Geology, Geochronology, and Hf and Pb Isotope Data of the Raul-Condestable Iron Oxide-Copper-Gold Deposit, Central Coast of Peruстатья из журнала
Аннотация: Raúl-Condestable is a >32 million metric ton (Mt) iron oxide-copper-gold (IOCG) deposit located on the Peruvian coast, 90 km south of Lima.The ore occurs as veins, replacement "mantos," and disseminations consisting of a chalcopyrite-pyrite-pyrrhotite-magnetite-amphibole mineral association.The geology of the studied area comprises a series of superposed volcanic edifices of Late Jurassic to Early Cretaceous age, which are part of a larger volcanic island to continental arc system.Particularly good exposures of the tilted host sequence allow the mapping of the Raúl-Condestable IOCG deposit in a nearly complete oblique cross section, from its associated volcanic edifice down to a paleodepth of about 6 km.U-Pb zircon ages indicate that in the deposit area felsic magmatic activity took place between 116.7 ± 0.4 and 114.5 ± 1 Ma, defining a new Raúl-Condestable superunit, the oldest so far, of the Peruvian Coastal batholith.This superunit is located west of the main part of the batholith and includes a dacite-andesite volcanic dome and a subvolcanic quartz-diorite porphyry sill-dike complex that were emplaced at 116.7 ± 0.4 and 116.4 ±0.3 Ma, respectively, followed by tonalite stocks and dikes emplaced between 115.1 ± 0.4 and 114.5 ± 1 Ma.All these rocks contain hornblende and/or biotite but no pyroxene and correspond to silica-and waterrich magmas following a calcic differentiation trend.Hf isotope data on zircons (εHf(115 Ma) = 5.2-7.5) and Pb isotope data on whole rock, combined with lithogeochemical results, suggest that magmas were generated by partial melting of the upper mantle, enriched through hydrous metasomatism and/or melting of subducted pelagic sediments.The lack of zircon inheritance suggests that there was no direct involvement of continental crust.The Raúl-Condestable IOCG deposit is connected in space and time with the magmatism of the Raúl-Condestable superunit.The mineralization was emplaced in the core of the dacite-andesite volcanic dome at a paleodepth of 2 to 3 km, surrounding two tonalitic intrusions formed at 115.1 ± 0.4 and 114.8 ± 0.4 Ma.The U-Pb age of hydrothermal titanite from IOCG veins at 115.2 ± 0.3 Ma indicates that the mineralization was coeval with (or more probably just followed) the emplacement of the tonalites.Re-Os geochronology on molybdenite did not yield reliable ages due to apparent Re loss.Copper ore is associated with a zoned alteration pattern, which surrounds the tonalite intrusions.It consists of a core of biotite alteration and quartz stockwork,
Год издания: 2006
Авторы: Antoine de Haller, Fernando Corfú, Lluı́s Fontboté, Urs Schaltegger, Fernando Barra, Massimo Chiaradia, Martin Frank, Julio Zúñiga Alvarado
Источник: Economic Geology
Ключевые слова: Geological and Geochemical Analysis, earthquake and tectonic studies, Geochemistry and Geologic Mapping
Другие ссылки: Economic Geology (HTML)
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Том: 101
Выпуск: 2
Страницы: 281–310