The sedimentologic characteristics of coal-bearing Oligo-Miocene deposits occurring at the north of İstanbul have been examined in this study. The study area in Thrace Basin includes coal formations in deltaic deposits of Oligo-Miocene age. Coal-bearing deltaic deposits in this field have been evaluated in the Danişmen formation and the coal bed has been extensively exploited by open-cast methods.
The Danişmen Formation overlies the Eocene-Oligocene Ceylan Formation unconformably and consists of mudstone, sandstone, conglomerate and coal. It is unconformably overlain by the Pliocene deposits. Coal-bearing succession is composed of fining-upward interbedded facies. Five facies were identified in Coal-bearing sediments. These facies are; bedded conglomerates, thick bedded sandstones, organic rich grey mudstones, red mudstone and coal. These facies characterize delta plain deposits. The coal of the Danişmen Formation was deposited in swamps of delta plain. The coal bed in the Danişmen Formation has a thickness of 7.80 m, and the coal rank is of a lignite stage (soft brown coal).