The sedimentary sequence of the south Thrace Basin (northwest Turkey) comprises Upper Cretaceous-Holocene sediments. In this basin, the Korudag anticlinorium, which is the subject of this study, is located between the Aegean Sea in the west and the Sea of Marmara to the east. The anticlinorium, which is approximately 300 km (186 mi) long and 40 km (25 mi) wide, was formed by effects of the Neotethys subduction-accretion complex and Istranca massif collision during the late early Miocene. The Korudag anticlinorium was deformed to its present-day structure by the oldest splay of the North Anatolian fault (upper middle Miocene) and branch of the North Anatolian fault (NAF-N) (not earlier than 200 ka). Organic geochemical analysis, oil and gas to source rock correlation, and basin modeling studies suggest that the Korudag anticlinorium should be charged by hydrocarbons generated from the Karaagac, Ceylan (regionally), and Mezardere formations. Gas and oil are being produced from the Korudag anticlinorium and its subparallel anticlines in the north Marmara, Degirmenkoy, Seymen, Cayirdere, Karacali, Yulafli, Tekirdag, Sevindik, and Vakiflar (gas plus oil) fields. Mapping done as part of this study indicates that the Korudag anticlinorium has not yet been tested and explored comprehensively.