Micro-scale S isotope studies of the Kharaelakh intrusion, Noril’sk region, Siberia: Constraints on the genesis of coexisting anhydrite and sulfide minerals

Ripley, Edward M.; Li, Chusi; Moore, Craig H.; Schmitt, Axel K.

doi:10.1016/j.gca.2009.10.003

Cited by 41 publications

(11 citation statements)

References 33 publications

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“…Sulfur degassing could increase the δ 34 S of the magma, however it is unlikely to be the 5 mechanism generating exceptional δ 34 S values in ore-bearing intrusions, given that the majority of volcanic rocks in the area (certainly more degassed than intrusive rocks) have δ 34 S values lower than 5 ‰ . This corroborates the hypothesis of sulfate assimilation (Ripley et al 2010),…”

Section: Introductionsupporting

confidence: 91%

“…Combined assimilation of evaporitic and organic matter-bearing rocks has been already suggested by different authors (Naldrett 2004;Arndt et al 2005;Jugo and Lesher 2005;Li et al 2009b;Ripley et al 2010), but never exhaustively studied. Here we investigate the assimilation of both sulfate and organic compounds by means of experimental petrology and thermodynamic modeling: we show how they strongly control the redox state and the sulfur content of the magma and are therefore likely to play a fundamental role in the genesis of massive sulfide deposits.…”

Section: Introductionmentioning

confidence: 87%

“…together with the coexistence of magmatic anhydrite with sulfide minerals having anomalously high δ 34 S values in the Kharaelakh intrusion (Li et al 2009a, b;Ripley et al 2010). However, sub-economic intrusions with heavy isotopic compositions of S also exist , suggesting that sulfate assimilation is not the only mechanism playing a role in the formation of ore deposits.…”

Section: Introductionmentioning

confidence: 99%

“…The δ 34 S of the sulfide ores is extremely high (9-12.8‰; Li et al 2009 b;Malitch et al 2014), clearly corroborating the crustal provenance of the sulfur. However, the coexistence of the magmatic anhydrite with sulfides suggests an incomplete reduction of the oxidized magma (Ripley et al 2010). The extremely high PGE, Ni, and Cu contents of the massive sulfides (Naldrett 2004) also indicate that not all the sulfur dissolved in the oxidized magma can have been reduced to sulfide.…”

mentioning

confidence: 99%

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Assimilation of sulfate and carbonaceous rocks: Experimental study, thermodynamic modeling and application to the Noril’sk-Talnakh region (Russia)

Iacono-Marziano

Ferraina

Gaillard

et al. 2017

Ore Geology Reviews

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This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. sulfate and organic matter-rich sedimentary rocks has been proposed as a possible mechanism for the origin of these exceptional sulfide deposits but the interaction process and the reaction paths have never been fully investigated. Here we clarify, by both experimental petrology and thermodynamic modeling, how sulfate and organic matter assimilation occur in mafic-ultramafic magmas, affecting magma composition, crystallization and sulfide saturation.Interaction experiments were conducted at conditions relevant to the emplacement of Noril'sk type intrusions (1200 °C, ~80 MPa) to simulate the assimilation of sulfate and/or organic compounds by ultramafic magmas. We used a picrite from Noril'sk1 intrusion, and coal and anhydrite from the area as starting materials. The experimental results show that the incorporation of anhydrite into the magma occurs by chemical dissolution in the melt, which increases the magma's sulfur content, but suppresses sulfide saturation and reduces olivine crystallization. Extreme assimilation leads to sulfate saturation in the magma and high dissolved sulfur contents of 0.9±0.1 wt.% S. Conversely, coal assimilation promotes sulfide segregation and magma crystallization, while decreasing the dissolved H 2 O content of the melt and increasing the amount of coexisting fluid phase.We also employed gas-melt thermodynamic calculations to quantify the effect of these assimilations on the redox conditions and the S content of the magma, and investigate the role of temperature, pressure, and initial gas content of the magma in the assimilation process. We quantify how sulfate assimilation strongly oxidizes the magma and increases its S content; both effects are intensified by 2 increasing pressure (from 50 to 100 MPa in this study), decreasing temperature (from 1350 to 1200 °C in this study), and decreasing amounts of fluid phase initially coexisting with the magma (from 2 to 0 wt.%). The interaction with organic matter (CH in this study) induces a strong reduction of the magma, even for extremely low degrees of assimilation (few tenths of wt. %), and the dehydration of the melt.We therefore suggest that in the Noril'sk-Talnakh district (1) additional S was supplied to mantle derived magmas by the assimilation of evaporitic rocks, and was transported during magma ascent in the form of dissolved, oxidized S; (2) a substantial reduction of the magma inducing sulfide segregation and important crystallization then occurred due to the interaction with carbonaceous sediments. This mechanism can potentially produce massive sulfide deposits by imp...

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Section: Introductionsupporting

confidence: 91%

Section: Introductionmentioning

confidence: 87%

Section: Introductionmentioning

confidence: 99%

mentioning

confidence: 99%

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Assimilation of sulfate and carbonaceous rocks: Experimental study, thermodynamic modeling and application to the Noril’sk-Talnakh region (Russia)

Iacono-Marziano

Ferraina

Gaillard

et al. 2017

Ore Geology Reviews

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“…Samples were analyzed using continuous flow methodology in a Finnigan Delta V stable isotope ratio mass spectrometer at Indiana University Bloomington, USA. Details of the analytical method were reported by Ripley et al (2010). Reference materials NBS-127, IAEA S-1, IAEA S-2 and IAEA S-3 were used as reference standards with values of +20.3‰, −0.3‰, +21.7‰ and −31.3‰, respectively, on the SO 2 -scale.…”

Section: Samples and Analytical Methodsmentioning

confidence: 99%