Sedimentology and stratigraphy of the Amasra coalfield (Pennsylvanian), NW Turkey - New insight from a 1 km thick section

We report on a sedimentological and biostratigraphic evaluation that was carried out on an approximately 1 km thick coal-bearing Pennsylvanian succession encountered in the boreholes Hema 82 and 85 in the Amasra coalfield of the Zonguldak - Amasra Coal Basin, Turkey.Results of the study include a refined interpretation of sedimentary environments of the coal-bearing strata and their cyclic patterns, improved constraints on macrofloral biozones as well as of boundaries and thickness of lithostratigraphic units. A paleosol-based climatic trend is also proposed, and the tectono-sedimentary history of the Amasra coalfield is compared with other coal basins in Europe. Stratigraphically constrained macroflora confirms a recently suggested discontinuous sedimentary record that contrasts with the previously widely accepted opinion that deposition was continuous throughout the Pennsylvanian. Hiatuses were identified between each adjacent formation. An early Asturian hiatus between the Karadon and Kizilli formations has its equivalent in other Variscan basins of Europe, namely in the Dobrudzha, Upper Silesian, Intra-Sudetic and central and western Bohemian basins. It is in agreement with the former paleogeographic position of the Zonguldak - Amasra Basin and its basement in the southern margin of Laurussia, in the eastern continuation of these central European basins. This conclusion is further supported by paleosol morphology-based climatic trend to increasing aridity around the Westphalian/Stephanian boundary observed in the studied boreholes, and identical with a similar trend in the above-mentioned central European basins.