Intrusive bodies associated with the polymetallic mineralization of the Cerro León deposit, area of Cerro Tranquilo anticline, Santa Cruz: Geophysical evidence

Abstract

The geologic characteristics such as presence of basic to intermediate intrusive and subvolcanic bodies, and the mineralization with high sulfide content of the El Tranquilo anticline area are peculiar and poorly represented in the Deseado Massif. The Cerro León polymetallic deposit presents a geochemical and mineralogical signature that is different from the classic low sulfidation epithermal model, characteristic of the Deseado Massif. Aeromagnetic data from the El Tranquilo anticline area allow recognizing a subcircular anomaly that is interpreted as a buried intrusive body of approximately 9 km of diameter, which underlies the El Tranquilo Group and Roca Blanca Formation. Its depth is estimated in 1,400 m. This intrusive body generated the doming of El Tranquilo anticline, and its associated regional radial fractures. The presence of small intrusive and subvolcanic bodies or apophyses fed by the higher intrusive body, interpreted from magnetic anomalies of smaller diameter and higher gradient, are confirmed by drilling. The main veins of the Cerro León deposit are located on top of the buried intrusive and subvolcanic bodies. This, plus the high sulfide content and geochemical and mineralogical signature of the veins, suggests that the mineralization is genetically associated to the intrusive bodies and allows the use of this model as a prospecting tool for this type of deposits.