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 p rospectivity of this area has been enhanced by the splays of the North Anat olian Fault (SNAF) which developed later between the Anatolian and Eurasian plates during the separation of the Arabian and African plates. The interp retation 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 Kirazl i Formation, eroded and transported from the northern Korudag High. Subside nce studies show that this graben started to form during the Oligocene and was affected by the SNAF in Miocene time. Three sedimentary and tectonic ph ases 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 p hase, which caused the burial of the sediments in the basin. Due to the ero sion of the Oligocene sediments, some abandoned channels have been formed a t 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 t he African and Arabian plates and collisions of the Arabian, Anatolian and Eurasian plates between Late Cretaceous (Maastrichtian) and Miocene times i n Turkey. Studies of geothermal and heating gradients show that the deepest southern sector of the Saros Gulf produces gas below 3000 m, while the nor thern zone generates oil between 1500 and 2000 m. Evaluation of all the geo logical and geophysical data suggests some hydrocarbon exploration possibil ities in the Saros Gulf. (C) 2000 Elsevier Science Ltd. All rights reserved .