Phase relations and the electrochemical determination of sulfur fugacity for selected reactions in the Cu–Fe–S and Fe–S systems at 1 bar and temperatures between 185 and 460 °C

Lusk, J.; Bray, D Maxwell

doi:10.1016/s0009-2541(02)00194-8

Cited by 48 publications

(24 citation statements)

References 33 publications

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“…Their coupled Ni and Cu-enrichment (Fig. 6d) shows that Group-I dunites crystallised Ni\Cu-rich BMS assemblages (Table 2 and (Lusk and Bray, 2002). Mss such as in the harzburgite GM453 subsequently decomposed into two mss and a pentlandite at Tb 300°C (Misra and Fleet, 1973).…”

Section: Cu\ni Rich Sulfide Melt Immiscibility In Group-i Xenolithsmentioning

confidence: 99%

In-situ geochemistry of sulfides in highly metasomatized mantle xenoliths from Kerguelen, southern Indian Ocean

Delpech

Lorand

Grégoire

et al. 2012

Lithos

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Section: Cu\ni Rich Sulfide Melt Immiscibility In Group-i Xenolithsmentioning

confidence: 99%

In-situ geochemistry of sulfides in highly metasomatized mantle xenoliths from Kerguelen, southern Indian Ocean

Delpech

Lorand

Grégoire

et al. 2012

Lithos

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“…The operation principle of the gas sensor (Sato, 1971;Schneeberg, 1973;Lusk and Bray, 2002) is based on the measurement of the potential of silver on the silver sulfide electrode with respect to pure silver. However, the electrochemical gas sensor always yields higher log a S2(g) values for the pyrrhotite-pyrite equilibrium, especially at low temperatures, reflecting the lower potential of silver, and therefore high potential of sulfur, on the sulfide electrode.…”

Section: Precision Of a S2 Determinationmentioning

confidence: 99%

“…The vertical position of the solvus (composition independent of temperature) or the inclined position (composition dependent on temperature) imply the possibility of using the system as a geo-barometer or geo-thermometer, respectively. Schneeberg (1973) used an electrochemical cell (potentiometric sensor of second kind) with separate gas space to determine the activity of gaseous sulfur (a S2 ) above the po + py buffer, but only four experimental points were obtained in the temperature range 597-711 K. Lusk and Bray (2002) used a modified Scheneeberg's cell and their own calibrations to measure a S2 above the po + py equilibrium in the temperature range 518-721 K.…”

Section: Introductionmentioning

confidence: 99%

Thermodynamic studies of pyrrhotite–pyrite equilibria in the Ag–Fe–S system by solid-state galvanic cell technique at 518–723K and total pressure of 1atm

Осадчий¹,

Чареев²

2006

Geochimica et Cosmochimica Acta

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“…Coexisting bornite + chalcopyrite + pyrite (Fig. 4A) suggest that some reequilibration took place at <237°C (Lusk and Bray, 2002), although this assemblage is uncommon. Exsolution textures in large, thermally insulated xenoliths may have been retained from prediatreme reequilibration.…”

Section: Diatreme Emplacement At Santa Cruzmentioning

confidence: 99%

Concealed Basalt-Matrix Diatremes with Cu-Au-Ag-(Mo)-Mineralized Xenoliths, Santa Cruz Porphyry Cu-(Mo) System, Pinal County, Arizona

Vikre

Graybeal²,

Koutz

2014

Economic Geology

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The Santa Cruz porphyry Cu-(Mo) system near Casa Grande, Arizona, includes the Sacaton mine deposits and at least five other concealed, mineralized fault blocks with an estimated minimum resource of 1.5 Gt @ 0.6% Cu. The Late Cretaceous-Paleocene system has been dismembered and rotated by Tertiary extension, partially eroded, and covered by Tertiary-Quaternary basin-fill deposits. The mine and mineralized fault blocks, which form an 11 km (~7 miles) by 1.6 km (~1 mile) NE-SW-trending alignment, represent either pieces of one large deposit, several deposits, or pieces of several deposits. The southwestern part of the known system is penetrated by three or more diatremes that consist of heterolithic breccia pipes with basalt and clastic matrices, and subannular tuff ring and maar-fill sedimentary deposits associated with vents. The tephra and maar-fill deposits, which are covered by ~485 to 910 m (~1,600-3,000 ft) of basin fill, lie on a mid-Tertiary erosion surface of Middle Proterozoic granite and Late Cretaceous porphyry, which compose most xenoliths in pipes and are the host rocks of the system. Some igneous xenoliths in the pipes contain bornite-chalcopyrite-covellite assemblages with hypogene grades >1 wt % Cu, 0.01 ounces per ton (oz/t) Au, 0.5 oz/t Ag, and small amounts of Mo (<0.01 wt %). These xenoliths were derived from mineralized rocks that have not been encountered in drill holes, and attest to additional, possibly higher-grade deposits within or subjacent to the known system.The geometry, stratigraphy, and temporal relationships of pipes and tephras, interpreted from drill hole spacing and intercepts, multigenerational breccias and matrices, reequilibrated and partially decomposed sulfideoxide mineral assemblages, melted xenoliths, and breccia matrix compositions show that the diatremes formed in repeated stages. Initial pulses of basalt magma fractured granite, porphyry, and other crustal rocks during intrusion, transported multi-sized fragments of these rocks upward, and partially melted small fragments. Rapid decompression of magma induced catastrophic devolatilization that ruptured overlying rocks to the surface, and generated fragment-volatile suspensions that abraded conduits into near-vertical cylindrical structures. Fragments entrained in suspensions were milled and sorted, and ejected as basal surge, pyroclastic deposits, and airfall tephra that built tuff rings around vents and filled vent depressions. Comminuted m-to mm-sized fragments of wall rocks in magma and suspensions that remained in conduits solidified as heterolithic breccias. Subsequent pulses of basalt magma ascended through the same conduits, brecciated older heterolithic breccias, devolatilized, and quenched, leaving two or more generations of nested and mingled heterolithic breccias and internal zones of fluidized fragments. Tephra and maar-fill deposits from later eruptions are composed of more hydrous and oxidized minerals than earlier tephras, reflecting a higher proportion of water in transport fluid which, based on fluid...

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Phase relations and the electrochemical determination of sulfur fugacity for selected reactions in the Cu–Fe–S and Fe–S systems at 1 bar and temperatures between 185 and 460 °C

Cited by 48 publications

References 33 publications

In-situ geochemistry of sulfides in highly metasomatized mantle xenoliths from Kerguelen, southern Indian Ocean

In-situ geochemistry of sulfides in highly metasomatized mantle xenoliths from Kerguelen, southern Indian Ocean

Thermodynamic studies of pyrrhotite–pyrite equilibria in the Ag–Fe–S system by solid-state galvanic cell technique at 518–723K and total pressure of 1atm

Concealed Basalt-Matrix Diatremes with Cu-Au-Ag-(Mo)-Mineralized Xenoliths, Santa Cruz Porphyry Cu-(Mo) System, Pinal County, Arizona

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