The relation between Cu/Au ratio and formation depth of porphyry-style Cu–Au ± Mo deposits

Murakami, Hiroyasu; Seo, Jung Hun; Heinrich, Christoph A.

doi:10.1007/s00126-009-0255-1

Cited by 87 publications

(34 citation statements)

References 76 publications

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“…3A), can yield oscillatory patterns in Au solubility in the T-P space (depending on the Fe/S ratio in the degassing magmatic fluid and the degree of fluid interaction with alkali aluminosilicate rocks). Such patterns contribute, along with other possible factors evoked so far, such as magma-fluid and vapor-brine separation (3,16,30), to the large spatial variations of Au grades and Au/Cu ratios reported between porphyry deposits. Furthermore, the S − 3 may also control incorporation of Au in a chemically bound state into pyrite, which is the major Au host of many epithermal and Carlin-type deposits (8,38).…”

Section: Discussion and Geological And Metallogenic Applicationsmentioning

confidence: 67%

Sulfur radical species form gold deposits on Earth

Pokrovski

Kokh

Guillaume

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

119

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Current models of the formation and distribution of gold deposits on Earth are based on the long-standing paradigm that hydrogen sulfide and chloride are the ligands responsible for gold mobilization and precipitation by fluids across the lithosphere. Here we challenge this view by demonstrating, using in situ X-ray absorption spectroscopy and solubility measurements, coupled with molecular dynamics and thermodynamic simulations, that sulfur radical species, such as the trisulfur ion S − 3 , form very stable and soluble complexes with Au + in aqueous solution at elevated temperatures (>250°C) and pressures (>100 bar). These species enable extraction, transport, and focused precipitation of gold by sulfur-rich fluids 10-100 times more efficiently than sulfide and chloride only. As a result, S − 3 exerts an important control on the source, concentration, and distribution of gold in its major economic deposits from magmatic, hydrothermal, and metamorphic settings. The growth and decay of S − 3 during the fluid generation and evolution is one of the key factors that determine the fate of gold in the lithosphere.gold | sulfur | ore deposit | hydrothermal fluid | trisulfur ion

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Section: Discussion and Geological And Metallogenic Applicationsmentioning

confidence: 67%

Sulfur radical species form gold deposits on Earth

Pokrovski

Kokh

Guillaume

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

119

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show abstract

“…It is apparent on Fig. 11, that the expected Cu/Au ratios in the exsolving volatile phase are significantly lower in relatively reducing systems (fO 2 < NNO+1) than those found in porphyry type ore deposits (Murakami et al, 2010), while at higher fO 2 , the predicted Cu/Au ratios fall in the typical range of ore deposits. Consequently, the volatile input from underlying mafic magmas into the magmatichydrothermal environment will be indicated by low Cu/ Au ratios in the forming ore deposits.…”

Section: Geological Implicationsmentioning

confidence: 86%

Gold and copper in volatile saturated mafic to intermediate magmas: Solubilities, partitioning, and implications for ore deposit formation

Zajacz

Candela

Piccoli

et al. 2012

Geochimica et Cosmochimica Acta

115

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“…For example, despite large variations 819 of Cu/Au ratios in porphyry-style Cu-Au-Mo deposits (from 10 3 to 10 6 ), they roughly increase with depth 820 (Murakami et al, 2010). This was qualitatively interpreted by the more efficient precipitation of 821 chalcopyrite than gold from an ascending cooling magmatic fluid carrying Cu in the form of chloride 822 complexes, whereas Au remained in the fluid as soluble sulfide species (Murakami et al, 2010).…”

mentioning

confidence: 99%