Carbon and oxygen isotopes in the Frasnian-Famennian section of the Kuznetsk basin (southern West Siberia)
O.P. Izokh a ,*, N.G. Izokh b , V.A. Ponomarchuk a , D.V. Semenova a
a Sobolev Institute of Geology and Mineralogy, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
b Trofimuk Institute of Petroleum Geology and Geophysics, Siberian Branch of the RAS, 3 prosp. Akad. Koptyuga, Novosibirsk, 630090, Russia
Keywords: isotopes; carbon; oxygen; carbonates; Famennian Stage; Upper Devonian; northwestern Kuznetsk Basin
Pages: 602-609
Abstract
The first detailed isotope-geochemical study of carbonate deposits has been performed in the Lower Famennian stratotype section of the northwestern Kuznetsk Basin (Kosoy Utyos), which was localized in the middle latitudes of the Northern Hemisphere in the Late Devonian. The δ13 Cкарб, δ13 Cорг and δ18 variation curves were constructed for the section deposits. Geochemical and petrographic studies of carbonates allowed allocation of samples that underwent postsedimentation alteration and exclude them from further interpretation. Compared with coeval sections in the other world's regions, the Kosoy Utyos section is characterized by higher δ13 Ccarb values, up to 5.4 ‰, whereas the maximum value in subequatorial area sections is 4 ‰. The isotope shift amplitude of the studied section reaches 4.6 ‰, which is 1.5 ‰ higher than those in other regions. The δ18O values are 3 ‰ lower than the ones of the world's coeval sections. The results obtained show that δ13C and δ18O variation trends differ from those of coeval subequatorial sections. The high shift amplitude and maximum δ13 Ccarb values in the Kosoy Utyos section are due to the shallow-water carbonate sedimentation environments on the Siberian continental shelf and, probably, the lower temperatures of waters in the middle latitudes as compared with the subequatorial areas.
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