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Shallow polymetallic and precious metal mineralization associated with a Miocene diatreme-dome complex : the Colquijirca district in the Peruvian Andes

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Defense Thèse de doctorat : Univ. Genève, 2006 - Sc. 3779 - 2006
Collection Terre et Environnement; 64
Abstract Ore characterization based mainly on microscopic and microanalytical methods allow to discriminate two type of epithermal mineralization in the Colquijirca district, central Peru: disseminated high sulfidation epithermal Au-(Ag) ores and sulfide-rich zoned cordilleran polymetallic deposits. High precision ⁴⁰Ar/³⁹Ar radiometric dating reveals that high sulfidation Au-(Ag) ores, formed from 11.9±0.07 to 11.10±0.06 Ma, predated cordilleran mineralization which formed from 10.83±0.06 to 10.59±0.06 Ma. Both systems entrained commonly strongly acidic fluids recorded by episodic precipitation of alunite derived from magmatic vapor plumes. Two end-member fluids are recognized in the Colquijirca system: a cold (<150°C) close-to-zero salinity fluid likely of meteoric origin and hot (250°C-300°C) 3-7 wt% NaCl equiv. dominantly magmatic fluid. It is postulated that the ore fluids resulted of a strong dilution of metal-bearing saline magmatic fluids with meteoric water that exchanges isotopically with host rocks.
Keywords ArgentOrGîtologieMiocèneMinéralogie
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URN: urn:nbn:ch:unige-979780
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BENDEZÚ, Ronner. Shallow polymetallic and precious metal mineralization associated with a Miocene diatreme-dome complex : the Colquijirca district in the Peruvian Andes. Université de Genève. Thèse, 2006. doi: 10.13097/archive-ouverte/unige:97978 https://archive-ouverte.unige.ch/unige:97978

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Deposited on : 2017-10-24

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