Isotopic composition of carbon and oxygen in the Riphean carbonate rocks of the Karuyarvin suite of the Sredny peninsula (north framing of the Kola peninsula)

The isotopic composition of carbon and oxygen in the Upper Riphean Dolomites (often stromatolite) from the section of the Karuyarvin Suite exposed along the NorthEastern coast of the Sredny Peninsula in the North of the Kola Peninsula was studied. The results of petrographic studies have shown that sedimentary rocks have not undergone significant postsedimentation transformations, which means that the isotope data are close to the primary Cisotope signal. As a whole, for the section of the Karuyarvin Suite characteristic aremoderately low values of δ13C = -2,9 …-13,7 ‰ (δ13Caverage = -4 ‰) and typical for marine sedimentary rocks δ18O = 21,9 … 27,8 ‰ (δ18Oaverage = 26 ‰). Detailed correlation of the section of theKaruyarvin Suite with the Upper Pre-Cambrian carbonate complexes of the Timan and South Urals is difficult due to the relatively low amplitude (1-2‰) of the δ13C and δ18O excursus. Isotopecarboncurves in the Upper Riphean sediments of the Sredny Peninsula and Chetlass and TsilmenKamens are in general similar, however, the Timan carbonates were heavier in carbon (δ13Caverage = - 1,2 ‰). Given the moderately low values of δ13Cin the Dolomites of the Karuyarvin Suite, it correlates with a sharp negative excursus δ13C in the upper part of the Minyar Suite in the South Urals.