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Lithogeochemistry of the Collahuasi porphyry Cu-Mo and epithermal Cu-Ag (-Au) cluster, northern Chile; Pearce element ratio vectors to ore

Esteban Urqueta, T. Kurt Kyser, Alan H. Clark, Clifford R. Stanley and Christopher J. Oates
Lithogeochemistry of the Collahuasi porphyry Cu-Mo and epithermal Cu-Ag (-Au) cluster, northern Chile; Pearce element ratio vectors to ore
Geochemistry - Exploration, Environment, Analysis (February 2009) 9 (1): 9-17

Abstract

Lithogeochemical vectors to ore-bodies are obscured by the variety of lithological units and the alteration events that have affected them. In the magmatic-hydrothermal context, Pearce element ratio (PER) analysis can be a cost-effective lithogeochemical technique that identifies and eliminates non-hydrothermal sources of variation, thus permitting the definition of material transfer related only to hydrothermal alteration. Dedicated PER diagrams for mafic and felsic lithologies in the world-class porphyry Cu-Mo and epithermal Cu-Ag (-Au) cluster of the Collahuasi district, I Region, northern Chile, effectively model background variability and discriminate between fresh or propylitically altered rocks and those with a hydrolytic alteration overprint. Furthermore, PER diagrams allow for the definition of an alteration index (AI) that quantifies the degree of metasomatic exchange during hydrolytic alteration of a particular rock. Plots of different PER values against the AI show that potassium enrichment during hydrolytic alteration was followed by potassium, calcium and sodium depletion as a result of the destruction of feldspars during sericitic and later argillic alteration. Although PER plots record no mass transfer processes involving major elements during propylitic alteration, the integrated AI for both mafic and felsic units spatially defines the major alteration centres within the district.


ISSN: 1467-7873
EISSN: 2041-4943
Serial Title: Geochemistry - Exploration, Environment, Analysis
Serial Volume: 9
Serial Issue: 1
Title: Lithogeochemistry of the Collahuasi porphyry Cu-Mo and epithermal Cu-Ag (-Au) cluster, northern Chile; Pearce element ratio vectors to ore
Affiliation: Queen's University, Department of Geological Sciences and Geological Engineering, Kingston, ON, Canada
Pages: 9-17
Published: 20090201
Text Language: English
Publisher: Geological Society Publishing House, London, United Kingdom
References: 23
Accession Number: 2009-041019
Categories: Geochemistry of rocks, soils, and sedimentsEconomic geology, geology of ore deposits
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. geol. sketch map
S21°00'00" - S20°55'00", W68°45'00" - W68°34'60"
Secondary Affiliation: Acadia University, CAN, CanadaAnglo-American, GBR, United Kingdom
Country of Publication: United Kingdom
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data from GeoScienceWorld, Alexandria, VA, United States. Reference includes data from The Geological Society, London, London, United Kingdom
Update Code: 200922
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