The partitioning of chalcophile elements between sediment melts and fluids at 3 GPa, 950–1050 °C with implications for slab fluids in subduction zones

D’Souza, Rameses J.; Canil, Dante

doi:10.1016/j.epsl.2018.06.037

Cited by 16 publications

(4 citation statements)

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“…Grt , garnet; Ky, kyanite; Po, pyrrhotite ; Opx, orthopyroxene; Bt, biotite. and ƒO 2 = FMQ-4 to FMQ+3.5 (Prouteau & Scaillet, 2013;Jégo & Dasgupta, 2013, 2014Canil & Fellows, 2017;D'Souza & Canil, 2018).…”

Section: Discussionmentioning

confidence: 99%

“…Vertical bars are 1 standard deviation (when not shown error bars are smaller than the symbol size). Grey symbols show the sulphur content of experimental silicic glasses saturated in sulphide and/or sulphate at 2.3-3 GPa, 700 to 1100°C and ƒO 2 = FMQ-4 to FMQ+3.5 (Prouteau & Scaillet, 2013;Jégo & Dasgupta, 2013, 2014Canil & Fellows, 2017;D'Souza & Canil, 2018). B12a: Ca-poor pelite with 1-4 wt.…”

Section: Figure Captionsmentioning

confidence: 99%

“…Luhr, 1990;Carroll & Webster, 1994;Scaillet et al, 1998), and consequently silicate melts were usually considered not to be an efficient agent of sulphur extraction from the slab. However, experimental works have demonstrated that the sulphur content of high pressure oxidized hydrous silicic melts is at least 10-20 times higher than at low pressures (Prouteau & Scaillet, 2013;Jégo & Dasgupta, 2014;Canil & Fellows, 2017;D'Souza & Canil, 2018;Li et al, 2019). This finding reduces the restriction that the sulphur-rich character of present-day arc volcanism bears evidence solely of a sulphur-rich hydrous fluid.…”

Section: Introductionmentioning

confidence: 96%

“…Sulphur has been shown to affect the stabilities of phases other than those S-bearing, i.e. amphibole, biotite in magmas (Scaillet & Evans, 1999;Costa et al, 2004;Prouteau & Scaillet, 2013;Canil & Fellows, 2017;D'Souza & Canil, 2018). It is thus important to assess the role of S on the stability of phases of subducted sediments in order to evaluate its potential effect on trace element patterns.…”

Section: Introductionmentioning

confidence: 99%

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The Role of Sulphur on the Melting of Ca-Poor Sediment and on Trace Element Transfer in Subduction Zones: An Experimental Investigation

Pelleter

Prouteau

Scaillet

2021

Journal of Petrology

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We performed phase equilibrium experiments on a natural Ca-poor pelite at 3 GPa, 750-1000 °C, under moderately oxidizing conditions, simulating the partial melting of such lithologies in subduction zones. Experiments investigated the effect of sulphur addition on phase equilibria and compositions, with S contents of up to ∼ 2.2 wt. %. Run products were characterized for their major and trace element contents, in order to shed light on the role of sulphur on the trace element patterns of melts produced by partial melting of oceanic Ca-poor sediments. Results show that sulphur addition leads to the replacement of phengite by biotite along with the progressive consumption of garnet, which is replaced by an orthopyroxene-kyanite assemblage at the highest sulphur content investigated. All Fe-Mg silicate phases produced with sulphur, including melt, have higher MgO/(MgO+FeO) ratios (relative to S-free/poor conditions), owing to Fe being primarily locked up by sulphide in the investigated redox range. Secular infiltration of the mantle wedge by such MgO and K2O-rich melts may have contributed to the Mg and K-rich character of the modern continental crust. Addition of sulphur does not affect significantly the stability of the main accessory phases controlling the behaviour of trace elements (monazite, rutile and zircon), although our results suggest that monazite solubility is sensitive to S content at the conditions investigated. The low temperature (∼ 800 °C) S-bearing and Ca-poor sediment sourced slab melts show Th and La abundances, Th/La systematics and HFSE signatures in agreement with the characteristics of sediment-rich arc magmas. Because high S contents diminish phengite and garnet stabilities, S-rich and Ca-poor sediment sourced slab melts have higher contents of Rb, B, Li (to a lesser extent), and HREE. The highest ratios of La/Yb are observed in sulphur-poor runs (with a high proportion of garnet, which retains HREE) and beyond the monazite out curve (which retains LREE). Sulphides appear to be relatively Pb-poor and impart high Pb/Ce ratio to coexisting melts, even at high S content. Overall, our results show that Phanerozoic arc magmas from high sediment flux margins owe their geochemical signature to the subduction of terrigenous, sometimes S-rich, sediments. In contrast, subduction of such lithologies during Archean appears unlikely or unrecorded.

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