Ordovician of North Iran: New lithostratigraphy, palaeogeography and biogeographical links with South China and the Mediterranean peri-Gondwana margin

t ains was established in 1934, when Bobek collected trilobites at Alam­Kuh (Fig. 1), which were subsequently identified by Dietrich (1937). They were only documented in more detail thirty years later, when Gansser & Huber (1962) introduced the fossiliferous Lashkarak Formation, named after its homonymous mountain. Davies et al. (1972) and Clark et al. (1975) also reported the presence of Ordovician fossiliferous strata in the Talesh Mountains, southwest of Rasht city (Fig. 1). Their Late Ordovician age was supported by a rich trilobite fauna subsequently described by Karim (2009). There was little progress in Ordovician studies for the next forty years. The information on the Ordovician and the stratigraphical ranges of the fossil content in the Alborz Mountains by Stöcklin & Setudehnia (1991), Hamedi et al. (1997) and Bruton et al. (2004) was im­ precise. Significant confusion arose after re-definition of