Geology of Northeastern Russia
The geology of Northeastern Russia is extremely complex. Numerous microcontinental terranes with mainly passive margins accreted over time (see below) resulting in numerous depositional basins. By the early Mesozoic the Eastern Siberian continent (Siberian Platform), the Chukotsk and Bureinsk-Khankaisk microcontinental terranes and the inferred Okhotomorsk terrane. By the end of the Neocomian the continental margin of NE Asaia had assumed a geometry similar to that of present and was separated from the Pacific Ocean by Andean-type active continental margins marked by the Okhotsk-Chokotka and Sikhote-Alinsk volcanogenic belts. Strike-slip faults within the Sikhote-Alinsk area developed sub-longitudinally during the Cretaceous after the attachment of the Bureinsk microcontinental plate to the Siberian platform and were related to the northward movement of the Okhotomorsk microcontinental terrane towards the Okhotsk-Chokotka volcanogenic belt.
|Fold belts of Northeastern Russia based on Perfenov and Natalin, 1986. Microcontinental sialic terrains are as follows: Bu - Bureinsk, Kh - Khankaisk, Ok - Okhotsk, Okm - Okhotomorsk, Om - Omolonsk.|
For the purposes of this catalogue we recognise three distinct geological subregions: The Verkhoyansk-Chukotka Subregion (VCSR), The Okhotsk-Chukotka Subregion (OCSR), and the Anadyr-Koryak Subregon (AKSR). The Verkhoyansk-Chukotka subregion encompasses part of the Siberian Platform and the Verkhoiano Chukotsk region shown above, while the latest Cretaceous fold belts in the map above form the OCSR.
A major feature of Northeastern Russia, and one that is highly significant from the perspective of preserving a record of the Late Cretaceous Arctic biota is the Okhotsk-Chukotka Volcanogenic Belt indicated by 'V' ornamentation on the map to the right.
Right: Map of NE Russia showing the three gelogical subregions used in this catalogue.