Multiple fluid generations in the Sudbury igneous complex: fluid inclusion, Ar, O, H, Rb and Sr evidence

Marshall, Daniel D.; Watkinson, David H.; Farrow, Catharine E. G.; Molnár, Ferenc; Fouillac, Anne‐Marie

doi:10.1016/s0009-2541(98)00122-3

Cited by 44 publications

(25 citation statements)

References 21 publications

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“…For comparison, Fe, Mn, Pb and Ba are present only in trace (<10 ppm) concentrations in the deep groundwaters of the Sudbury area (Frape and Fritz 1982) and the ore metals detected in the P brine inclusions could clearly not have been derived from the groundwaters. Therefore, models describing the interaction of heated groundwater with sulfide, or mixing of groundwater with a second fluid of magmatic origin exsolved from the SIC or from a sulfide liquid are supported by our new observations (Li 1993;Farrow 1994;Marshall et al 1999;Hanley et al 2004). …”

Section: Origin Of the Brine-ch 4 Assemblagesupporting

confidence: 72%

Ore metal redistribution by hydrocarbon–brine and hydrocarbon–halide melt phases, North Range footwall of the Sudbury Igneous Complex, Ontario, Canada

et al. 2005

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Ore metal redistribution by hydrocarbon-brine and hydrocarbon-halide melt phases, North Range footwall of the Sudbury Igneous Complex, Ontario, Canada Abstract We report methane-dominant hydrocarbon (fluid) inclusions (CH 4 ±C 2 H 6 -C 2 H 2 , C 3 H 8 ) coexisting with primary brine inclusions and secondary halidemelt (solid NaCl) inclusions in Au-Pt-rich quartz-sulfide-epidote alteration veins associated with the footwall-style Cu-PGE (platinum-group element)-Au deposits at the Fraser Mine (North Range of the Sudbury Igneous Complex). Evidence for coentrapment of immiscible hydrocarbon-brine, and hydrocarbonhalide melt mixtures is demonstrated. A primary CH 4 -brine assemblage was trapped during quartz growth at relatively low T (min. T trapping $145-315°C) and P (max. P trapping $500 bar), prior to the crystallization of sulfide minerals in the veins. Secondary inclusions contain solid halite and a mixture of CH 4 , C 2 H 6 -C 2 H 2 and C 3 H 8 and were trapped at a minimum T of $710°C. The halite inclusions may represent halidemelt that exsolved from crystallizing sulfide ores that texturally postdate (by replacement) early alteration quartz hosting the primary, lower T brine-CH 4 assemblage. Laser ablation ICP-MS analyses show that the brine, hydrocarbon and halide-melt inclusions contain significant concentrations of Cu (0.1-1 wt% range), Au, Bi, Ag and Pt (all 0.1-10 ppm range). Cu:Pt and Cu:Au ratios in the inclusions are significantly (up to 4 log units) lower than in the host alteration veins and adjacent massive sulfide ore veins, suggesting either (1) are lower for Cu, Au, Bi and Ag than for other elements (Na, Ca, Fe, Mn, Zn, Pb) indicating that during interaction with the brine, the hydrocarbon phase was enriched in ore metals. The high concentrations of ore metals in hydrocarbon, brine and halide-melt phases confirm that both aqueous and non-aqueous volatiles were carriers of precious metals in the Sudbury environment over a wide range of temperatures. Volatile evolution and magmatic sulfide differentiation were clearly part of a single, continuous process in the Sudbury footwall. The exsolution of H 2 O-poor volatiles from fractionated sulfide liquid may have been a principal mechanism controlling the final distribution of PGE and Au in the footwall ore systems. The study reports the first measurements of precious metal concentrations in fluid inclusions from a magmatic Ni-Cu-PGE environment (the Sudbury district).

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Section: Origin Of the Brine-ch 4 Assemblagesupporting

confidence: 72%

Ore metal redistribution by hydrocarbon–brine and hydrocarbon–halide melt phases, North Range footwall of the Sudbury Igneous Complex, Ontario, Canada

et al. 2005

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“…Minor hydrothermal fluid flow beneath the Complex was also initiated by heating footwall ground waters with recharge from deep formational brines (Fig. 3;Farrow, 1994;Farrow and Watkinson, 1999;Marshall et al, 1999;Watkinson, 1999) as has been recorded in other impact structures (e.g., Komor et al, 1988;Pevzner et al, 1992;Masaytis and Naumov, 1995). The hydrothermal circulation system altered the crater-fill deposits around the entire circumference of the exposed structure (>6,000 km 3 ), mainly altering the vitric fragments in the fragmental rocks (Ames, 1999;Ames et al, 2000).…”

Section: Sudbury Structure Hydrothermal Systemmentioning

confidence: 80%

Vitric Compositions in the Onaping Formation and Their Relationship to the Sudbury Igneous Complex, Sudbury Structure

Ames¹,

Golightly²,

Lightfoot³

et al. 2002

Economic Geology

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“…Olivine melagabbronorites, the host rocks in the Tootoo and Mequillon magmatic sulfide deposits, were pervasively altered to hydrous mineral assemblages dominated by chlorite, tremolite-actinolite, and relict late-magmatic hornblende that are consistent with greenschist facies metamorphism [22]. Large-scale and very saline hydrothermal fluid activity is also interpreted to have affected rocks of the Sudbury Complex and in the process caused remobilization of both base metals and PGEs [105,106].…”

Section: Discussionmentioning

confidence: 96%

Hydrothermal Alteration in the Main Sulfide Zone at Unki Mine, Shurugwi Subchamber of the Great Dyke, Zimbabwe: Evidence from Petrography and Silicates Mineral Chemistry

Chaumba

2017

Minerals

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Abstract:The main platinum-group element (PGE) occurrence in the Great Dyke of Zimbabwe, the Main Sulfide Zone (MSZ), is a tabular stratabound layer hosted in pyroxenites. A petrographic and silicate composition study across the MSZ at Unki Mine in the Shurugwi Subchamber was conducted to help place some constrains on the origin of the mineralization. The PGE-enriched zone at Unki Mine is a~10 m thick package of rocks ranging from gabbronorites, a chromitite stringer, plagioclase websterite, plagioclase pyroxenite (pegmatitic in one narrow zone), a base metal sulfide zone and it is largely located below the contact of the Mafic and Ultramafic Sequences. Pyroxenes have been partially hydrothermally altered to amphibole and chlorite in most lithologies. In addition, sulfides tend to occur as cumulus phases or as inclusions in all the silicate phases. Two generations of sulfide mineralization likely occurred at Unki Mine with primary sulfides occurring in association with cumulus phases, and the relatively finer-grained, often lath-like, sulfides that occur in association with alteration phases of chlorite and amphibole that were likely formed later during hydrothermal alteration. Chlorite thermometry yields temperatures ranging from 241 to 390 • C, and from 491 to 640 • C, and they are interpreted to be temperatures recording the hydrothermal event(s) of magmatic origin which affected the mineralization at Unki Mine. Two-pyroxene thermometry yields temperatures that range from 850 to 981 • C, and these temperatures are interpreted to indicate a hydrothermal imprint on the minerals that constitute the MSZ.

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Multiple fluid generations in the Sudbury igneous complex: fluid inclusion, Ar, O, H, Rb and Sr evidence

Cited by 44 publications

References 21 publications

Ore metal redistribution by hydrocarbon–brine and hydrocarbon–halide melt phases, North Range footwall of the Sudbury Igneous Complex, Ontario, Canada

Ore metal redistribution by hydrocarbon–brine and hydrocarbon–halide melt phases, North Range footwall of the Sudbury Igneous Complex, Ontario, Canada

Vitric Compositions in the Onaping Formation and Their Relationship to the Sudbury Igneous Complex, Sudbury Structure

Hydrothermal Alteration in the Main Sulfide Zone at Unki Mine, Shurugwi Subchamber of the Great Dyke, Zimbabwe: Evidence from Petrography and Silicates Mineral Chemistry

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