Description
A previously undescribed mining district located in the Sierra de Pinta of Baja California, Mexico has been investigated using geological, geochemical, and geophysical methods. Silver, lead, gold and zinc occur in many epithermal veins throughout the area. Argentiferous galena, sphalerite, pyrite, and chalcopyrite in quartz-carbonate gangue are the typical ore minerals. Post-Miocene veins occur as fault and fracture fillings in Paleozoic metamorphic and Late Miocene volcanic rocks. Geological mapping has been used to locate major fault and fracture filling vein systems. Geochemical trace element studies have been used to locate higher-than-normal silver, gold, lead, and zinc in arroyo sediments which have resulted by weathering of mineralized veins. Three areas of higher-than-normal trace element data were investigated using self potential, resistivity, and induced polarization geophysical methods. Data from these field methods failed to reveal new ore grade deposits in the Sierra de Pinta, although the presence of low grade mineralization was indicated. Recommendations have been made in order to guide future exploration and mining activities in the area. The Sierra de Pinta mineralized district is part of a northwest trending regional zone of Late Cenozoic silver-gold mineralization that extends from central Mexico into the southwestern United States.
