On the Composition and Age of Taphofloras of the Krivorechenskaya Formation (Upper Cretaceous) of the Anadyr River Left Bank, Northeast Asia

Chineiveem taphoflora from the Krivorechenskaya Formation of the Anadyr River left bank (Northeast Asia) is characterized by a relatively low diversity of plants represented by ginkgoaleans, conifers, and angiosperms. Judging by their systematic composition, this taphoflora is younger than the Grebenka flora from the Krivorechenskaya Formation of the Anadyr River basin. Its closest analog is the Penzhina flora of Northwestern Kamchatka and the Yelistratov Peninsula, the age of which is reliably defined as Turonian, excluding the beginning of the Turonian. Therefore, the age of the Chineiveem floristic assemblage is also Turonian, most probably late Turonian. Such dating of this taphoflora is in agreement with the late Turonian or Coniacian age of marine mollusks from the overlying Dugovskaya Formation layers of the Chineiveem River and with a conformable stratigraphic contact of these layers with the plant-bearing beds. A tectonic contact between these deposits is not supported by our paleobotanical data. The observed succession of taphofloras from the Krivorechenskaya Formation in the Ubiyenka–Chineiveem interfluve suggests that the upper age limit of the Grebenka flora is the beginning of the Turonian.