Cenozoic geology and mineral deposits of the Berenguela district, northwestern Bolivia

The Berenguela Ag-Pb-Zn-Cd district of the north-western Bolivian Altiplano was the site of episodic mid to late Tertiary deformation during basin sedimentation and explosive volcanism. Oligocene continental sedimentation produced the Berenguela Formation and the lower member of the Mauri Formation, both of which were buried by ignimbrites and volcaniclastic sediments of the Miocene upper member of the Mauri Formation. Dacitic to rhyolitic domes, lahars, and ash-flow tuffs were emplaced during middle Miocene to Pliocene time. Episodic tectonism and associated broad folding and high-angle faulting produced major unconformities in the sedimentary record. The district contains two types of base- and precious-metal deposits. Late Oligocene-early Miocene(?) cadmium-rich veins formed along fractures, and middle Miocene volcaniclastic and intrusive rocks. -from Authors