Radiogenic Heat Production and Heat Flow in Talca Basin (35.5°S), Central Chile

Abstract

The aim of this work is to determine the influence of the Radiogenic Heat Production (RHP) of lithospheric rocks in the heat flow coming up from rock basement, beneath Talca basin, located between Coastal Range and Andean Range. The RHP is estimated based on the content of Radiogenic Heat Production Elements (RHPEs: U, Th and K) of lithologies, which compose the lithosphere beneath Talca. The concentration of RHPEs is measured in distributed Mesozoic and Cenozoic outcropping rocks, using a portable gamma ray spectrometer. The RHPEs for middle, and lower crust are estimated by extending beneath the Talca basin, the Paleozoic coastal metamorphic complex, and by inferring the presence of granulites, respectively. Physical properties of lithospheric mantle are taken from petrological and geophysical studies. The thermal structure of lithosphere is performed in a 2-D lithospheric cross-section, with a finite elements modelling of heat transfer in solids with COMSOL multiphysics. The model was performed considering the RHP as a heat source of each lithospheric unit, temperature as a thermal boundary conditions at the top and bottom of lithosphere, and its architecture, which is determined from an upper crust deformation model, and geophysical data from deeper lithospheric units. The estimated heat flow, which reaches the basin floor, from rock basement in Talca basin is 62-65 mW/m2.