Sulfur isotopes, trace element, and textural analyses of pyrite, arsenopyrite and base metal sulfides associated with gold mineralization in the Pataz-Parcoy district, Peru: implication for paragenesis, fluid source, and gold deposition mechanisms

F. Voute, S. G. Hagemann, N. J. Evans, C. Villanes

Research output: Contribution to journalArticle

1 Citation (Scopus)

Abstract

In the Pataz-Parcoy district, current mining activity is focused on the mesothermal quartz-carbonate-sulfide veins hosted by the Pataz batholith. Total gold production yielded approximately 8 Moz with grades in the mined ore shoots varying between 7 and 15 g/t Au, and locally reaching up to 120 g/t Au. High-grade ore shoots are extraordinarily enriched in sulfides, representing 10 to 20 modal vol% of the vein. Ore mineralogy is characterized by a complex paragenesis of pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, and gold. Gold occurs mostly as electrum in equilibrium with base metals sulfides filling fractures of pyrite and arsenopyrite. A novel combination of secondary ion mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron probe microanalysis is used to track the compositional evolution of ore fluid(s) and to investigate the mineralization processes occurring in the Pataz-Parcoy district. Contrasting with the classical two-stage ore sequence previously proposed for the Pataz-Parcoy district, we suggest a revised paragenetic sequence, i.e., (1) deposition of pyrite core (PyI) with homogeneously distributed base metal sulfide inclusions, (2) progressive replacement of PyI by arsenian pyrite (PyII) and arsenopyrite associated with invisible gold deposition, and (3) deposition of sphalerite – galena ± chalcopyrite − electrum in fractured pyrite and arsenopyrite. We propose two models for the formation of base metal sulfide inclusions in PyI, i.e., (1) co-precipitation of base metal sulfide with PyI and later redistribution in cracks driven by partial As replacement of PyI to PyII and arsenopyrite and (2) preferential replacement of the PyI along crystallographic planes by percolation of the fluid responsible for base metal sulfide deposition in fractured pyrite and arsenopyrite.

Original languageEnglish
JournalMineralium Deposita
DOIs
Publication statusE-pub ahead of print - 3 Jan 2019

Fingerprint

Sulfur Isotopes
sulfur isotopes
Peru
arsenopyrite
sulfur isotope
Trace Elements
Sulfides
pyrites
paragenesis
base metal
trace elements
Gold
sulfides
pyrite
gold
Metals
sulfide
trace element
mineralization
Fluids

Cite this

@article{4fdc72bbcb864f9b8659704edf6d272b,
title = "Sulfur isotopes, trace element, and textural analyses of pyrite, arsenopyrite and base metal sulfides associated with gold mineralization in the Pataz-Parcoy district, Peru: implication for paragenesis, fluid source, and gold deposition mechanisms",
abstract = "In the Pataz-Parcoy district, current mining activity is focused on the mesothermal quartz-carbonate-sulfide veins hosted by the Pataz batholith. Total gold production yielded approximately 8 Moz with grades in the mined ore shoots varying between 7 and 15 g/t Au, and locally reaching up to 120 g/t Au. High-grade ore shoots are extraordinarily enriched in sulfides, representing 10 to 20 modal vol{\%} of the vein. Ore mineralogy is characterized by a complex paragenesis of pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, and gold. Gold occurs mostly as electrum in equilibrium with base metals sulfides filling fractures of pyrite and arsenopyrite. A novel combination of secondary ion mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron probe microanalysis is used to track the compositional evolution of ore fluid(s) and to investigate the mineralization processes occurring in the Pataz-Parcoy district. Contrasting with the classical two-stage ore sequence previously proposed for the Pataz-Parcoy district, we suggest a revised paragenetic sequence, i.e., (1) deposition of pyrite core (PyI) with homogeneously distributed base metal sulfide inclusions, (2) progressive replacement of PyI by arsenian pyrite (PyII) and arsenopyrite associated with invisible gold deposition, and (3) deposition of sphalerite – galena ± chalcopyrite − electrum in fractured pyrite and arsenopyrite. We propose two models for the formation of base metal sulfide inclusions in PyI, i.e., (1) co-precipitation of base metal sulfide with PyI and later redistribution in cracks driven by partial As replacement of PyI to PyII and arsenopyrite and (2) preferential replacement of the PyI along crystallographic planes by percolation of the fluid responsible for base metal sulfide deposition in fractured pyrite and arsenopyrite.",
keywords = "Arsenian pyrite, Arsenopyrite, Invisible gold, Paragenetic sequence, Sulfur isotopes, Trace element",
author = "F. Voute and Hagemann, {S. G.} and Evans, {N. J.} and C. Villanes",
year = "2019",
month = "1",
day = "3",
doi = "10.1007/s00126-018-0857-6",
language = "English",
journal = "Mineralium Deposita: international journal of geology, mineralogy, and geochemistry of mineral deposits",
issn = "0026-4598",
publisher = "Springer-Verlag London Ltd.",

}

TY - JOUR

T1 - Sulfur isotopes, trace element, and textural analyses of pyrite, arsenopyrite and base metal sulfides associated with gold mineralization in the Pataz-Parcoy district, Peru

T2 - implication for paragenesis, fluid source, and gold deposition mechanisms

AU - Voute, F.

AU - Hagemann, S. G.

AU - Evans, N. J.

AU - Villanes, C.

PY - 2019/1/3

Y1 - 2019/1/3

N2 - In the Pataz-Parcoy district, current mining activity is focused on the mesothermal quartz-carbonate-sulfide veins hosted by the Pataz batholith. Total gold production yielded approximately 8 Moz with grades in the mined ore shoots varying between 7 and 15 g/t Au, and locally reaching up to 120 g/t Au. High-grade ore shoots are extraordinarily enriched in sulfides, representing 10 to 20 modal vol% of the vein. Ore mineralogy is characterized by a complex paragenesis of pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, and gold. Gold occurs mostly as electrum in equilibrium with base metals sulfides filling fractures of pyrite and arsenopyrite. A novel combination of secondary ion mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron probe microanalysis is used to track the compositional evolution of ore fluid(s) and to investigate the mineralization processes occurring in the Pataz-Parcoy district. Contrasting with the classical two-stage ore sequence previously proposed for the Pataz-Parcoy district, we suggest a revised paragenetic sequence, i.e., (1) deposition of pyrite core (PyI) with homogeneously distributed base metal sulfide inclusions, (2) progressive replacement of PyI by arsenian pyrite (PyII) and arsenopyrite associated with invisible gold deposition, and (3) deposition of sphalerite – galena ± chalcopyrite − electrum in fractured pyrite and arsenopyrite. We propose two models for the formation of base metal sulfide inclusions in PyI, i.e., (1) co-precipitation of base metal sulfide with PyI and later redistribution in cracks driven by partial As replacement of PyI to PyII and arsenopyrite and (2) preferential replacement of the PyI along crystallographic planes by percolation of the fluid responsible for base metal sulfide deposition in fractured pyrite and arsenopyrite.

AB - In the Pataz-Parcoy district, current mining activity is focused on the mesothermal quartz-carbonate-sulfide veins hosted by the Pataz batholith. Total gold production yielded approximately 8 Moz with grades in the mined ore shoots varying between 7 and 15 g/t Au, and locally reaching up to 120 g/t Au. High-grade ore shoots are extraordinarily enriched in sulfides, representing 10 to 20 modal vol% of the vein. Ore mineralogy is characterized by a complex paragenesis of pyrite, arsenopyrite, galena, sphalerite, chalcopyrite, and gold. Gold occurs mostly as electrum in equilibrium with base metals sulfides filling fractures of pyrite and arsenopyrite. A novel combination of secondary ion mass spectrometry, laser ablation inductively coupled plasma mass spectrometry, and electron probe microanalysis is used to track the compositional evolution of ore fluid(s) and to investigate the mineralization processes occurring in the Pataz-Parcoy district. Contrasting with the classical two-stage ore sequence previously proposed for the Pataz-Parcoy district, we suggest a revised paragenetic sequence, i.e., (1) deposition of pyrite core (PyI) with homogeneously distributed base metal sulfide inclusions, (2) progressive replacement of PyI by arsenian pyrite (PyII) and arsenopyrite associated with invisible gold deposition, and (3) deposition of sphalerite – galena ± chalcopyrite − electrum in fractured pyrite and arsenopyrite. We propose two models for the formation of base metal sulfide inclusions in PyI, i.e., (1) co-precipitation of base metal sulfide with PyI and later redistribution in cracks driven by partial As replacement of PyI to PyII and arsenopyrite and (2) preferential replacement of the PyI along crystallographic planes by percolation of the fluid responsible for base metal sulfide deposition in fractured pyrite and arsenopyrite.

KW - Arsenian pyrite

KW - Arsenopyrite

KW - Invisible gold

KW - Paragenetic sequence

KW - Sulfur isotopes

KW - Trace element

UR - http://www.scopus.com/inward/record.url?scp=85059511146&partnerID=8YFLogxK

U2 - 10.1007/s00126-018-0857-6

DO - 10.1007/s00126-018-0857-6

M3 - Article

JO - Mineralium Deposita: international journal of geology, mineralogy, and geochemistry of mineral deposits

JF - Mineralium Deposita: international journal of geology, mineralogy, and geochemistry of mineral deposits

SN - 0026-4598

ER -