Journal of Geological Society of India (Online archive from Vol 1 to Vol 78)

S. C. Jain ¹, D. B. Yedekar ¹, K. K. K. Nair ¹

Affiliations
1 Geological Survey of India, Central Region, Nagpur-440 010, IN

Abstract

The paper records the occurrence of mylonites along a major ductile shear zone in Nagpur-Bhandara- Balaghat-Bilaspur-Korba region of Central India, now named as Central Indian Shear/Suture zone (C.I.S.). The main shear zone extends from SSE of Nagpur to south of Korba over a distance of 500 km with a sinuous E-W trend and subvertical to steep northerly dips. Its northern branch extending in ENE direction from Amarkantak to north of Nagai has been named as the Tan Shear. The CIS separates the high-grade Sausar metasediments with a zone of granulites to its north from the dominant low-grade volcanogenic sequences to its south.

Bouguer gravity trends over Central India suggest that the CIS probably extends eastwards into the Singhbhum shear zone of Bihar-Orissa and westwards, into the Delhi-Aravalli shear zone in Rajasthan.

Keywords

Central Indian Shear Zone, Precambrian, Central India.

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Dewashish Kumar ¹, N. S. Krishnamurthy ¹, Shekeel Ahmed ¹, S. C. Jain ¹, R. L. Dhar ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

Mise-a-la-masse technique has been applied to map water filled fracture1 struck in bore wells in a small watershed near Hyderabad. The area consists of hard crystalline rock mainly granite where groundwater is mostly tapped from iractured rock. In the watershed, 25 wells have been drilled fairly distributed over the area on the basis of results of Vertical Electrical Soundings (VES) to study the groundwater conditions in the weatheredffractured aquifer system. Mise-a-la-masse and Spontaneous Polarization (SP) investigations were carried out at five out of these 25 sites, to delineate the lateral extension of fractures. The anomalies are clearly indicative at four locations and some indication is seen at the fifth location. Two bore wells drilled on the basis of these results have encountered fractures at the same depth as at the experimental site. It is concluded that mise-a-la-masse technique supplemented with S.P. investigations could be helpful in delineating the extension of fractures.

Keywords

Mise-a-la-Masse, SP, Electrical Mapping, Fractures in Hard Rock, Maheshwaram Watershed, Andhra Pradesh.

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V. S. Singh ¹, S. C. Jain ¹, T. V. Rao ¹, M. N. Rao ¹, B. C. Negi ¹

Affiliations
1 National Geophysical Research Institute, Hyderabad - 500 007, IN

Abstract

Shales/limestone, which are devoid of primary porosity, often act as the potential aquifers when they are fractured and/or weathered. An integrated approach employing photogeologicil, hydrogeological and geophysical investigations has now been attempted to delineate groundwater potential zones in such shaley limestone terrain at the southern part of Chandrapur District of Maharashtra. This cost-effective approach, which was focussed at sites delineated from aerial photo interpretation has helped in drilling of good yielding wells in an otherwise unpromising shaley limestone terrain.

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