Abstract Mesozoic and Cenozoic ore deposits in the. Chilean Andes between La Serena ($30°S) and Santiago. ($34°S) include polymetallic vein, low- and ...
Mineralium Deposita (2003) 38: 234–250 DOI 10.1007/s00126-002-0307-2
A RT I C L E
Richard M. Tosdal Æ Francisco Munizaga
Lead sources in Mesozoic and Cenozoic Andean ore deposits, north-central Chile (30–34S)
Received: 21 June 2001 / Accepted: 21 June 2002 / Published online: 22 August 2002 Springer-Verlag 2002
Abstract Mesozoic and Cenozoic ore deposits in the Chilean Andes between La Serena (30S) and Santiago (34S) include polymetallic vein, low- and high-sulfidation epithermal vein, skarn, porphyry copper-molybdenum and porphyry copper-gold. These deposits are associated with volcanic and plutonic complexes emplaced in eastward-migrating longitudinal arcs which formed during subduction along the continental margin of South America since the Middle Jurassic. Stratabound, but epigenetic, volcanic rock- and sedimentary rock-hosted manto deposits contain additional copper resources. Lead isotopic compositions in ore minerals from 29 deposits vary with age and geographic location, and hence with basement and host rocks. Lead in most ore deposits is derived from temporally related igneous rocks, except for the manto deposits whose lead is derived from host volcanic and sedimentary rock sequences. Lead in the ore deposits is dominated by two crustal sources. Low 207Pb/204Pb characterizes one source whereas high 207Pb/204Pb characterizes the second source. Lead isotopic compositions of Jurassic and Miocene ore minerals (206Pb/204Pb>18.50; 207 204 Pb/ Pb>15.61) lie along the average crustal growth curve. By contrast, most Cretaceous deposits have ore minerals with lower 206Pb/204Pb (
