Upper Cambrian–Lower Ordovician conodonts from the southern margin of the Kopet-Dagh Basin, Saluk Mountains, Iran

Abstract

A detailed Furongian to Tremadocian conodont biostratigraphy is established from the Saluk Mountains located in southern Kopet-Dagh, northeast Iran. Thirty species assigned to 17 genera were recovered from decimetre-scale limestone beds in a fine-grained siliciclastic succession, deposited in an intraplate rift system. The following biozones are established for the region, in ascending order: Proconodontus muelleri, Eoconodontus, Cordylodus intermedius, Cordylodus lindstromi, Cordylodus angulatus, Paltodus deltifer and Acodus triangularis interval zone. This low-to medium-richness conodont fauna comprises cosmopolitan euconodont species of Proconodontus, Eoconodontus, Cordylodus, Teridontus nakamurai, Semiacontiodus nogamii and a few long- ranging proto- and paraconodont species, which inhabited a narrow marine basin flanked by landmasses and formed by active rifting. It lacks shallow water tropical taxa and probably belongs to the Cold Domain of the Shallow Sea Realm. The occurrence of conodonts of the Paltodus deltifer Biozone in the uppermost part of the Qyzlar Formation in the Ghelli section suggests that the major episode of flood basalt volcanism in south Kopet-Dagh commenced in the late Tremadocian. Hadi Jahangir [Jahangir.hadi@nigpas.ac.cn] and Guanzhou Yan [gzyan@nigpas.ac.cn], State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing 210008, PR China.