Results of some geothermal studies in Singhbhum Thrust Belt, India

Details of heat flow measurements made at Rakha and Narwapahar along the Singhbhum thrust belt (a Precambrian metamorphic belt in the peninsular shield of India) are reported. Temperatures were measured in a number of boreholes and conductivity data were obtained from about 80 core samples. Heat flow was evaluated taking anisotropy in conductivity into account. Heat flow values of 59 mW/m² and 63 mW/m² obtained at the above two places agree well with the value of 61 mW/m² previously reported for Mosabani. From the present observations, the whole Singhbhum thrust belt appears to be characterized by a uniform heat flow of about 61 mW/m² which is almost the same as the global average but much higher than the mean value quoted for shields. However, the surface heat flow is consistent with the surface radioactivity of the area. A plot of surface heat flow against surface heat generation (from the data on U, Th and K contents of the few samples now available) is well on the heat flow — heat generation line for the eastern United States reported by Roy, Blackwell and Birch (1968), which is considered characteristic of a normal continental heat flow province.