Magnetic and gravity anomalies in the Sierra del Padre and Sierra del Tala, San Luis Province, Argentina: evidence of buried mafic–ultramafic rocks

This paper presents the results of a geophysical study of the southern portion of the Sierra Grande de San Luis, San Luis Province, Argentina. A 26 mGal amplitude Bouguer anomaly (Charlone anomaly), measuring 40 km long by 7 km wide, between Sierra de los Padres and Zanjitas reflects the presence of high-density rocks located at approximately 2000 m depth. Geophysical models based on more than 300 gravimetric, magnetometric, and geological field measurements and observations suggest that the mafic–ultramafic belt of Sierra Grande de San Luis continues south of San Luis. The low magnitude of the terrestrial magnetic field anomalies indicates that these mafic–ultramafic rocks do not carry a base metal sulfides (BMS) mineralization. The Charlone gravimetric anomaly is generated by a belt of mafic– ultramafic rocks whose amplitude is comparable with that responsible for the Virorco-Las Aguilas gravimetric anomaly.