Detrital tourmaline from the riphean terrigenous deposits of the Middle Timan: сhemical composition and genesis
Brusnitsyna Е. А., Vereshchagin O. S., Ershova V. B.
Zapiski RMO (Proceedings of the Russian Mineralogical Society). 2022. V. 151. N 1. P. 29-43
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Data on the chemical composition and the degree of roundness of detrital tourmaline from the Chetlasskaya, Bystrinskaya, Vymskaya, and Kislorucheyskaya group of Upper Precambrian metaterrigenous rocks of the Middle Timan are presented. Fragments of the studied tourmaline crystals are predominantly homogeneous (without visible concentric and sectorial zoning) and belong to the alkaline group and hydroxy subgroup (dravite and shorl) of the tourmaline supergroup. The similarity in chemical compositions indicates a single source of fragments of this mineral for all studied Riphean sedimentary rocks within the studied region, and the low degree of roundness indicates the proximity of the primary source. Comparison of tourmaline with associated detrital zircon made it possible to conclude that the source of clastic material for the formation of metaterrigenous rocks of the Upper Precambrian in the Middle Timan was metamorphic complexes in the terrains of the Grenvillian-Sveconorwegian Orogen.
Keywords: Middle Timan, Riphean, tourmaline, zircon, heavy minerals