First Results of U–Th/He Dating of Epigenetic Pyrite from Rocks of the Bazhenov Formation, Western Siberia

The U–Th/He method has been applied for the first time to determine the age of epigenetic pyrite from the oil source rocks of the Bazhenov Formation, Western Siberia. The possibility to date the post-sedimentation processes in a sedimentary basin by authigenic pyrite using the U–Th/He method is shown. The U–Th/He isochrone age of pyrite ( n = 7) from the dolomites of the Bazhenov Formation within the Frolovskaya megadepression is much younger than the sedimentation age and corresponds to the Santonian–Cenomanian stages of the Upper Cretaceous (90 ± 8 Ma).