Sulfur isotopic compositions of the lithospheric mantle sulfides from the Udachnaya pipe (Yakutia)
- 1Sobolev Institute of Geology and Mineralogy, The laboratory of lithospheric mantle and diamond deposits, Novosibirsk, Russian Federation (olgailyina88@gmail.com)
- 2Université Jean Monnet, Unité de Recherche Magmas et Volcans, Saint-Etienne, France
Sulfide inclusions in Neoproterozoic West African diamonds have revealed mass-independently fractionated sulfur isotopes in them [Smit et.al., 2019]. This feature is a sign of Archean surface changes traced in the mantle. Here we present an S isotope study of the unique fresh mantle deep-seated peridotites, eclogites and pyroxenites with rare or without any secondary alterations from the Udachnaya-East pipe. This research will give better understanding the role of subduction in the formation of the lithospheric mantle under the Siberian craton. Sulfur isotopes (34S/32S which is denoted as δ34S) were measured in the sulfides from eclogites, peridotites and pyroxenites using an Isoprime isotope ratio mass spectrometer (IRMS) with classic configuration with 4 collectors. The sulfides from eclogites are pyrrotite, pentlandites and chalcopyrites. They have δ34S values from +0,67 to +3,08 per mil (‰). Sulfides in peridotites are pyrrotite-pentlandite-chalcopyrites assemblages and they have δ34S values from +0,22 to +3,55 ‰. These δ34S values from eclogites and peridotites are broadly overlap with the field for depleted mantle and chondrites (-1,9 to +0,35‰) [Labidi et.al., 2013; 2014]. Sulfides from pyroxenites are pyrrotite and they have δ34S values from -3,62 to +1,49 ‰. These δ34S values have a wider range than the estimates for depleted mantle. The δ34S values in our samples are close to those in the depleted mantle, but still have deviation from it and do not fractionated. Our data did not detect mass-independently fractionated sulfur isotopes in the mantle samples from the Udachnaya pipe. Thus subduction of the earth’s crust did not play role in the values of sulfur isotopes of the lithospheric mantle sampled by Udachnaya kimberlite pipe. The source of sulfur in these rocks probably was the astenospheric mantle.
References
- Smit et. al., 2019
- Labidi et. al., 2013; 2014
This study was supported by the Russian Foundation for Basic Research № 18-05-70064
How to cite: Ilyina, O., Agashev, A., and Moine, B.: Sulfur isotopic compositions of the lithospheric mantle sulfides from the Udachnaya pipe (Yakutia), EGU General Assembly 2020, Online, 4–8 May 2020, EGU2020-21171, https://doi.org/10.5194/egusphere-egu2020-21171, 2020
