Curie isotherm in Central Chile: gradient and geothermal flow analysis in the continental zone

Abstract

This study explores the relationship between magnetometry and thermodynamics in heat transfer within the Earth's crust in central Chile. The radially averaged power spectrum analysis of magnetic data was used to determine the Courie point depth, from the city of La Serena (~30°S) to San Fernando (~34.5°S), and from the Andes Mountains (~70.5°W) to approximately 82°W. Offshore, the Curie isotherm shows an average depth of 22 km and is tentatively correlated with the Juan Fernández Ridge. Inland, significant differences are observed; on the one hand, the Curie isotherm reaches shallower depths, averaging 12 km from Ovalle to Illapel; on the other hand, a deeper zone, at approximately 39 km depth, is identified northeast of Valparaíso. An empirical equation is then employed to calculate the thermal conductivity of the rocks and determine the geothermal heat flow. The average geothermal gradient in the continental region of central Chile is 20°C/km, with a maximum of 45°C/km in the locality of Canela. In the Metropolitan Region of Santiago, the average heat flow is 50 mW/m², with a maximum of 57 mW/m² in the commune of Paine. The results obtained are consistent with a previous radiogenic study in the Santiago basin, suggesting that the method used in this research constitutes a novel technique that can be replicated to other regions of the country. The information provided in this contribution can be utilized for the design of geothermal energy systems and to improve the understanding of geological processes in the region.