North Anatolian Fault-Saros Gulf relationships and their relevance to hydrocarbon exploration, northern Aegean Sea, Turkey

The Saros Gulf is underlain by a graben formed since Oligocene period under the influence of movements of the Anatolian and Rhodope Massifs. The oil prospectivity of this area has been enhanced by the splays of the North Anatolian Fault (SNAF) which developed later between the Anatolian and Eurasian plates during the separation of the Arabian and African plates. The interpretation of well and seismic data reveals a SW-NE graben area in the Saros Gulf. Its long axis corresponds to the thick channel deposits of the Kirazli Formation, eroded and transported from the northern Korudag High. Subsidence studies show that this graben started to form during the Oligocene and was affected by the SNAF in Miocene time. Three sedimentary and tectonic phases can be observed in the Gulf the first phase corresponds to the erosion of basement metamorphics and volcanics and the deposition of the reservoir and source rocks. The second phase is represented by the main subsidence phase, which caused the burial of the sediments in the basin. Due to the erosion of the Oligocene sediments, some abandoned channels have been formed at the northern and southern flanks of the graben area. The third phase was the establishment of the present form of the Saros Gulf under the influence of the SNAF and the divergence between the Anatolian and Rhodope Massifs. All these tectonic and sedimentary events resulted from the separation of the African and Arabian plates and collisions of the Arabian, Anatolian and Eurasian plates between Late Cretaceous (Maastrichtian) and Miocene times in Turkey. Studies of geothermal and heating gradients show that the deepest southern sector of the Saros Gulf produces gas below 3000 m, while the northern zone generates oil between 1500 and 2000 m. Evaluation of all the geological and geophysical data suggests some hydrocarbon exploration possibilities in the Saros Gulf. (C) 2000 Elsevier Science Ltd. All rights reserved.