HEAT-FLOW IN THE BASTAR CRATON, CENTRAL INDIAN SHIELD - IMPLICATIONS FOR THERMAL-CHARACTERISTICS OF PROTEROZOIC CRATONS

Measurements of surface heat flow density in various lithologies from the central parts of the Proterozoic Bastar Craton of the central Indian Shield have yielded heat flow values ranging from 51 to 64 MW m-2, with a mean value of 56 mW m-2 (standard deviation = +/- 6.1 MW m-2). These values are considerably higher than in the Archaean and Archaean to Early Proterozoic cratons of many Precambrian shields, but are compatible with the heat flow data from the Proterozoic Gawler Craton, central Australian Shield. It is inferred that (1) the contrast in surface heat flow between the Archaean and Proterozoic cratons is a consequence of the difference in the radiogenic heat production in their upper (10-20 km thick) crustal layers, and (2) the Proterozoic cratons, as these could also have enclaves of basic Archaean rocks, show a wide range of surface heat flow values controlled mainly by the varying amounts of upper crustal radiogenic heat source.