Revised Neoproterozoic and Terreneuvian stratigraphy of the Lena-Anabar Basin and north-western slope of the Olenek Uplift, Siberian Platform

• We revise and formalise Neoproterozoic and Terreneuvian stratigraphy of northeastern Siberia.
• Thick early to mid-Neoproterozoic succession implies protracted faulting and subsidence.
• Cryogenian (younger than 720 Ma) and lower Ediacaran deposits are missing in the area.
• Fossils can be a reliable tool in integrated chronostratigraphic studies of the Neoproterozoic.
• Fossil biota offers an important glimpse into early to mid-Neoproterozoic palaeobiology.

The early to mid-Neoproterozoic (pre-glacial) sedimentary succession of the Lena-Anabar Basin, northeast Siberian Platform, records protracted faulting and subsidence, possibly as part of the widespread continental rifting and the break-up of Rodinia. There is a significant stratigraphic unconformity separating the pre-glacial Neoproterozoic strata and the overlying upper Ediacaran succession in the Lena-Anabar Basin, with the Terreneuvian strata most likely to be deposited in a foreland of the Central Taimyr accretionary belt. The Cryogenian sensu strictum (i.e., younger than 720 Ma) and lower Ediacaran deposits are missing in the area. In this study, we assess the palaeontological content of the Precambrian and Terreneuvian strata of the Lena-Anabar Basin and the adjacent north-western slope of the Olenek Uplift and revise the chronostratigraphy of the region, with special emphasis to biostratigraphic index taxa. For the pre-glacial Neoproterozoic section, we establish the new Tukulan, Kulady, Taimylyr formations and redefine the Khastakh Formation. We also refine the Ediacaran and Terreneuvian stratigraphy by formalising the Maastakh, Khatyspyt, and Turkut formations of the Khorbusuonka Group, whereas the Kessyusa Formation is raised to group rank and subdivided into the Syhargalakh, Oppokun, Mattaia, and Chuskuna formations. The proposed stratigraphic correlation scheme is based upon depositional unity and is consistent both lithologically and biostratigraphically, providing a robust framework for future stratigraphic, sedimentological and palaeobiological studies.

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