227 D22. Recent Advances in Precambrian Geology (Posters)

Wednesday, 13 October 2021
9:00 AM - 1:00 PM
Exhibit Hall A

THE MESOPROTEROZOIC OF THE OLENEK UPLIFT, NE SIBERIA

Paper number: 227-10
Program: Technical Sessions
Time: 9:00 AM – 1:00 PM

Authors

Abstract

Mesoproterozoic (1.6–1.0 Ga) is a time of the Earth's history that witnessed the breakup of the supercontinent Columbia and the amalgamation of the Rodinia supercontinent. Starting from the Great Oxygenation Event (GOE ~ 2.4–2.0 Ga), the oxygen level was slowly rising through the Mesoproterozoic. However, it was still not enough to stimulate the high tempo of biological evolution. As a result, the Mesoproterozoic Era is considered as one of the most static intervals of biological evolution, and is often called “boring billion”. Nonetheless, there are still plenty of unknowns that influenced the ecosystem during that time. Here, we present results of a comprehensive study of the Mesoproterozoic succession from the Olenek Uplift, including the sedimentology, chemostratigraphy, redox, and productivity proxies, and paleontology.

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).

Geological Society of America Abstracts with Programs. Vol. 53, No. 6

doi: 10.1130/abs/2021AM-364311

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