Biostratigraphical implication of Middle–Upper Cambrian acritarchs from Severnaya Zemlya (high Arctic of Russia)

Lower Paleozoic organic-walled microfossils from the October Revolution Island (Severnaya Zemlya Archipelago) have been investigated taxonomically and biostratigraphically. Four acritarch assemblages allow a stratigraphical correlation of the studied strata with Baltic trilobite zonations from the Paradoxides paradoxissimus trilobite Zone of the Middle Cambrian to the Peltura minor trilobite Zone of the Upper Cambrian. The fifth assemblage is poor and contains neither typical Cambrian taxa, nor Ordovician species of definite biostratigraphical value. The uppermost Cambrian interval embracing at least two trilobite zones (Peltura scarabaeoides and Acerocare) has not been recognized in the Cambrian–Ordovician succession of the October Revolution Island.