Conductive heat flow in the Godavari sub-basin (Pranhita- Godavari valley), Indian shield and its significance

The Godavari sub-basin (GSB) is a part of the Gondwana Pranhita – Godavari Valley (PGV) of the Indian Peninsular Shield, which is a major NW-SW lineament where sediments from Neoprotrozoic to Mesozoic are present. The objective of this paper is three fold viz ; i) an examination and analysis of available measured heat flow values(HFU) of the GSB for hydro-geological perturbations and obtain the most probable true magnitude of conductive heat flow (CHF) value, in cases wherever it is possible, ii) to decipher the thermal characteristics of the GSB through a comparison of its CHF values with the other available heat flow data in its surrounding region of the Indian Shield, and iii) to infer the main deep thermal characteristics of the GSB through an examination of the results so obtained and the inferences from some reported geo-data of the GSB and PGV. Based on our analysis we obtain; i) that the CHF values at three locations of the NW part of the GSB viz; Indaram, Godavarikhani and Bellampalli areas are 50, 52, and 49 mWm -2 respectively ,and ii) that the average CHF of the GSB is of the same order as the average HFU for the Chandrapur ,a NE sub-basin of the PGV ( 51mWm -2 ) and the Wardha – Yavatmal Deccan Trap region ( Av = 52mWm -2 ), below which Gondwana sediments, likely extension of the PGV Gondwana rocks ,do occur. The CHF values of the GSB are similar to those that are reported for Proterozoic Bastar Craton, which lies towards NE of GSB and also similar to Mailaram high which is a large outcrop of Archaean- Proterozoic group of rocks in the SE sector of the GSB. Available data on Chemical analysis of thermal waters of the area showed their meteoric origin and association with sedimentary rocks and non-magmatic sources. Based on these observations, presence of cooling magmatic bodies within the crust of GSB and a shallow Moho below it are strongly ruled out. Available geo-data (geological, gravity, seismic etc.) of GSB are in conformity with these inferences.