New data on the marine Paleogene of the Southern West Siberian plate, paper 2

Age and spatial relationships between the Gan'kino, Lyulinvor, and Tavda formations, the principal subdivisions of marine Paleogene, are clarified based on comprehensive paleontological study of marine deposits, which have been recovered by two reference boreholes in the Southern West Siberian plate. As was suggested earlier, the Talitsa Formation is missed from the sequence in a greater part of the Barabinsk lithologicfacies zone. In the study area, accumulation of the Lyulinvor Formation commenced somewhat later than in central and western areas of the plate. Breaks in sedimentation are established inside and at the top of the Lyulinvor Formation below the Tavda Formation base. Sedimentation rates are evaluated, and lithological and biostratigraphic subdivisions are correlated with geological and paleogeographic events. Principal transgressive-regressive cycles and half-cycles are outlined. It is shown for the first time that accumulation of the Tavda Formation corresponded to two cycles of this kind, the second of which is represented solely by its transgressive part corresponding to Lattorfian (late Priabonian) eustatic transgression. Directions of block movements, which controlled either the basin free connection with or partial isolation from ocean, are established. Impacts of hydrology and principal Arctic and Tethyan currents on sedimentation and climate are considered.