Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System

Autores
Maydagán, Laura; Franchini, Marta Beatriz; Lentz, Dave; Pons, María Josefina; McFarlane, Christopher
Año de publicación
2013
Idioma
inglés
Tipo de recurso
artículo
Estado
versión publicada
Descripción
Sulfides and sulfosalts from the porphyry, transitional, and epithermal high sulfidation stages of the Altar Cu-(Au) deposit (San Juan, Argentina) were investigated by electron microprobe, laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS), and S isotopic analysis. Compositional differences found in the trace-element content in pyrite, chalcopyrite, and enargite from different alteration zones and depths of the system have implications in the physicochemical evolution of the hydrothermal fluids and might have potential for exploration in similar porphyry-high sulfidation epithermal environments. Low contents of most analyzed trace elements were found in chalcopyrite ± pyrite from the potassic alteration, except for Zn, Sn, and Ag in chalcopyrite, and Co and Ni in pyrite. During the phyllic alteration, cooling of the fluids and a decrease of its pH (<4.5) produced the leaching and re-precipitation of the sulfides from the previous stage. The reprecipitated chalcopyrite and pyrite show micro-inclusions of Au (Ag alloys) and sulfosalts with As, Ag, V, Zn, Sn, Bi, and Sb that are interpreted to correlate with changes in the composition of the fluids. In the transitional veins and their selvages, early precipitation of bornite + pyrite and the weak kaolinite + quartz alteration envelope indicate a decrease in the temperature (<200 °C) and pH (<4) of the fluids and an increase of the fS2. This stage was followed by a sudden increase in the fO2 of the fluid and a slight decrease in the fS2, and bornite was replaced by tennantite (vein type E1). A trend toward higher fS2 favored enargite precipitation (vein type E3). Traces of Au found in tennantite and enargite therefore indicate that fluctuations in the oxidation state of the fluids promoted gold precipitation in the Altar porphyry system. Negative S isotope values (δ34S: –1.7 to –3.0‰) obtained for the sulfides and sulfosalts from the potassic, phyllic, and transitional stages at Altar are consistent with oxidizing (SO4 2– dominant) mineralizing fluids. The precipitation of sphalerite (δ34S = –4.4‰ and low concentration of FeS) and galena associated with calcite + anhydrite in late fractures (vein type 8) reflect cooling of the fluids and a slight increase of its pH at higher fO2, as the system moved to greater depths. The typical advanced argillic assemblages are not developed at the Altar porphyry deposit, indicating that fluids did not attain very low pH conditions. In contrast, enargite from the epithermal siliceous ledges located above the porphyry deposit precipitated with low pH mineral assemblages (quartz + alunite) and has a distinctive lighter δ34S value of –5.4‰, consistent with a decrease of temperature, pH, and/or an increase in the oxidation state of the fluids during its deposition. Enargite from the transitional stage veins of the porphyry deposit is enriched in Zn, Sb, Ag, and Bi, whereas enargite from the epithermal environment has much lower concentrations of trace elements, except for isolated inclusions of Au-Bi.
Fil: Maydagán, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; Argentina
Fil: Franchini, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; Argentina
Fil: Lentz, Dave . University of New Brunswick. Department of Earth Sciences; Canadá
Fil: Pons, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; Argentina
Fil: McFarlane, Christopher . University of New Brunswick. Department of Earth Sciences; Canadá
Materia
Trace Elements
Sulfides
S Isotopes
Porphyry-Epithermal
Nivel de accesibilidad
acceso abierto
Condiciones de uso
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
Repositorio
CONICET Digital (CONICET)
Institución
Consejo Nacional de Investigaciones Científicas y Técnicas
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oai:ri.conicet.gov.ar:11336/9065

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spelling Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal SystemMaydagán, LauraFranchini, Marta BeatrizLentz, Dave Pons, María JosefinaMcFarlane, Christopher Trace ElementsSulfidesS IsotopesPorphyry-Epithermalhttps://purl.org/becyt/ford/1.5https://purl.org/becyt/ford/1Sulfides and sulfosalts from the porphyry, transitional, and epithermal high sulfidation stages of the Altar Cu-(Au) deposit (San Juan, Argentina) were investigated by electron microprobe, laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS), and S isotopic analysis. Compositional differences found in the trace-element content in pyrite, chalcopyrite, and enargite from different alteration zones and depths of the system have implications in the physicochemical evolution of the hydrothermal fluids and might have potential for exploration in similar porphyry-high sulfidation epithermal environments. Low contents of most analyzed trace elements were found in chalcopyrite ± pyrite from the potassic alteration, except for Zn, Sn, and Ag in chalcopyrite, and Co and Ni in pyrite. During the phyllic alteration, cooling of the fluids and a decrease of its pH (<4.5) produced the leaching and re-precipitation of the sulfides from the previous stage. The reprecipitated chalcopyrite and pyrite show micro-inclusions of Au (Ag alloys) and sulfosalts with As, Ag, V, Zn, Sn, Bi, and Sb that are interpreted to correlate with changes in the composition of the fluids. In the transitional veins and their selvages, early precipitation of bornite + pyrite and the weak kaolinite + quartz alteration envelope indicate a decrease in the temperature (<200 °C) and pH (<4) of the fluids and an increase of the fS2. This stage was followed by a sudden increase in the fO2 of the fluid and a slight decrease in the fS2, and bornite was replaced by tennantite (vein type E1). A trend toward higher fS2 favored enargite precipitation (vein type E3). Traces of Au found in tennantite and enargite therefore indicate that fluctuations in the oxidation state of the fluids promoted gold precipitation in the Altar porphyry system. Negative S isotope values (δ34S: –1.7 to –3.0‰) obtained for the sulfides and sulfosalts from the potassic, phyllic, and transitional stages at Altar are consistent with oxidizing (SO4 2– dominant) mineralizing fluids. The precipitation of sphalerite (δ34S = –4.4‰ and low concentration of FeS) and galena associated with calcite + anhydrite in late fractures (vein type 8) reflect cooling of the fluids and a slight increase of its pH at higher fO2, as the system moved to greater depths. The typical advanced argillic assemblages are not developed at the Altar porphyry deposit, indicating that fluids did not attain very low pH conditions. In contrast, enargite from the epithermal siliceous ledges located above the porphyry deposit precipitated with low pH mineral assemblages (quartz + alunite) and has a distinctive lighter δ34S value of –5.4‰, consistent with a decrease of temperature, pH, and/or an increase in the oxidation state of the fluids during its deposition. Enargite from the transitional stage veins of the porphyry deposit is enriched in Zn, Sb, Ag, and Bi, whereas enargite from the epithermal environment has much lower concentrations of trace elements, except for isolated inclusions of Au-Bi.Fil: Maydagán, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; ArgentinaFil: Franchini, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; ArgentinaFil: Lentz, Dave . University of New Brunswick. Department of Earth Sciences; CanadáFil: Pons, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; ArgentinaFil: McFarlane, Christopher . University of New Brunswick. Department of Earth Sciences; CanadáMineralogical Assoc Canada2013-12info:eu-repo/semantics/articleinfo:eu-repo/semantics/publishedVersionhttp://purl.org/coar/resource_type/c_6501info:ar-repo/semantics/articuloapplication/pdfapplication/pdfhttp://hdl.handle.net/11336/9065Maydagán, Laura; Franchini, Marta Beatriz; Lentz, Dave ; Pons, María Josefina; McFarlane, Christopher ; Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System; Mineralogical Assoc Canada; Canadian Mineralogist; 51; 6; 12-2013; 813-8400008-4476enginfo:eu-repo/semantics/altIdentifier/url/http://www.canmin.org/content/51/6/813.abstractinfo:eu-repo/semantics/altIdentifier/doi/10.3749/canmin.51.6.813info:eu-repo/semantics/openAccesshttps://creativecommons.org/licenses/by-nc-sa/2.5/ar/reponame:CONICET Digital (CONICET)instname:Consejo Nacional de Investigaciones Científicas y Técnicas2025-09-03T10:04:14Zoai:ri.conicet.gov.ar:11336/9065instacron:CONICETInstitucionalhttp://ri.conicet.gov.ar/Organismo científico-tecnológicoNo correspondehttp://ri.conicet.gov.ar/oai/requestdasensio@conicet.gov.ar; lcarlino@conicet.gov.arArgentinaNo correspondeNo correspondeNo correspondeopendoar:34982025-09-03 10:04:14.386CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicasfalse
dc.title.none.fl_str_mv Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
title Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
spellingShingle Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
Maydagán, Laura
Trace Elements
Sulfides
S Isotopes
Porphyry-Epithermal
title_short Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
title_full Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
title_fullStr Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
title_full_unstemmed Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
title_sort Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System
dc.creator.none.fl_str_mv Maydagán, Laura
Franchini, Marta Beatriz
Lentz, Dave
Pons, María Josefina
McFarlane, Christopher
author Maydagán, Laura
author_facet Maydagán, Laura
Franchini, Marta Beatriz
Lentz, Dave
Pons, María Josefina
McFarlane, Christopher
author_role author
author2 Franchini, Marta Beatriz
Lentz, Dave
Pons, María Josefina
McFarlane, Christopher
author2_role author
author
author
author
dc.subject.none.fl_str_mv Trace Elements
Sulfides
S Isotopes
Porphyry-Epithermal
topic Trace Elements
Sulfides
S Isotopes
Porphyry-Epithermal
purl_subject.fl_str_mv https://purl.org/becyt/ford/1.5
https://purl.org/becyt/ford/1
dc.description.none.fl_txt_mv Sulfides and sulfosalts from the porphyry, transitional, and epithermal high sulfidation stages of the Altar Cu-(Au) deposit (San Juan, Argentina) were investigated by electron microprobe, laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS), and S isotopic analysis. Compositional differences found in the trace-element content in pyrite, chalcopyrite, and enargite from different alteration zones and depths of the system have implications in the physicochemical evolution of the hydrothermal fluids and might have potential for exploration in similar porphyry-high sulfidation epithermal environments. Low contents of most analyzed trace elements were found in chalcopyrite ± pyrite from the potassic alteration, except for Zn, Sn, and Ag in chalcopyrite, and Co and Ni in pyrite. During the phyllic alteration, cooling of the fluids and a decrease of its pH (<4.5) produced the leaching and re-precipitation of the sulfides from the previous stage. The reprecipitated chalcopyrite and pyrite show micro-inclusions of Au (Ag alloys) and sulfosalts with As, Ag, V, Zn, Sn, Bi, and Sb that are interpreted to correlate with changes in the composition of the fluids. In the transitional veins and their selvages, early precipitation of bornite + pyrite and the weak kaolinite + quartz alteration envelope indicate a decrease in the temperature (<200 °C) and pH (<4) of the fluids and an increase of the fS2. This stage was followed by a sudden increase in the fO2 of the fluid and a slight decrease in the fS2, and bornite was replaced by tennantite (vein type E1). A trend toward higher fS2 favored enargite precipitation (vein type E3). Traces of Au found in tennantite and enargite therefore indicate that fluctuations in the oxidation state of the fluids promoted gold precipitation in the Altar porphyry system. Negative S isotope values (δ34S: –1.7 to –3.0‰) obtained for the sulfides and sulfosalts from the potassic, phyllic, and transitional stages at Altar are consistent with oxidizing (SO4 2– dominant) mineralizing fluids. The precipitation of sphalerite (δ34S = –4.4‰ and low concentration of FeS) and galena associated with calcite + anhydrite in late fractures (vein type 8) reflect cooling of the fluids and a slight increase of its pH at higher fO2, as the system moved to greater depths. The typical advanced argillic assemblages are not developed at the Altar porphyry deposit, indicating that fluids did not attain very low pH conditions. In contrast, enargite from the epithermal siliceous ledges located above the porphyry deposit precipitated with low pH mineral assemblages (quartz + alunite) and has a distinctive lighter δ34S value of –5.4‰, consistent with a decrease of temperature, pH, and/or an increase in the oxidation state of the fluids during its deposition. Enargite from the transitional stage veins of the porphyry deposit is enriched in Zn, Sb, Ag, and Bi, whereas enargite from the epithermal environment has much lower concentrations of trace elements, except for isolated inclusions of Au-Bi.
Fil: Maydagán, Laura. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; Argentina
Fil: Franchini, Marta Beatriz. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; Argentina
Fil: Lentz, Dave . University of New Brunswick. Department of Earth Sciences; Canadá
Fil: Pons, María Josefina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentina. Universidad Nacional del Comahue. Facultad de Ingenieria. Departamento de Geologia y Petroleo; Argentina
Fil: McFarlane, Christopher . University of New Brunswick. Department of Earth Sciences; Canadá
description Sulfides and sulfosalts from the porphyry, transitional, and epithermal high sulfidation stages of the Altar Cu-(Au) deposit (San Juan, Argentina) were investigated by electron microprobe, laser ablation-inductively coupled plasma-mass spectroscopy (LA-ICP-MS), and S isotopic analysis. Compositional differences found in the trace-element content in pyrite, chalcopyrite, and enargite from different alteration zones and depths of the system have implications in the physicochemical evolution of the hydrothermal fluids and might have potential for exploration in similar porphyry-high sulfidation epithermal environments. Low contents of most analyzed trace elements were found in chalcopyrite ± pyrite from the potassic alteration, except for Zn, Sn, and Ag in chalcopyrite, and Co and Ni in pyrite. During the phyllic alteration, cooling of the fluids and a decrease of its pH (<4.5) produced the leaching and re-precipitation of the sulfides from the previous stage. The reprecipitated chalcopyrite and pyrite show micro-inclusions of Au (Ag alloys) and sulfosalts with As, Ag, V, Zn, Sn, Bi, and Sb that are interpreted to correlate with changes in the composition of the fluids. In the transitional veins and their selvages, early precipitation of bornite + pyrite and the weak kaolinite + quartz alteration envelope indicate a decrease in the temperature (<200 °C) and pH (<4) of the fluids and an increase of the fS2. This stage was followed by a sudden increase in the fO2 of the fluid and a slight decrease in the fS2, and bornite was replaced by tennantite (vein type E1). A trend toward higher fS2 favored enargite precipitation (vein type E3). Traces of Au found in tennantite and enargite therefore indicate that fluctuations in the oxidation state of the fluids promoted gold precipitation in the Altar porphyry system. Negative S isotope values (δ34S: –1.7 to –3.0‰) obtained for the sulfides and sulfosalts from the potassic, phyllic, and transitional stages at Altar are consistent with oxidizing (SO4 2– dominant) mineralizing fluids. The precipitation of sphalerite (δ34S = –4.4‰ and low concentration of FeS) and galena associated with calcite + anhydrite in late fractures (vein type 8) reflect cooling of the fluids and a slight increase of its pH at higher fO2, as the system moved to greater depths. The typical advanced argillic assemblages are not developed at the Altar porphyry deposit, indicating that fluids did not attain very low pH conditions. In contrast, enargite from the epithermal siliceous ledges located above the porphyry deposit precipitated with low pH mineral assemblages (quartz + alunite) and has a distinctive lighter δ34S value of –5.4‰, consistent with a decrease of temperature, pH, and/or an increase in the oxidation state of the fluids during its deposition. Enargite from the transitional stage veins of the porphyry deposit is enriched in Zn, Sb, Ag, and Bi, whereas enargite from the epithermal environment has much lower concentrations of trace elements, except for isolated inclusions of Au-Bi.
publishDate 2013
dc.date.none.fl_str_mv 2013-12
dc.type.none.fl_str_mv info:eu-repo/semantics/article
info:eu-repo/semantics/publishedVersion
http://purl.org/coar/resource_type/c_6501
info:ar-repo/semantics/articulo
format article
status_str publishedVersion
dc.identifier.none.fl_str_mv http://hdl.handle.net/11336/9065
Maydagán, Laura; Franchini, Marta Beatriz; Lentz, Dave ; Pons, María Josefina; McFarlane, Christopher ; Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System; Mineralogical Assoc Canada; Canadian Mineralogist; 51; 6; 12-2013; 813-840
0008-4476
url http://hdl.handle.net/11336/9065
identifier_str_mv Maydagán, Laura; Franchini, Marta Beatriz; Lentz, Dave ; Pons, María Josefina; McFarlane, Christopher ; Sulfide Composition and Isotopic Signature of the Altar Cu-Au Deposit, Argentina: constraints on the Evolution of the Porphyry-Epithermal System; Mineralogical Assoc Canada; Canadian Mineralogist; 51; 6; 12-2013; 813-840
0008-4476
dc.language.none.fl_str_mv eng
language eng
dc.relation.none.fl_str_mv info:eu-repo/semantics/altIdentifier/url/http://www.canmin.org/content/51/6/813.abstract
info:eu-repo/semantics/altIdentifier/doi/10.3749/canmin.51.6.813
dc.rights.none.fl_str_mv info:eu-repo/semantics/openAccess
https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
eu_rights_str_mv openAccess
rights_invalid_str_mv https://creativecommons.org/licenses/by-nc-sa/2.5/ar/
dc.format.none.fl_str_mv application/pdf
application/pdf
dc.publisher.none.fl_str_mv Mineralogical Assoc Canada
publisher.none.fl_str_mv Mineralogical Assoc Canada
dc.source.none.fl_str_mv reponame:CONICET Digital (CONICET)
instname:Consejo Nacional de Investigaciones Científicas y Técnicas
reponame_str CONICET Digital (CONICET)
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instname_str Consejo Nacional de Investigaciones Científicas y Técnicas
repository.name.fl_str_mv CONICET Digital (CONICET) - Consejo Nacional de Investigaciones Científicas y Técnicas
repository.mail.fl_str_mv dasensio@conicet.gov.ar; lcarlino@conicet.gov.ar
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