Mineralogy, petrography and organic geochemistry of Miocene coal seams in the Kinik coalfield (Soma Basin-Western Turkey): Insights into depositional environment and palaeovegetation

The Klink coalfield is located in the south-westernmost part of the Soma Basin in western Turkey and hosts all three Miocene coal seams (from bottom to top: kM2, kM3 and kP1). This study presents the coal-petrographical, mineralogical and organic geochemical features of samples collected from two deep cores. Samples from seam kM2 generally display low ash yields and high TOC content, whereas the kM3 and kP1 seams are characterized by relatively high ash yields and low TOC values. Furthermore, total S content of the kP1 is very high (up to 7.0%, on dry basis). The maceral composition, the coal facies diagrams, and the distributions of n-alkanes and diterpenoids indicate changes of depositional conditions and vegetation in the palaeomires of the kM2 seam during Early Miocene. The precursor peat of kM2 seam started accumulating under limnotelmatic conditions followed by pure telmatic ones. Consequently, initial mixed vegetation was replaced by a conifer-dominant assemblage in the palaeomires, in the upper parts of the kM2 seam.