Immiscible sulfide melts in primitive oceanic magmas: Evidence and implications from picrite lavas (Eastern Kamchatka, Russia)

Savelyev, D. P.; Kamenetsky, Vadim S.; Danyushevsky, Leonid V.; Botcharnikov, Roman E.; Kamenetsky, Maya B.; Park, Jung‐Woo; Portnyagin, Maxim; Olin, P; Krasheninnikov, Stepan Petrovich; Hauff, Folkmar; Zelenski, Michael

doi:10.2138/am-2018-6352

Cited by 31 publications

(29 citation statements)

References 41 publications

(65 reference statements)

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“…These sulphide types are similar to those found in MORBs (e.g. Patten et al, 2012, Keith et al, 2017, Savelyev et al, 2018 references therein) and represent only a first stage sulphide saturation. From textural evidence, e.g., decompression rims in amphibole (Fig.5c), complex textures of cubanite-chalcopyrite resulting from rapid 325 unmixing of iss due to T drop (Fig.5d, type-3) as well as the intact sulphide aggregates found in the groundmass (figure 5e, type 6), the magma in Kula seems to have ascended fast from depth (e.g.…”

supporting

confidence: 79%

“…Although this decrease in Ni/Cu has been noted previously by other researchers (e.g. Hattori, 1999, Du et al, 2014, Keith et al, 2017, Savelyev et al, 2018 310 for the early sulphides, until now, there has not been a systematic study on the later stage, iss-only sulphides. The reason for this is most likely the fact that the majority of past studies on sulphides have focussed on silicate mineral separates, in order to be able to locate and analyse the bulk chemistry of entrapped sulphides.…”

mentioning

confidence: 54%

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Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Georgatou

Chiaradia

2019

Preprint

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Abstract. We investigate in both mineralised and barren systems the occurrence and chemistry of magmatic sulphides and their chalcophile metal cargo behaviour during evolution of compositionally different magmas in diverse geodynamic settings. The investigated areas are: (a) the Miocene Konya magmatic province (hosting the Doganbey Cu-Mo and Inlice Au-epithermal deposits) (Post-Subduction) and (b) the Miocene Usak basin (Elmadag, Itecektepe and Beydagi volcanoes, the latter associated with the Kisladag Au porphyry) in Western Turkey (Post-Subduction). For comparison we also investigate (c) the barren Plio-Quaternary Kula volcanic field, west of Usak (Intraplate) and finally we discuss and compare all the above areas with the already studied (d) Quaternary Ecuadorian volcanic arc (host to the Miocene Llurimagua Cu-Mo and Cascabel Cu-Au porphyry deposits) (Subduction). The volcanism of the studied areas displays a wide range of SiO2 spanning from basalts to andesites/dacites and from high K-calc-alkaline to shoshonitic series. Multiphase magmatic sulphides occur in different amounts in all investigated areas and based on textural and compositional differences, they can be classified in different types, which crystallised at different times (early versus late saturation). A decrease in the sulphide Ni/Cu (proxy for mss-monosulphide solid solution/iss-intermediate solid solution) ratio is noted with magmatic evolution. Starting with an early stage, saturating Ni-richer/Cu-poorer sulphides hosted by early crystallising minerals e.g. olivine/pyroxene, leading up to a later stage, producing Cu-richer sulphides hosted by magnetite. The most common sulphide type resulting from an early saturating stage is composed of a Cu-poor/Ni-rich (pyrrhotite/mss) and one/two Cu-rich (cubanite, chalcopyrite/iss) phases making up 84 and 16 area % of the sulphide, respectively. Our results suggest that independently of the magma composition, geodynamic setting and whether or not the system has generated an ore deposit on the surface, sulphide saturation occurred in variable degrees in all studied areas and magmatic systems and is characterised by a similar initial metal content of the magmas. However not all studied areas present all sulphide types and the sulphide composition is dependent on the nature of the host mineral. In particular sulphides, resulting from the late stage, consisting of Cu-rich phases (chalcopyrite ,bornite, digenite/iss) are hosted exclusively by magnetite and are found only in magmatic provinces associated with porphyry Cu (Konya and Ecuador) and porphyry Au (Beydagi) deposits.

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supporting

confidence: 79%

mentioning

confidence: 54%

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Georgatou

Chiaradia

2019

Preprint

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“…There is no correlation between sulfide-liquid partition coefficients and emanation coefficients defined using petrology, or aerosol chemistry. Métrich et al, 1999;Savelyev et al, 2018). As Kīlauean liquids undergoing only olivine (+ minor chromite) fractionation have near-constant FeO contents (∼11.33 wt%), the extent of Fe-loss is inversely proportional to the measured FeO content of the melt inclusion.…”

Section: Sulfide Resorption During Magma Degassingmentioning

confidence: 99%

Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai’i

Wieser

Jenner

Edmonds

et al. 2020

Geochimica et Cosmochimica Acta

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Chalcophile element concentrations in melt inclusions and matrix glasses may be used to investigate low pressure degassing processes, as well as sulfide saturation during crustal fractionation, and mantle melting. Erupted products from Kīlauea Volcano, Hawaii record three stages of sulfide saturation (in the mantle, crust, and within lava lakes), separated by episodes of sulfide resorption (i.e., sulfide undersaturation) during ascent through the thick Hawaiian lithosphere, and during syn-eruptive degassing. The presence of residual sulfides in the mantle source throughout the melting interval accounts for the high S concentrations of Kīlauean primary melts (1387-1600 ppm). Residual sulfides retain chalcophile elements during melting, decoupling the variability of these elements in high MgO melts from that of lithophile elements. Decompression associated with magma ascent through the thick Hawaiian lithosphere drives an increase in the sulfide concentration at sulfide saturation (SCSS 2−), resulting in shallow storage reservoirs (∼1-5 km depth) being supplied with sulfide-undersaturated melts. A drop in temperature, coupled with major element changes during the fractionation of olivine, causes the SCSS 2− to decrease. Combined with an increase in melt S contents during fractionation, this initiates a second stage of sulfide saturation at relatively high MgO contents (∼12 wt%). Syn-eruptive degassing of S drives the resorption of sulfides in contact with the carrier liquid. The covariance structure of Cu, MgO and Ni contents in melt inclusions and matrix glasses indicates that the dissolution of sulfides effectively liberates sulfide-hosted Cu and Ni back into the melt, rather than the vapour phase. The contrasting behaviour of Cu, Ni, Se and S during sulfide resorption indicates that the chalcophile element signature of the Kīlauean plume is largely controlled by silicate melt-vapour partitioning, rather than sulfide-vapour partitioning. The participation of dense sulfide liquids in shallow degassing processes may result from their direct attachment to buoyant vapour bubbles, or olivine crystals which were remobilized prior to eruption. Sulfide resorption obscures the textural and chemical record of sulfide saturation in matrix glasses, but not in melt inclusions, which are isolated from this late-stage release of chalcophile elements. The partitioning of S between the dissolving sulfide, melt and the vapour phase accounts for approximately 20% of the total S release into the atmosphere.

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“…Many examples of immiscibility within natural magmatic systems are known, and compositional differences resulting from unmixing can be extreme (e.g., [106]), potentially creating redox gradients. Immiscibility between felsic and mafic silicate liquids has been documented in layered mafic intrusions, anorthosite complexes, mid-ocean ridge magma chambers, and granitoids (e.g., [107]).…”

Section: Prebiotic Redox Gradients On Earthmentioning

confidence: 99%

“…Even in situations in which one immiscible phase is volumetrically minor compared to the other, it may be extremely effective in extracting and transporting large amounts of trace and rare elements, such as the case for immiscible sulfide melts concentrating PGEs and other chalcophile elements such as Cu and Ni from a larger silicate melt body [106,108,109,110]. The more reduced sulfide melts, segregated from more oxidized silicate melts, are commonly called upon as an important ore-forming process in magmatic Ni-Cu ± PGE deposits [110,111,112,113,114,115,116].…”

Section: Prebiotic Redox Gradients On Earthmentioning

confidence: 99%

The Paleomineralogy of the Hadean Eon Revisited

Morrison

Runyon

Hazen

2018

Life

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A preliminary list of plausible near-surface minerals present during Earth’s Hadean Eon (>4.0 Ga) should be expanded to include: (1) phases that might have formed by precipitation of organic crystals prior to the rise of predation by cellular life; (2) minerals associated with large bolide impacts, especially through the generation of hydrothermal systems in circumferential fracture zones; and (3) local formation of minerals with relatively oxidized transition metals through abiological redox processes, such as photo-oxidation. Additional mineral diversity arises from the occurrence of some mineral species that form more than one ‘natural kind’, each with distinct chemical and morphological characteristics that arise by different paragenetic processes. Rare minerals, for example those containing essential B, Mo, or P, are not necessary for the origins of life. Rather, many common minerals incorporate those and other elements as trace and minor constituents. A rich variety of chemically reactive sites were thus available at the exposed surfaces of common Hadean rock-forming minerals.

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Immiscible sulfide melts in primitive oceanic magmas: Evidence and implications from picrite lavas (Eastern Kamchatka, Russia)

Cited by 31 publications

References 41 publications

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Magmatic sulphides in high-K calc-alkaline to shoshonitic and alkaline rocks

Chalcophile elements track the fate of sulfur at Kīlauea Volcano, Hawai’i

The Paleomineralogy of the Hadean Eon Revisited

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