Heat flow in Rajasthan Craton, North–Western Indian Shield and its Implications

Abstract

A synthesis and reinterpretation of surface heat flow values of the Rajasthan Craton(RC), north-western Indian Shield has been carried out. The results reveal that the q values are relatively high, varying from 52 to 96 mWm-2. Appreciable variations in the magnitude of q are found between and within its geotectonic units, but with considerable overlap of values. Paleo–Meso Proterozoic Aravalli Super Group is generally associated with high q values, varying from 52 to 67 mWm-2, with a mean value of 60 mWm-2. Values of still higher order varying from 52 to 76 mWm-2 occur in North Delhi Fold Belt of Meso–Neo Proterozoic Delhi super Group, Tusham area, which is located towards north west corner of the Delhi Fold Belt in the Trans-Aravalli Province of RC, is characterized by a very high heat flow value. This is the highest of all heat flow values so far reported for the Proterozoic terrains of the Indian Shield, which is ascribed as due both to enhanced crustal radioactivity and renewed tectonic activity beneath its region. The heat flow values reported in areas of the Delhi Super Group and Aravalli Super Group are of short wavelength, naturally these are due to shallow sources. We infer that these are mostly due to varying degrees of concentration of heat producing elements in the upper crust. There are also no evidences of major tectono-thermal events after the Neo-Proterozoic times (~600Ma) in the study area. Hence, we conclude that observed variations in heat flow do not carry thermal transients of any recent tectonic activity.