Heat Flow Studies in India: An Update

Abstract

The geothermal study in India was initiated in 1962 and in the last six decades it grew in concurrence with the international programmes of geothermal study on several fronts, such as, characterizing heat flow for the major geological units; measuring the thermal conductivity of crustal rocks at ambient and elevated temperatures; arriving at the best mathematical model of thermal conductivity from modal mineralogy; calculating radiogenic heat production for the major rock formations; modeling crustal and sub-crustal thermal structure for the stable regions; calculating mantle temperature constrained with seismic velocities and mantle xenoliths; assessing geothermal energy potential regions and using geothermal observations to estimate past climate changes. Systematic heat flow, thermal conductivity, heat production, and thermal modelling carried out during this period of time led to the refinement of classical thermal models of the continental crust, i.e., from linear-step-exponential heat production model based on linear relationship, to realistic heat production models based on regional geology and regional crustal structure from geophysical studies. In many cases, such studies have also helped in the exploration of geothermal energy potential regions, geoengineering works and deciphering past climate changes. Future research goals include to study (i) crustal and upper mantle thermal structure in the unexplored geological provinces, active tectonic zones, sedimentary basins, and hot spring areas of the Indian sub-continent, (ii) thermal structure in the adjoining oceanic regions, occurrence of potential geothermal energy resources, (iii) thermal properties of rocks at elevated temperature and their implications in refining lithospheric thermal model, (iv) linkage between geothermal and meteorological records for past climate change.