Analisis Espectral De Anomalias Magneticas Para El Calculo De La Isoterma De Curie: Una Metodologia Para Estimar El Flujo Termico Cortical En Las Provincias De San Juan Y La Rioja, Argentina

Spectral analysis of magnetic anomalies to calculate Curie-temperature isotherm: A methodology to estimate crustal heat-flow for San Juan and La Rioja provinces, Argentina. A method to estimate the depth extent of magnetic sources was applied to the<br>magnetic anomalies from our terrestrial magnetic data base. The analysed region involving the Precordillera Cuyana and the Sierras Pampeanas of San Juan and La Rioja, including the Famatina System. The top (Z~) and bottom (Zb) boundaries of the magnetized crust were calculated from power-density spectra of the total-field anomalies on 2-D ninety windows with 1 .5°xl .5° size. The depths obtained for the bottom of magnetized crust are assumed to correspond to Curie point depths. The values thus obtained for the Precordillera range between 29 and 40 km, whereas for the Sierras Pampeanas, in the Sierra de Pie de Palo, and other mountain chains along the Bermejo-Desaguadero lineament, such depth ranges between 20 and 35 km. From Curie point depths we have proposed a map of heat flow in the studied region. The patterns of heat flow are distinct on the Precordillera and on the Pampean region. The Precordillera geologic province is characterized by low heat flow and deep Curie depths, whereas the Sierras Pampeanas geologic province is characterized by high heat flow and shallow Curie depths. A significant heat flow extending in Northeast-Southwest direction seems to be directly related to Juan Fernández Ridge trace.