The West-Siberian Triassic sediments are analyzed with the emphasis given to their composition and stratigraphic subdivision based on large-size remains of fauna, flora and microfossils. Triassic sediments penetrated by deep boreholes contain bivalve shells, spores and pollen. A specific palynocomplex is found in the sediments, allowing recognition of the Olenek Stage. Because of the great number of acritarchs (one of the dominant of the stage) the sedimentation supposedly occurred in comparatively large saline-water basin. New data on the stratigraphy of new Triassic sections are important for detecting the geological structure of the West-Siberian pre-Jurassic complexes and for assessment of their oil and gas potential.
