raina, Pankaj Sharma A. K. Mittal and R. R. Singh
Geochemistry Division, DMIPE, ONGC, Dehradun-248195
E-mail: pandeharish@hotmail.com

 


Abstract

   Geochemical characterization of gas seeps and natural gas produced from the subsurface reveals the origin of the gas. Two distinct processes generate gaseous hydrocarbons in a reservoir, bacterial activities during diagenesis and thermal cracking of petroleum precursors, which produce biogenic and thermogenic gases respectively. Whereas bacterial gas is mainly enriched in methane, thermogenic gases contain an abundance of higher hydrocarbons in varying proportions. Chemical composition and stable isotopic characteristics also give an insight into the association of the gas with a liquid hydrocarbon pool and its maturity.

 

   Study of a gas seep undertaken in the past from a tube well in Rahatgarh in MP, India, revealed its predominantly biogenic origin and a gas collected from Bengal basin well was characterized as thermal high maturity thermal gas based on their chemical composition and stable carbon isotopic signatures.

 

   Whereas bacterial gases reported from seeps and tube wells may be of commercial importance, associated wet gases produced from the subsurface may lead to a commercial discovery when integrated with other geological and geophysical data.

 

 

 

Aero-Electromagnetic Signatures over a Zinc-Nickel Prospect in Umarvaniyan Block, Udaipur District, Rajasthan.

 

Dinesh Gupta*, Suresh Chander, C.P. Sisodia and I. R. Kirmani
*GSITI, Zawar Centre, 15-16 Jhalana Doongri, Jaipur-04
AMSE Wing, West Zone, GSI 15-16 Jhalana Doongri, Jaipur-04

 

Abstract

 

   Aero-geophysical surveys have been carried out in the study area by BRGM-CGG of France during 1971-72 using INPUT system comprising electromagnetic, magnetic and radiometric methods. Several anomalous zones for sulphide mineralization have been identified in Sanjela-Manpur-Lohagarh metallogenic belt of Udaipur District, Rajasthan. The study area, Umarvaniyan block forms the part of Manpura-Lohagarh zone of Sanjela-Manpur-Dugocha belt, Udaipur district, Rajasthan. Six channel aero electromagnetic intercepts have been recorded over the study area. Decay curve has been prepared to assess qualitatively the type of six channel intercepts from the mineralization point of view. Result are presented in this paper and correlated with the mineralization

 

   Decay curve plots of the six channel aero-em intercepts falling over the Umarvaniyan area are showing slow decay with strong curvature indicative of poor conductor with depth persistence. Poor conductivity is attributable to zinc mineralization.

 

   Systematic litho geochemical surveys in Umarvaniyan brought out an anomalous zone in phyllitic dolomite over a strike length of 400m. Anomalous zinc values between 820ppm and 2400ppm with corroborative nickel values between 100ppm and 410ppm have been recorded.

 

   Exploration by drilling in Umarvaniyan block has brought out low grade zinc(+ nickel) mineralization for a strike length of about 500 m, which is broadly in agreement with the aero em signatures.

 

Key words: Aero-geophysical surveys, Umarvaniya block, Electromagnetic, decay curves, Zinc-Nickel.


 

 

Evidences of a Post Cretaceous Transpressional Regime Interpreted from the Morphotectonic Features in the Continental Shelf Between the Rushikulya and Kushabhadra Rivers, Orissa Coast, India.

 

B. K. Nandi, R. Singh, S. R. Samadder, G. K. Dutta, B. P. Pal and L. K. Das
Geological Survey of India, Marine Wing, Kolkata

 

Abstract

 

   Shallow seismic reflection data along several coast perpendicular traverses off Chilka Lake in Orissa, have brought out the dispositions of the seabed and a few sub-seabed reflectors along with an important morphological upwarp extending over 115 km with a relief of 3-8m associated structural breaks. These breaks are mostly aligned in NE-SW direction.

 

   Free-air (FA) gravity anomaly of the offshore and onshore region between the Mahanadi and Godavari basins clearly brings out an N-E trending gravity high or crustal thinning along the Eastern Continental Margin of India (ECMI). This FA anomaly and the geometry of the shore line is in sharp contrast to the gravity anomaly as well as the shore geometry down south, where the ECMI suddenly turns N-S along the 80 E meridian. Superimposed on the gravity high referred above, a profound gravity low has been identified in the shelf area off Chilka Lake. This gravity low zone is found to be an approximately 5.4 km wide canyon/channel cut, in the shelf area, ahead of the shelf-break, with a vertical relief of 400 m from the seafloor. The actual relief must be much larger, a part of which is presently filled up by sediments. Obviously presence of such NE-SW trending morphotectonic unit in this part of the shelf area is a very significant feature in the shelf morphology which is absent down south.

 

   Presence of an upwarp in the sea floor of the dimension of 115kmX8m associated with a reverse fault on the seaward side with identical down throw of 8m, conclusively proves a compressional tectonic regime in the post Cretaceous period following the emplacement of the 85 E ridge. Formation of the SW-NE trending canyon in the sea floor is an evidence of strike slip movement in the same direction. This is further corroborated from the focal plane solutions of earthquakes north and south of the area. Thus the morphotectonic units mapped in this zone in the continental shelf off Orissa coast are an ideal example of a transpressional regime following the emplacement of the 85E ridge.


 

 

Airborne Magnetic Dat A Source of Subsurface Geological Information for Uranium Exploration:A Few Case Studies over some Proterozoic Sedimentary Basins of India.

 

M. Bandyopadhyay
Atomic Minerals Directorate for Exploration and Research.Department of Atomic Energy, Hyderabad 500016.

Abstract

 

   Airborne survey was first used in India by AMD in the year 1956 for exploration of uranium. At the initial stage it was aimed to locate near surface Uranium anomalies. Acquisition of magnetic data along with radiometric data started from the year 1972. So far, AMD has acquired valuable aeromagnetic data amounting to nearly 5.2 lakh sq km area, spread over important Uranium Provinces of India. Quality of the aeromagnetic data has improved through the ages with the application of new technologies. The most recently collected aeromagnetic data collected by heliborne survey over parts of Vindhyan basin accurately sampled subtle magnetic anomalies at the basement.

 

   Aeromagnetic survey is an effective tool for studying basement features of Middle Proterozoic sedimentary basins. Nonmagnetic (low susceptibility) sediments overlying the basements of distinctly higher susceptibility makes this possible. Study of Aeromagnetic maps over Bhima, parts of Chhattisgarh, Bijawar, Gwalior and Vindhyan basins has deciphered many important geological features viz. basement morphology, movements of basement blocks along faults and continuation of fracture/fault associated with higher value of uranium below the sediment. AMD will continue to cover more and more areas by airborne surveys in future days to meet the exploration challenges imposed on it with better quality airborne multi parameter geophysical data.

 

 

 

BOOK REVIEW : Geology of India ( 2010 Edition).

 

M. Ramakrishnan and R. Vaidyanadhan
Authors : M. Ramakrishnan and R. Vaidyanadhan (Vol.1)
R. Vaidyanadhan and M. Ramakrishnan (Vol.2)
(Price: Rs. 1500/- both volumes put together)
Geological Society of India
P.B.No.1922, Gouripuram P.O., Bangalore 560 019

 

 

 

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