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 port ion of the Sierra Grande de San Luis, San Luis Province, Argentina. A 26 mG al 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 mode ls based on more than 300 gravimetric, magnetometric, and geological field measurements and observations suggest that the mafic-ultramafic belt of Sie rra Grande de San Luis continues south of San Luis. The low magnitude of th e terrestrial magnetic field anomalies indicates that these mafic-ultramafi c rocks do not carry a base metal sulfides (BMS) mineralization. The Charlo tte gravimetric, anomaly is generated by a belt of mafic-ultramafic rocks w hose amplitude is comparable with that responsible for the Virorco-Las Agui las gravimetric anomaly. (C) 2001 Elsevier Science Ltd. All rights reserved .