Composition, crystallization conditions and genesis of sulfide-saturated parental melts of olivine-phyric rocks from Kamchatsky Mys (Kamchatka, Russia).

Korneeva, Alina A., Nekrylov, Nikolai A., Kamenetsky, Vadim S., Portnyagin, Maxim V. , Savelyev, Dmitry P., Krasheninnikov, Stepan P., Abersteiner, Adam, Kamenetsky, Maya B., Zelenski, Michael E., Shcherbakov, Vasily D. and Botcharnikov, Roman E. (2020) Composition, crystallization conditions and genesis of sulfide-saturated parental melts of olivine-phyric rocks from Kamchatsky Mys (Kamchatka, Russia). Open Access Lithos, 370-371 (Article number 105657). DOI 10.1016/j.lithos.2020.105657.

[thumbnail of Creative Commons Attribution Non-Commercial No Derivatives License]
Preview
Text (Creative Commons Attribution Non-Commercial No Derivatives License)
2020-Korneeva-Lithos-KamMys_Pre-Proof.pdf - Accepted Version

Download (17MB) | Preview
[thumbnail of 2020-Korneeva-Lithos_KamMys_SupplementaryFiles.zip] Archive
2020-Korneeva-Lithos_KamMys_SupplementaryFiles.zip - Supplemental Material

Download (294kB)

Supplementary data:

Abstract

Highlights

• Parental melts of sulfide-bearing KM rocks have near primary MORB-like composition.
• Crystallization of these S-saturated melts occurred in near-surface conditions.
• Extensive fractionation and crustal assimilation are not the causes of S-saturation.
• S content in melts can be restored by accounting for daughter sulfide globules.

Abstract

Sulfide liquids that immiscibly separate from silicate melts in different magmatic processes accumulate chalcophile metals and may represent important sources of the metals in Earth's crust for the formation of ore deposits. Sulfide phases commonly found in some primitive mid-ocean ridge basalts (MORB) may support the occurrence of sulfide immiscibility in the crust without requiring magma contamination and/or extensive fractionation. However, the records of incipient sulfide melts in equilibrium with primitive high-Mg olivine and Cr-spinel are scarce. Sulfide globules in olivine phenocrysts in picritic rocks of MORB-affinity at Kamchatsky Mys (Eastern Kamchatka, Russia) represent a well-documented example of natural immiscibility in primitive oceanic magmas. Our study examines the conditions of silicate-sulfide immiscibility in these magmas by reporting high precision data on the compositions of Cr-spinel and silicate melt inclusions, hosted in Mg-rich olivine (86.9–90 mol% Fo), which also contain globules of magmatic sulfide melt. Major and trace element contents of reconstructed parental silicate melts, redox conditions (ΔQFM = +0.1 ± 0.16 (1σ) log. units) and crystallization temperature (1200–1285 °C), as well as mantle potential temperatures (~1350 °C), correspond to typical MORB values. We show that nearly 50% of sulfur could be captured in daughter sulfide globules even in reheated melt inclusions, which could lead to a significant underestimation of sulfur content in reconstructed silicate melts. The saturation of these melts in sulfur appears to be unrelated to the effects of melt crystallization and crustal assimilation, so we discuss the reasons for the S variations in reconstructed melts and the influence of pressure and other parameters on the SCSS (Sulfur Content at Sulfide Saturation).

Document Type: Article
Keywords: magmatic sulphide; melt inclusion; MORB; Kamchatka
Research affiliation: OceanRep > GEOMAR > FB4 Dynamics of the Ocean Floor > FB4-MUHS
Refereed: Yes
Open Access Journal?: No
Publisher: Elsevier
Date Deposited: 08 Jul 2020 07:22
Last Modified: 08 Feb 2023 09:30
URI: https://oceanrep.geomar.de/id/eprint/50083

Actions (login required)

View Item View Item