Sulfur extraction via carbonated melts from sulfide-bearing mantle lithologies – Implications for deep sulfur cycle and mantle redox

Chowdhury, Proteek; Dasgupta, Rajdeep

doi:10.1016/j.gca.2019.11.002

Cited by 31 publications

(38 citation statements)

References 99 publications

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“…As such, melt saturation in CO 2 and S, as well as separation of CO 2 -rich fluids and sulfide liquids in the mantle, are necessarily restricted to low-degree melting regimes (<10%), and therefore alkaline mafic/ultramafic melts. The recent experimental work of Chowdury and Dasgupta 61 on the concentration of S at sulfide saturation in carbonate-rich silicate melts provides a potential theoretical framework in support of our hypothesis. Assimilation of silicate mantle wall rocks ubiquitously affect CO 2 -rich silicate magmas during their ascent through the lithospheric mantle 62 , 63 .…”

Section: Discussionsupporting

confidence: 69%

“…At pressure ≥3.5 GPa (~100-110 km of depth), interaction of carbonate-rich melts and peridotite wall rocks (especially orthopyroxene) can drive out large amounts of CO 2 from ascending melts and generate CO 2 -rich supercritical fluids 64 . A large drop in CO 2 and related increase in SiO 2 contents above 35-40% largely decrease the solubility of reduced S and promotes the formation of immiscible sulfide melts 61 as well. What remains to be addressed is whether or not CO 2 -rich supercritical fluids and sulfide melts can remain physically connected during ascent once exsolved from their parental silicate magma.…”

Section: Discussionmentioning

confidence: 99%

“…Experimental studies by Woodland et al 65 have shown that silicate-carbonatitic melts in the mantle are able to dissolve and transport significant S; however, when mantle-derived magmas are sulfide supersaturated in the deepest portions of the lithosphere, chalcophile metals will be largely transported in sulfide droplets 30,61,66 . Following low-degree partial melting producing carbonate-rich alkaline melts, silica contamination would trigger both CO 2 and sulfide supersaturation in the melt (Fig.…”

Section: Discussionmentioning

confidence: 99%

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Fluxing of mantle carbon as a physical agent for metallogenic fertilization of the crust

et al. 2020

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Magmatic systems play a crucial role in enriching the crust with volatiles and elements that reside primarily within the Earth's mantle, including economically important metals like nickel, copper and platinum-group elements. However, transport of these metals within silicate magmas primarily occurs within dense sulfide liquids, which tend to coalesce, settle and not be efficiently transported in ascending magmas. Here we show textural observations, backed up with carbon and oxygen isotope data, which indicate an intimate association between mantle-derived carbonates and sulfides in some mafic-ultramafic magmatic systems emplaced at the base of the continental crust. We propose that carbon, as a buoyant supercritical CO 2 fluid, might be a covert agent aiding and promoting the physical transport of sulfides across the mantle-crust transition. This may be a common but cryptic mechanism that facilitates cycling of volatiles and metals from the mantle to the lower-to-mid continental crust, which leaves little footprint behind by the time magmas reach the Earth's surface.

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Section: Discussionsupporting

confidence: 69%

Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

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Fluxing of mantle carbon as a physical agent for metallogenic fertilization of the crust

et al. 2020

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“…However, the high Fe 3+ /ΣFe of nephelinites and alkaline basalts in eastern China strongly suggests that they originated from mantle sources which are more oxidized than the MORBs (average Fe 3+ /ΣFe = 0.16 ± 0.01; Cottrell & Kelley, 2011). Increasing f O2 can dramatically increase the sulfur content at sulfide saturation (SCSS) and thus enhance sulfide dissolution (Chowdhury & Dasgupta, 2020; Ding & Dasgupta, 2017; Jugo et al., 2010; Wallace & Carmichael, 1992). We envisage that in the presence of sulfide in mantle (either in crystalline or molten phase), silicate melts dissolve sulfide rapidly.…”

Section: Discussionmentioning

confidence: 99%

“…The α melt-Ol is set as 1.00015 according to the upper bound of α melt-Ol from Klaver et al (2020). Sulfur content at sulfide saturation (SCSS) model is from Chowdhury and Dasgupta (2020) and Jugo et al (2010). The basaltic melt composition used in SCSS calculation is from Gale et al (2013).…”

Section: Nickel Isotopic Variations In Mafic Lithologiesmentioning

confidence: 99%

Sulfide Dissolution on the Nickel Isotopic Composition of Basaltic Rocks

et al. 2022

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Experimental Investigation on the Transport of Sulfide Driven by Melt-rock Reaction in Partially Molten Peridotite

Wang

Yao

Zhou

et al. 2023

Preprint

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Extraction of sulfides from the partially molten mantle is vital to elucidate the cycling of metal and sulfur elements between different geochemical circles but has not been investigated systematically. Using laboratory experiments and theoretical calculations, this study documents systematical variations in lithologies and compositions of silicate minerals and melts, which are approximately consistent with the results of the thermodynamically-constrained model. During a melt-peridotite reaction, the dissolution of olivine and precipitation of new orthopyroxene generate an orthopyroxene-rich layer between the melt source and peridotite. With increasing reaction degree, more melt is infiltrated into and reacts with upper peridotite, which potentially enhances the concomitant upward transport of dense sulfide droplets. Theoretical analyses suggest an energetically focused melt flow with a high velocity (~ 170.9 μm/h) around sulfide droplets through the pore throat. In this energic melt flow, we, for the first time, observed the mechanical coalescence of sulfide droplets, and the associated drag force was likely driving upward entrainment of fine μm-scale sulfide. For coarse sulfide droplets whose sizes are larger than the pore throat in the peridotite, their entrainment through narrow constrictions in crystal framework seems to be physically possible only when high-degree melt-peridotite reaction drives high porosity of peridotite and channelized melt flows with extremely high velocity. Hence, the melt-rock reaction could drive and enhance upward entrainment of μm- to mm-scale sulfide in the partially molten mantle, potentially contributing to the fertilization of the sub-continental lithospheric mantle and the endowment of metal-bearing sulfide for the formation of magmatic sulfide deposits.

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Sulfur extraction via carbonated melts from sulfide-bearing mantle lithologies – Implications for deep sulfur cycle and mantle redox

Cited by 31 publications

References 99 publications

Fluxing of mantle carbon as a physical agent for metallogenic fertilization of the crust

Fluxing of mantle carbon as a physical agent for metallogenic fertilization of the crust

Sulfide Dissolution on the Nickel Isotopic Composition of Basaltic Rocks

Experimental Investigation on the Transport of Sulfide Driven by Melt-rock Reaction in Partially Molten Peridotite

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