Radiogenic heat production in granitoids from the Sierras de Córdoba, Argentina

Abstract

One of the most important processes of heat generation from the Earth's interior is the radioactive decay of isotopes. The main hosts of the major radiogenic elements U, Th and K in the crust are granitoids. The Sierras de Córdoba are formed of dissimilar granitic intrusions emplaced by a series of magmatic events that occurred during the Paleozoic. The different granitoids are classified as A-type, I-type, and S-type, and there is also a magmatic expression corresponding to the Famatinian period which exhibits TTG-type characteristics. In this work, the geochemical concentrations of the radiogenic elements of the granitic intrusions making up the Sierras de Córdoba were compiled in a single database. The radiogenic heat production of the Sierras de Córdoba granitoids was evaluated, making this the first study of radiogenic heat generation in the area. The radiogenic heat production showed variability for the different events, with the highest values found in Achalian magmatism and early Carboniferous magmatism, which are represented by A-type granitoids. The Capilla del Monte pluton has the highest heat production rate, with a value of 4.54 ± 1.38 µW/m3. The lowest values were found in the TTG-type granitoids and in the S-type granitoids, all of which belong to the Famatinian magmatic event. The range of values for this magmatic event goes from 0.26 ± 0.05 µW/m3 for the San Agustin pluton to 1.19 ± 0.50 µW/m3 for the La Playa pluton. An empirical ternary model is presented for the Sierras de Córdoba that involves the concentrations of the elements U, Th and K, and the radiogenic heat production, with a distinction for the petrogenetic types according to the S-I-A-M classification. The thermal manifestations located on the Capilla del Monte pluton could be related to the radioactive heat generation of the intrusion, involving both the neotectonic activity of the area and the radiogenic heat production. The results provide new opportunities for studying temperature variation within some of these intrusions and to evaluate the geothermal potential of the granitoids of Córdoba.