Sulfur Isotope Composition of Ru–Os Sulfides from the Guli Massif, Maimecha-Kotui Province, Russia: First Results

• Published in: Doklady earth sciences Vol. 507; no. 2; pp. 1013 - 1019
• Main Authors: Malitch, K. N., Kogarko, L. N., Badanina, I. Yu, Velivetskaya, T. A., Ignatiev, A. V.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 01-12-2022; Springer; Springer Nature B.V
• Subjects: Ablation; Alloys; Analysis; Analytical methods; Dunite; Earth and Environmental Science; Earth Sciences; Electron microprobe; Electron probe microanalysis; Electron probes; Geochemistry; Inclusions; Iridium; Iridium base alloys; Isotope composition; Isotopes; Laser ablation; Lasers; Massifs; Osmium; Platinum; Quaternary deposits; Ruthenium; Solid solutions; Spectrometry; Sulfides; Sulfur; Sulfur isotopes; Sulphides; Sulphur; Ru–Os sulfides; laurite; sulfur isotope composition; near-chondritic source; Guli massif; erlichmanite; Maimecha-Kotui province
• ISSN: 1028-334X; 1531-8354
• DOI: 10.1134/S1028334X22600955

To gain further insight into the origin of Ru–Os sulfides, the first in-situ sulfur isotopic data for Ru–Os sulfides from different polyphase platinum-group mineral (PGM) assemblages derived from the Quaternary deposits of the Guli massif located in the Maimecha-Kotui province are presented. A number of analytical techniques, including electron microprobe analysis and laser ablation attached to multiple-collector inductively coupled-plasma mass-spectrometry, were utilized. Polyphase platinum-group mineral (PGM) assemblages are represented by two types: (1) osmium and iridium alloys associated with Ru–Os sulfides of the laurite (Ru,Os)S
2
–erlichmanite (Os,Ru)S
2
solid solution series, cuproiridsite (CuIr
2
S
4
), and unnamed Os–Ir sulfide (Os,Ir)S
2
; (2) ferroan platinum containing inclusions of laurite, Ru–Os–Ir alloys, and other PGMs. These detrital PGM assemblages were sourced from different bedrocks. It is concluded that PGM assemblages of types 1 and 2 were derived from dunite/chromitite and clinopyroxenite, respectively. The sulfur isotope signatures of Ru–Os sulfides of type 1 (δ
34
S = 0.9 ± 0.4‰,
n
= 8) imply that sulfur derived from a subchondritic source. The slightly lighter δ
34
S values in type 2 laurite (δ
34
S = –1.7 ± 0.2‰,
n
= 10) are likely due to the evolved composition of the ore-forming fluid. Despite these differences, the S-isotope data are consistent with the origin of sulfur from a common near-chondritic source.