Endogenous factor of oil generation in Western Siberia

The active studies in the Western Siberia are ongoing, which are based on the new methodologies of absolute age determination using SHRIMP-II instrument, CDP seismics, and deep drilling. New well data from the depths 5000-8250 m, including those from the Gydan Peninsula, allowed updating the structural model of Western Siberia and consider the causes of the predominantly oil specialization of central areas of the geosyneclise. It is found that formation of the West Siberian Geosyneclise was accompanied by tectonic and hydrothermal activations with abnormally high uranium content in zircon up to 77 000 g/t. 29 of 100 examined wells demonstrated activations in the interval from 200 to 14.2 Ma. Phenomenon of activations has a cyclical pattern. The first cycle covers a time interval from 200 to 60 Ma; the second - from 40 to 14.2 Ma. The first cycle ends with a flash of uranium concentration up to 51,000 g/t, while the second shorter cycle ends with a 77,000 g/t pulse. There was also a general trend of shifting the activation origins from north towards south or south-south-east to the Mezhovsky area. Area of higher uranium concentration has a diameter of about 1000 km and coincides with the area of predominant oil saturation. Intermittence of activations correlates with oil column. All this shows the great role of endogenous factor (heat flows) in the formation of oil pools