There are several different theories for the mechanism of development of pre-Jurassic sequences in Western Siberia. Many geologists believe that Hercynian-Caledonian and Bayikalian orogenies of the Paleozoic age affected all pre-Jurassic deposits. Others assume that pre-Jurassic-Paleozoic sediments were formed in the Paleo-Asian ocean that existed in Western Siberia. The model proposed by the writers is based on the analysis of the latest seismic data combined with the interpretation of geologic and other geophysical data, thereby allowing a reevaluation of both the new model and its more widely accepted predecessor. A new model concerning the geologic structure of pre-Jurassic deposits in the southeastern part of Western Siberia is proposed by the writers. It is based on the crucial identification of pre-Jurassic-Triassic Paleozoic sediments in the pre-Jurassic rift zones. Validation of such a model would prove to be crucial in that oil and gas plays of the southeastern part of Western Siberia are known to be associated with the pre-Jurassic synrift sequences.