Gold Provenance in placers from Pureo area, southern Chile coastal cordillera, and their relationship with paleozoic metamorphic rocks
Author
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Becerra, Pablo
Author
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Sánchez Alfaro, Pablo Víctor Miguel
Author
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Piquer, José
Author
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Plissart, Gaëlle
Author
dc.contributor.author
Garroz, Belén
Author
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Kunstmann, Daniela
Admission date
dc.date.accessioned
2022-12-20T18:37:49Z
Available date
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2022-12-20T18:37:49Z
Publication date
dc.date.issued
2022
Cita de ítem
dc.identifier.citation
Minerals 2022, 12, 1147
es_ES
Identifier
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10.3390/min12091147
Identifier
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https://repositorio.uchile.cl/handle/2250/189897
Abstract
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Southern Chile placer gold deposits have been known and exploited since Spanish colonial times. Despite this, precise knowledge about their origin is scarce. This work aims to identify possible primary sources of the gold in the Pureo placers by studying the morphological and chemical characteristics of gold particles according to their spatial distribution. The former was determined by measurements and classification under a binocular microscope, allowing us to acquire a set of parameters related to the amount of transport that had affected the samples. The microchemical characteristics were determined by studying gold particles using optical microscopy, scanning electron microscopy (SEM) and electron microprobe (EMPA), where the native gold composition (in terms of major and minor elements) and the suite of mineral inclusions were obtained. The results regarding morphological characteristics suggest a low amount of transport from a primary source (<15 km). Microchemical data from gold particles indicate two compositional sub-populations, distinguished in both native gold composition (<15 Ag wt% with up to 4 Hg wt% and >15 Ag wt% with Hg bellow 1 wt%) and mineral inclusions (pyrite-galena rich and arsenopyrite rich, respectively), indicating two different primary gold sources. These results suggest a local origin of gold in the Coastal Cordillera, where the possible primary sources are associated with (i) massive sulfide deposits present in Paleozoic-Triassic metamorphic rocks and (ii) hydrothermal deposits associated with more recent Cenozoic intrusive activity. These conclusions have implications for the exploration of new placer deposits and of gold-bearing hypogene deposits (e.g., metamorphosed VMS deposits) in unexplored zones of southern Chile Coastal Cordillera.
es_ES
Patrocinador
dc.description.sponsorship
FNDR (Fondo Nacional de Desarrollo Regional, Los Rios, Chile) project "Transferencia Programa de Apoyo a la Pequena Mineria"
ANID-FONDECYT 1201219
11181048
Amira Global project grant P1249
es_ES
Lenguage
dc.language.iso
en
es_ES
Publisher
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MDPI
es_ES
Type of license
dc.rights
Attribution-NonCommercial-NoDerivs 3.0 United States