Correlations of upper Paleozoic rocks in the Arctic have been poorly understood because of incomplete study and because faunas in different parts of this territory belong to different paleozoogeographic regions. The Tropical paleozoogeographic region is characterized by the abundance and variety of faunas, and the Boreal region is characterized by faunal impoverishment. The areal extent of the Boreal environment was smallest in the Middle Carboniferous; it gradually spread throughout the Arctic by Late Permian time.

In the Tropical region, the Bashkirian and Moscovian Stages of the Middle Carboniferous are clearly distinguished on the basis of fusulinids and brachiopods. The writers consider the Upper Carboniferous as a single stage (Gzhelian). In the Boreal region, we assign to the Bashkirian Stage deposits containing a brachiopod complex best represented in Taymyr. This section was originally assigned to the Lower Permian. The Moscovian Stage is distinguished by a fauna differing significantly from the Bashkirian fauna. Upper Carboniferous deposits are difficult to distinguish in the Boreal region, because of their sparse atypical fauna.

The Carboniferous-Permian boundary in the Tropical region is thought to be at the base of the Asselian Stage. The boundary in the Boreal region is currently determined by the appearance of characteristic brachiopods, but the true boundary is probably at a lower level.

The writers distinguish two Lower Permian stages. The Asselian Stage corresponds to the Schwagerina Horizon, and the Artinskian Stage includes the Sakmarian, Artinskian, and Kungurian Stages of the Urals and the Russian platform.

The Lower-Upper Permian boundary is debatable. The writers define this boundary in the Boreal region by faunal development associated with a general sea transgression. The boundary thus drawn approximates the base of the Ufimian and the Lower-Upper Permian boundary of the Tethys.

Within the Upper Permian the writers accept the Paykhoyan and Kazanian Stages. The Paykhoyan Stage is well established in the Boreal region by typical brachiopod and pelecypod complexes. We consider the Kazanian Stage to include the Kazanian and Tatarian Stages of the Russian platform. In continuous marine sections, no faunal change that would allow distinguishing of the two stages is found.