This study presents the first sulfur isotope data collected for sulfides (pyrrhotite, pyrite, chalcopyrite, djerfisherite, sphalerite, alabandine and valleriite) from carbonatite series rocks of the Guli alkaline-ultramafic massif (Maimecha–Kotui province) using local femtosecond laser ablation and mass spectrometry. Alabandine, manganese-rich wurtzite, and iron-rich sphalerite are sequentially crystallized in polyphase sulfide assemblages of phoscorites and carbonatites. It was established that wurtzite crystallization began at a temperature of 660°C and terminated at 450°C. The sulfur isotope composition (δ34S) of sulfide minerals from phoscorites varies from –3.0 to –5.8‰ (n = 24), with the exception of two analyses of Ni-bearing pyrite, characterized by a higher δ34S value of –1.6 ± 0.14‰. For sulfides from carbonatite, a consistent shift towards lower δ34S values has been revealed (δ34S from –3.9 to –6.9 ‰, n = 22), which is typical for hydrothermal (carbothermal) environments. The δ34S values for the most common sulfides—pyrrhotite, djerfisherite, pyrite—show different ranges and decrease from early to late generations, which is explained by an increase in the degree of oxidation and a decrease in the temperature of the carbonatite melt during the successive crystallization of phoscorite and carbonatites. The sulfur isotope composition of sulfides from carbonatite series rocks is indicative of a magma-derived fluid source. No isotopic values characteristic of the transition of sulfur from the sulfide to the sulfate state have been detected.
Malitch et al. (Sun,) studied this question.