TRIASSIC RADIOLARIAN ZONATION IN THE FAR EAST OF RUSSIA

Abstract

In siliceous deposits of eastern Russia we can recognize, by means of radiolarians, the following biostratigraphic units: Pseudostylosphaera fragilis Beds (upper Olenekian) and zones of Hosmadia gifuensis (lower Anisian), Triassocampe diordinis (middle Anisian), Triassocampe deweveri (upper Anisian), Triassocampe scalaris (uppermost Anisian-lowermost Ladinian), Oertlispongus inaequispinosus (the lower part of the lower Ladinian), Falcispongus falciformis (the upper part of the lower Ladinian-lower part of the upper Ladinian), Muelleritortis cochleata (the middle-upper part of the upper Ladinian), Tritortis kretaensis kretaensis (lower Carnian), Capnuchosphaera theloides (upper Carnian), Capnodoce crystallina (lower-middle Norian), Lysemelas olbia (the lower part of the upper Norian), Betraccium deweveri (the upper part of the upper Norian), Livarella densipora (lower Rhaetian), and Globolaxtorum tozeri (upper Rhaetian). All zones distinguished in sections of siliceous monofacies are well correlative to those in carbonate and terrigenous sections far away. The detailed and persistent radiolarian biozonation of the Middle-Upper Triassic suggest a possibility to use this paleontological group not only for concrete stratigraphie purposes (e.g., for dating siliceous sequences), but also in a wider aspects of the global and regional Triassic stratigraphy.