2021/04/20 by Adrian W. A. Rushton, Adrian W.A. Rushton, Mansoureh Ghobadi Pour +3 · 7 citations
Earth and Planetary Sciences · #Biostratigraphy #Biozone #Ecological succession #Ecology #Geological formations and processes #Geology #Geology and Paleoclimatology Research #Group (periodic table) #Ordovician #Paleontology #Paleontology and Stratigraphy of Fossils #Structural basin #Unconformity
paper · doi:10.1017/s0016756821000273
published in Geological Magazine 158(10), 1719-1732 (Cambridge University Press)
openalex publication_date 2021/04/20 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/25
Abstract Graptolites have been collected from sections through Lower Ordovician strata in northern Iran. At the Saluk Mountains, in the Kopet–Dagh region, mudrocks yielded fragmentary tubaria of Rhabdinopora sp. cf. R. flabelliformis , indicating the presence of lower Tremadocian strata there; stratigraphically, they lie between two limestone beds with the euconodont Cordylodus lindstromi . At Simeh–Kuh in the eastern Alborz Mountains (Semnan Province), upper Tremadocian – lower Floian strata include laminated dark mudstones that contain restricted graptolite faunas, mainly of small declined didymograptids; these are thought to represent incursions of plankton during periods of marine highstands. The lower major flooding surface in Simeh–Kuh coincides with an invasion of the graptolite biofacies and an incursion of Hunnegraptus ? sp.; the second major flooding surface is associated with an incursion of Baltograptus geometricus . They were most probably synchronous with those in the lower part of the Hunnegraptus copiosus Biozone and at the base of the Cymatograptus protobalticus Biozone in the of the Tøyen Shale Formation succession of Västergötland, Scandinavia, suggesting that observed characters of sedimentation were eustatically controlled.