The Carboniferous-Permian boundary and ammonoids from the Aidaralash section, southern Urals

The stratigraphic section at Aidaralash Creek, northern Kazakhstan, provides a complete and well-developed succession of strata across the Carboniferous–Permian boundary. This section, containing abundant and well-preserved ammonoid, fusulinacean, and conodont faunas, can serve well as the Carboniferous–Permian boundary stratotype. A profound change in ammonoid faunas, which occurs at the Orenburgian–Asselian boundary and which has been recognized by previous workers (e.g., Ruzhencev, 1950, 1951, 1952; Bogoslovskaya and Popov, 1986a, 1986b; Furnish, 1973; Glenister and Furnish, 1981), occurs in the Aidaralash Creek section, at the boundary between beds 19 and 20, and serves to mark the Carboniferous–Permian boundary. Additionally, Lower Permian strata at Aidaralash Creek mark the first appearance of widespread Permian ammonoid taxa, including representatives of Svetlanoceras, Juresanites, Prostacheoceras, Tabantalites, and Kargalites, that are preceded by the extinction of characteristic Late Carboniferous genera such as Prouddenites, Uddenites, Shumardites, Vidrioceras, Schistoceras, and Subkargalites.