Devonian-Carboniferous brachiopods and biostratigraphic findings from the Kangal Phyllite-Slate Formation (greenschist), Sivas, Turkey

Abstract

The Kangal Phyllite-Slate Formation forms the basement rocks in Kangal-Cetinkaya-Alacahan-Divrigi (Sivas). These late Paleozoic phyllite-slate associations occupy a large area, possibly composed of Early Paleozoic sediments in its lower part. The lower levels (Bakirtepe Metaquartzite Member; 0-500 m) and uppermost levels comprise the Duzce Recrystallized Limestone Member (0-25 m). The lower boundary is invisible and the upper boundary is unconformably overlain by the Kiratgedigi Limestone (late Jurassic-early Cretaceous). The studied brachiopod fauna, about 400 specimens, was collected from the 150-m-thick uppermost part of the greenschist sequences in the Kulluk Hill area, Elkondu village, 25 km east of Kangal. Some bryozoans, corals, trilobites, and crinoids were also retrieved. Five fossiliferous levels belonging to the lower, middle, and upper Devonian, and the lower Carboniferous stages were assigned as follows: (1) Pragian-Emsian; (2) Eifelian-Givetian; (3) Fransian-Famennian-Etroeungtian (Strunian); the Devonian-Carboniferus boundary; (4) lower Carboniferus: Tournaisian and Visean stages, based on the brachiopods; and (5) upper Permian: from Roadian to Capitanian stages, based on the foraminifera and algae in the Duzce recrystallized limestone. This level indicates a sedimentary interruption. All of these fossils and fossiliferous beds were correlated with the type localities and related beds. The Kangal brachiopods are similar to those of Safaktepe, the Gumusali Formations (middle and upper Devonian), and the Ziyarettepe Formation (lower Carboniferous) of the eastern Taurides. The brachiopod community is closely affiliated with the Mediterranean, northwest European Faunal Provinces, part of the Transcaucasian Region, and microfossils of the Mace recrystallized limestone belonging to the Tethyan Region. Brachiopod fauna and lithologic characteristics of the formation suggest that the upper (150 m) greenschist sequences were deposited in an open shelf environment under warm sea conditions in the Late Paleozoic era.