JURASSIC RADIOLARIANS FROM NORTHERN RUSSIA

Abstract

The latitudinal models of radiolarian paleogeographic provinces are considered, and Late Jurassic boreal radiolarian assemblages of Russia are characterized. Several Jurassic radiolarian assemblages from the Koryak Upland are correlated with the Boreal-Atlantic, Arcto-Boreal, and Tethyan assemblages of these organisms. The presented paleontological description is devoted to characteristic radiolarian species from the Pechora basin and Koryak Upland. Species occurring in both regions are Parvicingula blowi, P. blackhornensis, P. burnsensis, P. elegans, and P. enormis. The former conclusion that the Bathonian-Callovian and Kimmeridgian-Tithonian radiolarians from some tectonic sheets of the Koryak Upland (the Talovka River, Rarytkin Ridge, and the left-hand side of the Utesiki River) are of the North Tethyan type is found to be correct. The established proportions between parvicingulids, pantanelliids, and other radiolarian groups suggest that most of Late Jurassic radiolarian assemblages from the Kuyul terrane originated near the boundary between the southern and northern Tethyan provinces, whereas coeval radiolarian communities from the Rarytkin Ridge can be considered as subboreal, dwelled close to the frontal zone of southern Boreal provinces.