New data on the upper jurassic – lower cretaceous rocks in the eastern Siberian platform

Abstract

Upper Jurassic – Lower Cretaceous boundary rocks (Laptev and Kitchan subcomplexes of the Verkhoyansk terrigenous complex) within the eastern Siberian platform and its folded framing were studied both from natural exposures in the river basins of Vilyui, Lena and Aldan and from deep horizons using samples obtained by core drilling. In the Vilyui syneclise, volcanogenic rocks were first recognized in the Upper Jurassic section of primary sedimentary terrigenous continental rocks at the boundary with the Lower Cretaceous continental terrigenous deposits. The age of the volcanogenic rocks was determined as Late Jurassic based on numerous (yet unpublished) finds of leaf flora characteristic of the Berge Formation of the Vilyui syneclise and Priverkhoyansk foredeep. In the transition zone between the Siberian platform and the Verkhoyansk-Kolyma folded region, the new section with volcanogenic rocks was correlated with the key Upper Jurassic sections of the Siberian platform on the basis of regional phytostratigraphic horizons of Siberia. The performed studies permit involvement (on equal terms) of different-facies (marine terrigenous, continental terrigenous, and sedimentary-volcanogenic rocks) info stratification of the East Siberian sedimentary paleobasin. This requires extensive use, at the western periphery of the Verkhoyansk-Kolyma folded region, of regional stratigraphic and phytostratigraphic horizons of Siberia identified and traced in the Jurassic and Cretaceous of the Verkhoyansk terrigenous complex.