Stratigraphy, diversity and palaeobiogeography of the Upper Visean (Lower Carboniferous) rugose corals from northwestern Turkey

In northwestern Turkey, the Visean part of the Yilanli Formation is dominated by shallowwater limestones containing rugose corals, tabulate corals and brachiopods. In the Zonguldak and Bartm areas based on six sections two assemblages are recognized The lower one includes numerous lithostrotionids (Siphonodendron martini, S. irregulare, S. pauciradiale, S. asiaticum, S. scaleberense, S. kleffense, and Lithostrotion araneum) associated with the solitary rugose corals Palaeosmilia murchisoni, Clisiophyllum keyserlingi, Aulophyllum fungites, Siphonophyllia siblyi and Koninckophyllum interruptum. This first assemblage is typical of the lower Warnantian RC7 beta rugose coral zone of Western Europe and is dominated by taxa with a wide spatial distribution within the Western European province. This assemblage is common both in the Bartm and Zonguldak areas. The second assemblage is known in Zonguldak, but not in Bartm, where the upper part of the Yilanli Formation is lacking. This assemblage is composed of are the colonial species Siphonodendron martini, S. irregulare, S. pauciradiale, S. asiaticum, S. scaleberense, S. rallii, Lithostrotion decipiens, Palastraea konincki , Corwenia cf. vaga, Nemistium cf. affine and the solitary species Aulophyllum fungites, Palaeosmilia murchisoni, Axoclisia cf. cuspifonna and Pseudozaphrentoides cf. juddi. Palastraea, Corwenia and Nemistium are the guide taxa of the upper Warnantian RC8 biozone. The palaeobiogeographic affinity of these two assemblages is clearly European and they are similar to the Upper Visean coral fauna of Belgium and England. Only S. asiaticum indicates a greater Asian influence making it similar to the Donets Basin. The absence of the genera Diphyphyllum, Dibunophyllum, Axophyllum, Gangamophyllum and Lonsdaleia is a singularity of the Zonguldak and Bartm area and is not explained by any facies issue so far.