Vertical distributions of uranium, thorium and potassium and of volumetricheat production rates in the sediments of the Sao Francisco Basin, CentralBrazil

Uranium, thorium and potassium measurements and volumetric heat production rate calculations were made in Bambui Group Neoproterozoic sedimentary rock s from the Sao Francisco Basin, central Brazil. The measurements were made from drilling cuttings from two deep wells drilled near the cities of Alvor ada do Norte, northeast Goias State, and Montalvania. north of Minas Gerais State. The obtained results allowed the construction of the vertical profi les depicting the abundances of heat generating elements, of the heat produ ction rate and of U/Th, U/K and Th/K ratios in these sediments. These profi les. which reflect both the lithology and the sediment history, are used to interpret some aspects of the Bambui Group sedimentation sequence. (C) 200 1 Elsevier Science Ltd. All rights reserved.