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Raul - Condestable |
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Peru |
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Cu Au Ag
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Super Porphyry Cu and Au
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IOCG Deposits - 70 papers
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The Raúl-Condestable Cu-Au-Ag deposit, located at around 90 km south from Lima, in coastal Peru, on the western side of the Middle Cretaceous to Tertiary, 107 to 37 Ma Peruvian Coastal Batholith.
The immediate country rock comprises Late Jurassic to Lower Cretaceous shallow water volcano-sedimentary sequence, representing a series of superposed volcanic edifices, all of which are crosscut by intrusions of the Peruvian Coastal Batholith.
The >6 km thick, Late Jurassic to Early Cretaceous volcano-sedimentary host sequence dips at around 40° WSW. All magmatic rocks in the deposit have a typical arc geochemistry. The uppermost unit at the deposit is a 2 to 3 km thick dacite-andesite volcanic suite intruded by a sub-volcanic quartz-diorite porphyry sill-dyke complex which follow NE, NNE and NW trends. The latter dip at 35 to 45°, while the others are near vertical.
Most of the sills intrude the upper part of the underlying unit which comprises a Lower Cretaceous, shallow water, volcano-sedimentary sequence, composed of basalt-andesite, pyroclastic, tuff, sandstone, shale and limestone. The main and uppermost sill forms a laccolithic structure up to 500 to 600 m in thickness and strike extent of 4 km within this same underlying unit. The centre of the porphyritic sill-dyke complex is successively cut by two tonalitic intrusions, the first of which forms a 1600x300 m stock with minor apophyses, while the second is a 200x30 m dyke cutting the first tonalite. A late, regional, NW trending and east-dipping dolerite dyke swarm crosscuts all of the intrusions, the volcano-sedimentary sequence, and the IOCG mineralisation.
The Lower Cretaceous, shallow water, volcano-sedimentary sequence is progressively underlain by a 1.5 km thick detrital sequence of quartzite, sandstone, shale and rare limestone and a lower, >500 m thick, volcano-sedimentary unit composed of basalt-andesite, tuff, shale and sandstone.
Age dating suggest the quartz-diorite porphyry sill-dyke complex and the uppermost dacite-andesite volcanic dome formed at around 116.5 Ma, whereas the two tonalite phases were intruded at around 115 Ma. Hydrothermal titanite of the IOCG mineralisation has been dated at 115.2 ±0.3 Ma coeval with the tonalitic magmatism and only slightly younger than the overlying volcanic edifice represented by the uppermost unit.
The IOCG mineralisation surrounds the first tonalite stock and is mainly developed within the volcano-sedimentary sequence, replacing porous (tuffs, pyroclastic deposits, volcanic breccias) or chemically reactive (limestone) beds to form replacement mantos and veins containing chalcopyrite-pyrite-pyrrhotite-magnetite with actinolite. The deposit forms mantos and disseminations around feeder veins. The feeder veins trend NE, NW and E-W and are broadly
perpendicular to the bedding.
The veins cut the host sequence from the detrital sequence to the upper dacite-andesite volcanic suite, the quartz-diorite porphyry and locally the first tonalite.
The ore comprises a chalcopyrite-pyrite-pyrrhotite-magnetite assemblage, where magnetite is often massive. A broad correlation has been observed between Cu, Ag, and Au grades. Associated minor elements include Co, Mo, Zn, and Pb.
The alteration pattern has an early biotite core cut by a quartz stockwork surrounding, but almost exclusively outside, the first tonalite. The alteration is zoned outward to actinolite ±magnetite ±chlorite ±titanite ±scapolite ±albite ±epidote. and upward to Fe chlorite + sericite assemblages. Actinolite veinlets cut the biotite alteration. Late prehnite and pumpellyite locally overprint the actinolite-albite-scapolite assemblage, while an upper distal alteration halo, consisting of hematite-chlorite (±epidote-calcite-albite) laterally surrounds the Fe chlorite + sericite and actinolite-albite-chlorite assemblages.
In detail the alteration and ore assemblages follow the following sequence: i). albite and scapolite (the Na end-member marialite); ii). Ca-amphiboles; iii). hematite-magnetite-(±quartz-feldspar-sericite-chlorite), with widespread pseudomorphic replacement of hematite by magnetite; iv). main sulphide stage started with minor molybdenite, then pyrrhotite, pyrite with minor marcasite, and ended with chalcopyrite, Au, and minor sphalerite and galena ±quartz-chlorite-sericite (Au occurs as inclusions within chalcopyrite); v). late minor carbonate-sulphide stage with calcite-pyrite-sphalerite-galena-marcasite-bravoite-chalcopyrite.
Zoning both in veins and mantos from proximal to distal relative to the feeder veins (but also late to early within the paragenetic sequence) is chalcopyrite to pyrite, pyrrhotite and magnetite.
The accumulated production + reserves of the Raul-Condestable deposits to 2006 was >32 Mt @ 1.7% Cu, 0.3 g/t Au, 6 g/t Ag.
The most recent source geological information used to prepare this decription was dated: 2005.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Chen H, 2010 - Mesozoic IOCG Mineralisation in the Central Andes: an Updated Review: in Porter T M, (Ed), 2010 Hydrothermal Iron Oxide Copper-Gold and Related Deposits: A Global Perspective PGC Publishing, Adelaide v.3 pp. 259-272
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de Haller A and Fontbote L, 2009 - The Raul-Condestable Iron Oxide Copper-Gold Deposit, Central Coast of Peru: Ore and Related Hydrothermal Alteration, Sulfur Isotopes, and Thermodynamic Constraints: in Econ. Geol. v104 pp 365-384
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de Haller A, Corfu F, Fontbote L, Schaltegger U, Barra F, Chiaradia M, Frank M and Alvarado J Z, 2006 - Geology, Geochronology, and Hf and Pb Isotopic Data of the Raul-Condestable Iron Oxide-Copper-Gold Deposit, Central Coast of Peru: in Econ. Geol. v101 pp 281-310
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Injoque J, 2002 - Fe Oxide-Cu-Au Deposits in Peru: An Integrated View: in Porter T M (Ed), 2002 Hydrothermal Iron Oxide Copper-Gold & Related Deposits: A Global Perspective PGC Publishing, Adelaide v.2 pp. 97-113
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Vidal C E, Injoque-Espinoza J, Sidder G B, Mukasa S B 1990 - Amphibolitic Cu-Fe skarn deposits in the central coast of Peru: in Econ. Geol. v85 pp 1447-1461
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Williams P J, Barton M D, Johnson D A, Fontbote L, de Haller A, Mark G, Oliver N H S and Marschik R, 2005 - Iron oxide copper-gold deposits: Geology, space-time distribution and possible modes of origin: in Hedenquist J W, Thompson J F H, Goldfarb R J and Richards J P (Eds.), 2005 Economic Geology 100th Anniversary Volume, Society of Economic Geologists, Denver, pp 371-405
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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