Palaeoenvironmental reconstruction of the Çardak coal seam, SW Turkey

•The coal-bearing Neogene sedimentary sequence in Acıgöl Basin is studied.•The lignite/subbituminous coal seam is for the first time documented.•Coal precursors were mainly herbaceous species thriving in fens.•The fens were associated with abandoned fluvial channels along with terminal lakes.

The study focuses on the firstly documented Çardak coal seam cored in the Neogene Acıgöl Basin (Denizli Province) being formed in a late stage of Alpine orogeny in SW Turkey. The aim is to contribute reconstructing the palaeoenvironmental conditions before, during and after coal formation, on the basis of coal-petrology, mineralogical and palaeontological data combined with the results of previous studies. The basin infilling consists of alluvial, fluvial and lacustrine sediments; their deposition depended on the water level in the basin, which in turn, was controlled by the interplay between tectonics and climate. Coal seam was probably formed in Latest Miocene/Early Pliocene under the influence of basin's fluvial regime in oxbow and terminal lakes. The coal seam comprises alternating inorganic and coal layers logged between depths of 599.00 to 627.00 m beneath surface. The coal being lignite to subbituminous in rank, displays moderate to high ash yield (21.31–46.11 wt.%, on dry basis) and high total sulphur content (up to 13.30 wt.%, on dry, ash-free basis). The maceral composition points to an origin from mainly herbaceous helophytes along with woody species. In the upper part of the core the presence of salinity-tolerant ostracod species along with gypsum and halite are documented. The palaeontological and mineralogical data obtained imply changes of climate, water level and lake chemistry in the basin.