ON SOME FEATURES OF HABITATION OF RADIOLARIANS IN THE LATE JURASSIC - EARLY CRETACEOUS BAZHENOVO BASIN OF WESTERN SIBERIA
In the article are considered the characteristic features of paleobiogeography and paleobionomy of radiolarians during the existence of the Bazhenovo marine basin in Western Siberia (late Jurassic - early Cretaceous, Volgian - Berriasian). The general paleogeography and main environ-mental factors of this paleosea, which was located inside the continent and had free communication in the north and northeast with the Paleoarctic and the Northern Pacifc oceans, are described. The area of distribution of radiolarians covered a belt of mediumhigh northern latitudes from ~ 58° to ~68°, besides radiolarians are tended to relatively deep zones of the Bazhenovo sea (more than 100-400 m). The accumulation of organic matter in the basin is due to the functioning of the eutrophic pelagic ecosystem, the central component of which was plankton, one of the important parts of which were radiolarians. The history of the development of regional radiolarian fauna in the Bazhenovo Basin of Western Siberia was complicate and included fve phases of evolution, which are correlated with radiolarian biostratons and approximately correspond to four specifc stages of sedimentogenesis. The frst mass introducing of radiolarians in the basin took place, most likely, in the Kimmeridgian, and the real development of radiolarians in this aquatory and the evolution of radiolarian fauna began during the phase 1 in the frst half of the middle Volgian (Parvicingulaantoshkinae - P. blowiZone). The fow of immigration reached its maximum in the second half of the middle Volgian during the phase 2 (Parvicingula jonesi - P. excelsaZone). The radiolarian fauna reached pike of prosperity in the end of the late Volgian and early Berriasian in the phases 3 and 4 (Parvicingula rotunda - P. alataZone and Parvicingulakhabakovi- WilliriedellumsalymicumZone). At the end of the Berriasian, there is an extinction of the fauna corresponding to the phase 5 (beds with Williriedellum), and then the radiolarian fauna ceased to exist. Radiolarians were frst-level consumers in food chains, consuming organic substances produced by primary producers: phyto- (dinophytes, prazinophytes, coccolithophorids) and bacterioplankton, and, accumulating signifcant biomass, were in trophic networks a secondary producer for higher-level consumers. The resource food base for radiolarians in the Bazhenovo basin was almost inexhaustible and the biomass produced by them was huge. The hypothesis of possible participation of biomass formed by radiolarians and deposited in the sediment in the generation of kerogen and oil is considered.