THE MESOPROTEROZOIC OF THE OLENEK UPLIFT, NE SIBERIA
The studied interval includes the Arymas, Debengda, and Khaipakh formations of the Sololi Group, Olenek Uplift. The known geochronological ages from the globular phyllosilicates are 1.30 Ga, 1,28–1.26, and 1.17–1.12 respectively, and they support the Mesoproterozoic age.
The Olenek Uplift Mesoproterozoic succession consists of the mixed carbonate-siliciclastic rocks, the overall thickness is ~ 1.5 rm. The sedimentological research allowed identifying the sequences inside of the succession. The iron speciation analysis demonstrates the changing water redox conditions from the predominantly oxic shallower waters to the ferruginous ones in the distal parts of the basin. The oxic intervals often preserve various microbial structures, including the Horodyskia fossils. The redox proxies, such as Cr/Al, V/Al, Mo/Al, Re/Al, U/Al, in general, are following the trends of the iron speciation data. The carbonate carbon isotopic curve (from the carbonate intervals of the succession) varies from +1.1 to -2.7 δ13C, but in most cases close to 0 δ13C. In the 4th Member of the Khaipakh Fm, there is a negative excursion (down to -2.7 δ13C, which could be correlated with analogous ones in Canada, West Africa, and Siberia, although the age models are not perfect.
The research was funded by RFBR # 19-05-01006, 18-05-70110, RFS # 21-17-00052, and government contract 0331-2019-0002 (Ministry of Education and Science of the Russian Federation).