The Position of the Wuchiapingian–Changhsingian Boundary in Northeast Russia on the Basis of Radioisotopic and Chemostratigraphic Data

Abstract

Abstract: The approximate position of the Wuchiapingian–Changhsingian boundary of the Upper Permian in Northeast Russia was determined for the first time on the basis of the comparison of δ13С trends established in the sections of South China and Iran, the Tethyan Superrealm, and the Pautovaya River section (Kolyma–Omolon region, Boreal Superrealm). This boundary runs in the middle part of the Intomodesma costatum bivalve zone of the Khivachian regional horizon. This conclusion is also confirmed by the previous dating of zircons from a tuff layer below the Wuchiapingian–Changhsingian boundary in the same section and by 87Sr/86Sr values from well-preserved brachiopod-spiriferid shells from the stratotypical section of the upper part of the Khivachian regional horizon on the Omolon massif.