The epithermal gold-silver deposit of Choquelimpie

The Choquelimpie gold-silver deposit is located at an elevation of 4,860 m above sea level, 115 km due east of Arica in northern Chile. A 5,500-metric-ton/day open-pit mine-heap leach operation was brought on stream in 1988 by the Sociedad Contratual Minera Vilacollo, whose shareholders are Shell Chile, Westfield Minera, and Citibank. The deposit is located near the Arica bend of the South American continent, where the earth's crust has a thickness of more than 70 km. It lies in a belt of calc-alkalic to alkali-calcic Miocene to Recent volcanism which runs parallel to the Pacific coast and contains a series of volcanic-hosted precious metal deposits. These have been worked in Peru, Chile, and Bolivia since the time of the Spanish conquest, usually for Ag but also with locally important Au values. These deposits are characterized by Ag-Au-Pb-Zn. The volcano hosting the mineralization isa subalkalic stratovolcano of late Miocene age; a late magmatic event has been dated at 6.60 q- 0.20 Ma. The volcano is located at the intersection of a major N 60 ø E-trending lineament with a N 35 ø E fault, active from the late Miocene to the Recent. The volcano consists of dacitic and andesitic volcanic flows and breccias and is intrude