STRATIGRAPHY OF PALEOZOIC SHALY-SILICEOUS AND VOLCANOSEDIMENTARY DEPOSITS AND GEOLOGIC HISTORY OF THE POLAR URALS

Abstract

Conodonts found in shaly-siliceous and volcanosedimentary deposits of different tectonic zones of the Polar Urals provided a new insight into the Paleozoic history of the region. Shaly-siliceous deposits of the Central subzone of the Lemva zone (the Chernaya Gora Formation), which were attributed earlier to the Middle-Late Ordovician, are of the Middle Ordovician-Late Devonian age. The Grubeshor (the Middle Ordovician-Silurian) and Malyudshor (the Devonian) formations are distinguished in volcanogenic-siliceous deposits of the Grubeshor subzone. The Orang Formation of the Manitanyrd-Paipudyna zone, which is usually considered as Ordovician in age, should be attributed on the basis of conodont findings to the Famennian-Carboniferous. New data on the Paleozoic stratigraphy of the Polar Urals stimulated us to revise the idea that the region is a characteristic example of the passive continental margin. The Polar Urals represent a structure that developed in three destructive stages: the Late Cambrian-Tremadocian, Middle-Late Ordovician, and Late Devonian. It is inferred that a new oceanic basin, which is proposed to be named the Uralian-Arctic, emerged in the Late Devonian-Carboniferous at the junction of the East-European continent and the Middle Paleozoic accretionary system of the Urals.