Lower Palaeozoic stratigraphy and palaeontology, Karadere-Zirze area, Pontus Mountains, northern Turkey

Lower Palaeozoic rocks in the Karadere-Zirze area, east of Safranbolu (Pont ides, northern Turkey), range from Early Ordovician to Silurian. Overlying the probably Tremadoc Bakacak Formation are Aydos Formation quartzites, fol lowed conformably by the Karadere Formation, dated as Early Arenig to Early Llanvirn by means of graptolites which are assigned to seventeen genera an d include three new forms: Eoglyptograptus bouceki, Prolasiograptus haplus praecursor and Undulograptus? mui. Late Arenig trilobites from the Karadere Formation include Bergamia, Cyclopyge, Dionidella?, Leioshumardia and Sele neceme. In the Limestone Member of the overlying Ketencikdere Formation, un common trilobites suggest only a mid- to late Ordovician age, but conodonts with Colour Alteration Index 5-6 indicate the Amorphognathus tvaerensis Bi ozone (early Caradoc). Macrofossils are rare in the Siltstone Member, but c onodonts from the middle of the unit suggest the highest subzone of the A. tvaerensis Biozone; the youngest visible strata are, on acritarch evidence, at least as high as Caradoc, but the Ashgill is not confirmed and the cont act with overlying Silurian rocks is unexposed. The Findikli Formation comp rises: a Lower Member, black argillites with Llandovery graptolites and acr itarchs; and an Upper Member, grey shales with late Wenlock graptolites, ov erlain unconformably by Devonian rocks. The succession differs significantl y from contemporaneous deposits in southern Turkey and its affinities lie w ith western Europe, including the Welsh Basin.