Permian Ammonoids Research Papers - Academia.edu (original) (raw)
In the Tuorasis Formation section of the lower reaches of Lena River (Northern Verkhoyansk Region, Kharaulakh ridge) were first found of the goniatite Svetlanoceras, defined as S. strigosum (Ruzhencev), which had previously been known... more
In the Tuorasis Formation section of the lower reaches of Lena River (Northern Verkhoyansk Region, Kharaulakh ridge) were first found of the goniatite Svetlanoceras, defined as S. strigosum (Ruzhencev), which had previously been known only in the Southern Urals. Kharaulakh Svetlanoceras were found at the same level with numerous Bulunites mezhvilki Andrianov (the species-index of the same ammonoids Beds of the Lower Permian in the Verkhoyansk Region) and with single Eoasianites maximovae (Andrianov). The finds of S. strigosum indicates migration of the South Ural Ammonoids in the Kharaulakh subzone of the Verkhoyansk water area of Khorokytian age and suggests the Asselian age of the Khorokytian Ammonoids Asociatian, which characterizes the Bulunites mezhvilki Beds of the Khorokytian Horizon in the Verkhoyansk Region.
In the second half of the Asselian and first half of the Sakmarian the Verkhoyansk and Omolon ammonoid assemblages were formed, in which local elements (Bulunites, Kolymoglaphyrites) were dominated. Since the beginning of large Echian... more
In the second half of the Asselian and first half of the Sakmarian the Verkhoyansk and Omolon ammonoid assemblages 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 ammonoid assemblage 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 disappeared at the Late Roadian.