The reference section of the Lower-Upper Permian boundary beds in the Verkhoyansk region and its correlation

The following Lower-Upper Permian brachiopod zonation is established in the Baraiy River basin (the western Verkhoyansk region): (1) the Megousia kuli ki Zone bearing the associated Neoudnenites-Tumaroceras yakutorum goniatite assemblage, (2) the Kolymaella ogonerensis Zone containing the Baraioceras -Tumaroceras kashirzevi ammonoid assemblage, (3) the Mongolosia russiensis Zone with the Daubichites-Sverdrupites harkeri ammonoid assemblage, (4) the Olgerdia zavodovskyi Zone, and (5) the Cancrinelloides obrutshevi Zone. Th e boundary between the Kungurian Stage of the Lower Permian and the Ufimian Stage of the Upper Permian is drawn at the base of the Kolymaella ogoneren sis Zone of the Tumara Horizon. The most distinct biostratigraphic level is the base of the Mongolosia russiensis Zone, which corresponds to the lower Roadian boundary, The compatibility analysis of Permian biotic and abiotic events in the western Verkhoyansk region shows that the Mongolosia russien sis and Cancrinelloides obrutshevi zones correspond to phases of the highes t sea level stand, which has determined ranges of the zones, The Baraiy Riv er section can be accepted for the reference one in the Verkhoyansk region. It may also facilitate correlation of the Uralian and North American stage scales.