| Abstract |
The Gondwana coalfields in India are a warehouse of fossil fuel energy sources. The coal bearing formations are deposited in deep subsiding basinal structures confined to half-grabens. The Talchir, Barakar, Barren Measures and Raniganj formations were deposited in this subsiding basin with basement rocks separated by faulted margins. The contact of Gondwana rocks with the basement is marked by faulted margins, while the downthrown side represents a basin of deposition where a huge pile of sediments were deposited. The cumulative thickness of the sedimentary pile in the basins varies from 1200 m to 3000 m, depending on the Gondwana formations deposited. Sedimentary rocks are mostly permeable, facilitating deep percolation and lateral movement of groundwater. The water percolating to deeper levels collects heat during the subsurface movement and follows the conduit provided by fault zones for upward movement toward the surface, giving rise to hot springs along Gondwana margins. The hot springs at Tatapani in the Surguja district (52°C –97°C), Anhoni Samoni in the Hoshangabad district (45°C –54°C), and Managuru (40°C-42°C) in the Khammam district are located along the fault controlled Gondwana margins. During drilling, hot water was encountered in the Mand –Raigarh coalfield in the Raigarh district and the Kothagudem coalfield in the Khammam district. These hot springs are of intermediate enthalpy and may be utilized for direct heat schemes, particularly during winter months. The need to explore the Gondwana coalfields for geothermal energy resources for site specific direct use and electricity generation is emphasized in this paper. The fault margins of the Gondwana basins form a suitable locus for exploration. Geophysical surveys associated with drilling along the intersecting lineaments are possible sites for geothermal exploration. |