Cenozoic deposits of western Kotel’nyi Island (New Siberian Islands): key insights into the tectonic evolution of the Laptev Sea

ABSTRACT

The Arctic sedimentary basins are still poorly studied in comparison with other regions. The lack of deep wells across the eastern Russian Arctic has resulted in numerous contrasting geodynamic models for the geological evolution and age of sedimentary successions within this frontier region, where a modern mid-ocean ridge breaks through the continental crust in the Laptev Sea. The only onshore evidence of rifting processes is a number of small graben-like depressions exposed on the New Siberian Islands and along the Laptev Sea coast. We present U-Pb detrital zircon provenance and palynology study results of the Cenozoic sedimentary rocks filling graben-like depressions across western Kotel’nyi Island. Palynological data indicate that these sedimentary rocks are Early Eocene to Pleistocene in age. Based on U-Pb detrital zircon dating, Early Eocene and Late Oligocene clastic sediments were sourced from underlying deformed Palaeozoic rocks as well as by reworking of Upper Mesozoic rocks outcropping elsewhere on Kotel’nyi Island, which bear Siberian signature. Plio-Pleistocene clastic sediments were not derived from the erosion of deformed Palaeozoic rocks, suggesting the cessation of active uplift by this time and the development of a regional peneplain. Therefore, by extrapolating our onshore observations to the neighbouring offshore, we propose that graben structures imaged by seismic profiles along the eastern flank of the Laptev Rift System are likely to host Eocene and Oligocene sediments. Thus, it implies the Cenozoic extension led to formation of grabens on- and offshore in the eastern portion of Laptev Sea as early as Eocene. Further studies are necessary to evaluate the age of graben-related basins in the central and western part of the Laptev Sea.

KEYWORDS:

• Laptev Sea
• Arctic
• Cenozoic
• rifts
• New Siberian Islands

Acknowledgments

The fieldwork and analytical analyses were supported by project of Clapton Research Inc. Interpretation of isotopic data was supported by the Russian Science Foundation grant no. 20-17-00169. The study of A.Khudoley was supported by Ministry of Science and Higher Education of the Russian Federation grant 075-15-2022-1100. Valuable reviews by Prof. Victoria Pease, anonymous reviewer and editor Dr. Robert J. Stern significantly improved the manuscript.

Disclosure statement

No potential conflict of interest was reported by the author(s).

Supplementary material

Supplemental data for this article can be accessed online at https://doi.org/10.1080/00206814.2022.2103846

Additional information

Funding

This work was supported by the Russian Science Foundation [no. 20-17-00169].