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
Demographics of Turkey remain in Turkey following the 1923 population exchange, which involved the forcible resettlement of approximately 1.5 million Greeks from Anatolia and East Thrace and of half a million Turks from all of Greece except for Western Thrace. After years of persecution (e.g. the Varlık Vergisi (1942–1944) and the Istanbul Pogrom of 1955), emigration of ethnic Greeks from the Istanbul region greatly accelerated, reducing the 120,000-strong Greek minority to about 7,000 by 1978. The 2008 figures released by the Turkish Foreign Ministry places the current number of Turkish citizens of Greek descent at the 2,000–3,000 mark. According to Milliyet there are