Thrace Basin basement, comprises interbedded fine to coarse grained clastics from a variety of depositional environments, turbidite, muddy carbonates with local reef developments, river channels and tuffs. More than 400 wells were drilled till 2008; 14 gas and 3 oil fields were discovered and all of them are producing. Main gas productions zones are between Eocene- Oligocene deposits; Hamitabat (turbiditic sandstones), Ceylan (tuffs), Sogucak (reefal limestone), and Osmancik (deltaic sandstone) formations. Shales of Hamitabat and Mezardere formations have good source potentials. Thrace Basin The European side of Turkey is called the Thrace Basin. It is the largest and thickest Cenozoic sedimentary basin
Northern Thrace Bulgaria occurred here: it was 45.2 °C at Sadovo in 1916. Important rivers are the Maritsa and its tributaries. Important cities include Plovdiv, Burgas, Stara Zagora, Sliven, Haskovo, Yambol, Pazardzhik, Asenovgrad, Kardzhali, Dimitrovgrad, Kazanlak and Smolyan. Northern Thrace has an area of 42,073 km². The Ottoman Turks created the autonomous province of Eastern Rumelia in northern Thrace in 1878. The region was annexed to the Principality of Bulgaria in 1885. Northern Thrace Northern Thrace or North Thrace (, ) (as opposed to Western Thrace and East Thrace to the south) constitutes the northern and the largest part of the historical