Deposition of a high-sulfidation Au assemblage from a magmatic volatile phase, Volcán Popocatépetl, Mexico

Larocque, Adrienne C. L.; Stimac, James A.; Siebe, Claus; Greengrass, Karen; Chapman, Ron; Mejia, Sergio R.

doi:10.1016/j.jvolgeores.2007.09.009

Cited by 38 publications

(18 citation statements)

References 28 publications

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“…The telluride and sulfosalt mineralogy, the low Fe content of sphalerite and the fluid-inclusion data indicate that the mineralizing fluids were of intermediate-to high-sulfidation states (Hedenquist et al 2000, Voudouris & Melfos 2006, and that Te and Bi were derived from spatially associated porphyries (Afifi et al 1988, Jensen & Barton 2000, Borodaev et al 2000, Cooke & McPhail 2001. The presence of tellurides and a Sn-bearing lead oxide in the ore system at the Pagoni Rachi prospect is also compatible with direct deposition from the vapor phase, as indicated by the presence by calaverite, stannite, and an unknown Au-Cu telluride in vesicles in Volcan Popocatépetl, Mexico (Larocque et al 2008). Jensen & Barton (2000) contended that Te-enrichment in melts was derived by previous subduction of Te-rich sediments.…”

Section: From Re Deposition To Te Enrichmentmentioning

confidence: 79%

RHENIUM-RICH MOLYBDENITE AND RHENIITE IN THE PAGONI RACHI Mo-Cu-Te-Ag-Au PROSPECT, NORTHERN GREECE: IMPLICATIONS FOR THE Re GEOCHEMISTRY OF PORPHYRY-STYLE Cu-Mo AND Mo MINERALIZATION

Voudouris¹,

Melfos²,

Spry³

et al. 2009

The Canadian Mineralogist

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The porphyry-type Pagoni Rachi Mo-Cu-Te-Ag-Au prospect, in northern Greece, is a porphyry-epithermal system hosted by an Oligocene dacite porphyry and quartz-feldspar porphyry dikes. The rare mineral rheniite (ReS 2 ) and molybdenite, with very high contents of Re (up to 4.7 wt% Re), occur in quartz veins along with Fe-Cu sulfides, Pb-, Sn-, and Cl-bearing oxides, hematite, ilmenite and tellurides of Bi; these veins are spatially related to sericitic and transitional sericitic-sodic-potassic alteration. Earlier-formed gold-bearing quartz and magnetite veins with sodic-potassic-calcic alteration and late precious-metal telluride-rich carbonate-quartz veins with argillic alteration contain only minor amounts of molybdenite. The composition of rheniite ranges from almost pure, stoichiometric rheniite with low Mo content to rheniite with up to 5.99 wt% Mo. Petrographic, scanning electron microscope, and structural studies suggest that the high Re content of molybdenite from Pagoni Rachi is the result of the isovalent Re-for-Mo substitution in molybdenite. This fact is corroborated by the progressive shortening of the Mo-S mean bond-distance (from 2.414 Å in pure molybdenite to 2.355 Å), as well as by the isotropic decrease of the unit-cell values with the increase of the Re:Mo ratio. The structural analysis of four molybdenite crystals, with the highest Re content ever reported in nature, demonstrates that they crystallize as the 2H polytype and not the 3R polytype, as previously hypothesized, thus suggesting that Re concentration does not correlate with a specific polytype. The fluid inclusions in quartz in the Re-bearing molybdenite-rheniite veins at Pagoni Rachi show that they homogenize to either the liquid or vapor phases (354 to 428°C) or by halite dissolution at 317 to 585°C, which equates to salinities of 40 to 59 wt% NaCl equiv. Rheniite and molybdenite likely precipitated as temperatures fell below 400°C during phase separation under relatively oxidizing conditions, at elevated chlorine activity, and from relatively acid hydrothermal solutions. However, the presence of Pb oxides, Sn-bearing minerals and tellurides § E-mail address: voudouris@geol.uoa.gr 1014 thE CanaDian MinERalogist is compelling evidence that rheniite and Re-rich molybdenite may have formed directly from the vapor as sublimates, in a manner similar to the way they are deposited at the Kudriavy volcano, Kurile Islands.Keywords: porphyry-epithermal deposit, rheniite, Re-rich molybdenite, polytype, phase separation, tellurides, sublimates, Pagoni Rachi, Greece.soMMaiRE L'indice minéralisé en Mo-Cu-Te-Ag-Au de Pagoni Rachi, de type porphyre, situé dans le nord de la Grèce, est un système épithermal encaissé par un porphyre dacitique oligocène et des filons de porphyre quartzofeldspathique. Nous y avons trouvé la rhéniïte (ReS 2 ), espèce rare, et la molybdénite très enrichie en Re (jusqu'à 4.7% Re, poids), dans des veines de quartz avec des sulfures de Fe-Cu, des oxydes contenant Pb, Sn, et Cl, l'hématite, l'ilménite et des tellurure...

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Section: From Re Deposition To Te Enrichmentmentioning

confidence: 79%

RHENIUM-RICH MOLYBDENITE AND RHENIITE IN THE PAGONI RACHI Mo-Cu-Te-Ag-Au PROSPECT, NORTHERN GREECE: IMPLICATIONS FOR THE Re GEOCHEMISTRY OF PORPHYRY-STYLE Cu-Mo AND Mo MINERALIZATION

Voudouris¹,

Melfos²,

Spry³

et al. 2009

The Canadian Mineralogist

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“…During the main mineralization stage, the ore-metal bearing fluids subsequently precipitated gold, enargite, and pyrite by boiling, fluid mixing, or fluid de-sulfidation (Hedenquist et al, 1994;Williams-Jones and Heinrich, 2005). High-sulfidation mineral assemblages formed by crystallization directly from a magmatic volatile phase were suggested by Larocque et al (2008). According to Larocque et al (2008), a high proportion of the metal content of the original magma from Volcan Popocatepetl, Mexico was partitioned into a volatile phase which subsequently trapped and condensed as metal-bearing phases in the vesicles of pumice.…”

Section: Discussionmentioning

confidence: 99%

“…High-sulfidation mineral assemblages formed by crystallization directly from a magmatic volatile phase were suggested by Larocque et al (2008). According to Larocque et al (2008), a high proportion of the metal content of the original magma from Volcan Popocatepetl, Mexico was partitioned into a volatile phase which subsequently trapped and condensed as metal-bearing phases in the vesicles of pumice.…”

Section: Discussionmentioning

confidence: 99%

Physical and chemical characteristics of the host rocks in controlling the mineralization of the Chinkuashih high-sulfidation gold–copper deposits, northeastern Taiwan

Wang

2010

Journal of Geochemical Exploration

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“…The sulfide–sulfosalt assemblages preserved in the fracture system at El Indio around one thousand meters below the paleo‐surface provide insights to the processes occurring in modern active volcanoes. While enargite and tennantite are found in pumice on Popacatapetl, Mexico (Larocque et al. 2008), arsenic minerals are rare in fumarole sublimates except as complex sulfosalts such as vurroite, Pb 20 Sn 2 (Bi,As) 22 S 54 Cl 6 in association with other rare complex sulfosalts such as lillianite Pb 2.88 Bi 2.12 (S 5.67 Se 0.33 )S 6 and galenobismutite, Pb 3 Bi 2 S 6 (e.g., Garavelli et al.…”

Section: Synthesismentioning

confidence: 99%

Sulfosalt melts and heavy metal (As‐Sb‐Bi‐Sn‐Pb‐Tl) fractionation during volcanic gas expansion: the El Indio (Chile) paleo‐fumarole

Henley¹,

Mavrogenes²,

Tanner³

2011

Geofluids

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2012). Sulfosalt melts and heavy metal (As-Sb-Bi-Sn-Pb-Tl) fractionation during volcanic gas expansion: The El Indio (Chile) paleo-fumarole. Geofluids, 12 (3),[199][200][201][202][203][204][205][206][207][208][209][210][211][212][213][214][215] Sulfosalt melts and heavy metal (As-Sb-Bi-Sn-Pb-Tl) fractionation during volcanic gas expansion: The El Indio (Chile) paleo-fumarole AbstractHigh-sulfidation vein gold deposits such as El Indio, Chile, formed in fracture arrays <1000m beneath paleosolfatara in volcanic terranes. Stable isotope data have confirmed a predominance of magmatic vapor during the deposition of arsenic-rich sulfide-sulfosalt assemblages in this deposit. These provide a unique opportunity to analyze the processes and products of high-temperature volcanic gas expansion in fractures that form the otherwise inaccessible infrastructure deep inside equivalent present-day fumaroles. We provide field emission scanning electron microscope and LA-ICP-MS micro-analytical data for the wide range of>heavy, semi-metals and metalloids (arsenic, antimony, bismuth, tin, silver, gold, tellurium and selenium) in the complex pyrite-enargite-Fe-tennantite assemblages from Copper Stage mineralization in the El Indio deposit. These data document the progressive fractionation of antimony and other heavy metals, such as bismuth, during crystallization from a sulfosalt melt that condensed from expanding vapor at about 15MPa (150bars) and >650°C following higher temperature vapor deposition of crystalline pyrite and enargite. The sulfosalt melt aggressively corroded the earlier enargite and pyrite and hosts clusters of distinctive euhedral quartz crystals. The crystallizing sulfosalt melt also trapped an abundance of vugs within which heavy metal sulfide and sulfosalt crystals grew together with K-Al silicates and fluorapatite. These data and their geologic context suggest that, in high-temperature fumaroles on modern active volcanoes, over 90% of the arsenic content of the primary magmatic vapor (perhaps 2000mgkg -1) was precipitated subsurface as sulfosalt. ABSTRACTHigh-sulfidation vein gold deposits such as El Indio, Chile, formed in fracture arrays <1000 m beneath paleo-solfatara in volcanic terranes. Stable isotope data have confirmed a predominance of magmatic vapor during the deposition of arsenic-rich sulfide-sulfosalt assemblages in this deposit. These provide a unique opportunity to analyze the processes and products of high-temperature volcanic gas expansion in fractures that form the otherwise inaccessible infrastructure deep inside equivalent present-day fumaroles. We provide field emission scanning electron microscope and LA-ICP-MS micro-analytical data for the wide range of heavy, semi-metals and metalloids (arsenic, antimony, bismuth, tin, silver, gold, tellurium and selenium) in the complex pyrite-enargite-Fe-tennantite assemblages from Copper Stage mineralization in the El Indio deposit. These data document the progressive fractionation of antimony and other heavy metals, such as bismuth, during crystall...

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Deposition of a high-sulfidation Au assemblage from a magmatic volatile phase, Volcán Popocatépetl, Mexico

Cited by 38 publications

References 28 publications

RHENIUM-RICH MOLYBDENITE AND RHENIITE IN THE PAGONI RACHI Mo-Cu-Te-Ag-Au PROSPECT, NORTHERN GREECE: IMPLICATIONS FOR THE Re GEOCHEMISTRY OF PORPHYRY-STYLE Cu-Mo AND Mo MINERALIZATION

RHENIUM-RICH MOLYBDENITE AND RHENIITE IN THE PAGONI RACHI Mo-Cu-Te-Ag-Au PROSPECT, NORTHERN GREECE: IMPLICATIONS FOR THE Re GEOCHEMISTRY OF PORPHYRY-STYLE Cu-Mo AND Mo MINERALIZATION

Physical and chemical characteristics of the host rocks in controlling the mineralization of the Chinkuashih high-sulfidation gold–copper deposits, northeastern Taiwan

Sulfosalt melts and heavy metal (As‐Sb‐Bi‐Sn‐Pb‐Tl) fractionation during volcanic gas expansion: the El Indio (Chile) paleo‐fumarole

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