The southeast Anatolia fold and thrust belt and its foreland basins, which has been explored for oil since the 1960's, exhibit a continuous sedimentary succession from Precambrian to Recent. Although southeast Anatolia experienced Paleozoic tectonism, the fold-thrust belt structures were formed during the Cretaceous and Miocene compressional tectonics. The belt has also been effected by the post-Miocene indentation tectonics, which formed the major strike-slip faults of the region.

The thrust belt trends approximately east-west and is divided into three major zones; complex nappes and overthrust zone (the hinterland) to the north, the frontal imbricate zone, and the foreland basins and structures to the south. We have examined many north-south and east-west trending seismic reflection profiles in the western part of the fold-thrust belt between the towns of Adiyaman and Diyarbakir. The north-south profiles extend from the frontal imbricate thrusts of the belt to the north, into the foreland structures to the south, and clearly show a Cretaceous and a Miocene detachment surface. The east-west profiles suggest that the Cretaceous folded strata were displaced by the tear faults, some of which may have been reactivated during Miocene. The Miocene detachment is structurally higher than Cretaceous detachment. In general, the Miocene thrusts have steeper ramps and larger throws than the Cretaceous thrusts. Both Cretaceous and Miocene structures have been displaced by post-Miocene strike-slip faults some of which are exposed at the surface.

The fold-thrust belt contains two main petroleum systems; the Silurian and Cretaceous. The earliest oil generation started toward the end of the Cretaceous. Therefore, the most favorable structural traps are found in the Cretaceous structures, which contain the Cretaceous carbonate rocks as reservoirs. These structures are well-developed duplexes in the footwall of the leading edge imbricates. Within the study area, duplexes have been responsible for structural traps of two recently discovered oil fields.

AAPG Search and Discovery Article #90928©1999 AAPG Annual Convention, San Antonio, Texas