Biogeographical Communications of Perm Ammonoid Communities of Verkhoyano-Okhotsky and Kolymo-Omolonsky Regions

Kutygin R.V.

 

In the second half of the Asselian and first half of the Sakmarian the Verkhoyansk and Omolon ammonoidassemblages were formed, in which local elements (Bulunites, Kolymoglaphyrites) were dominated. Since the beginning of large Echian transgression at the turn of the early and late Sakmarian almost complete taxonomic regeneration of the Ammonoids happened due to a wide expansion of the Ural elements (Uraloceras, Paragastrioceras, Andrianovia, Tabantalites) well adapted to the local environmental conditions. In the Early Artinskian the period of maximum sea warming brief invasion of the Ural biota (Neoshumardites) in the Western Verkhoyansk region took place. In the middle of the Artinskian a new ammonoidassemblage formed in the Verkhoyansk basin mostly from local elements (Eotumaroceras). The Verkhoyansk ammonoid area constantly expanded, and the assemblage transformed first to the Verkhoyansk-Okhotsk assemblage (Late Artinskian), and then to Verkhoyansk-Omolon assemblage (Kungurian – Roadian). Thus a succession of ammonoid associations took place with domination of genera of a local origin, but spread widely beyond Northeast Asia (Tumaroceras, Neouddenites, Biarmiceras, Epijuresanites, Sverdrupites). The Permian Verkhoyansk-Omolon ammonoid assemblage dissappeared at the Late Roadian.

Key words: Ammonoidea, ammonoid assemblage, areas, subareas, biogeography, Permian, Verkhoyansk region, Omolon region.

Science and Education, 2015, No.2, pp.46-50