The southern foredeep of the European-Asiatic alpine orogenic belt containing the oil fields of the Middle East is very wide and deep in its eastern and southeastern parts, but it becomes narrow and shallow in the western and northwestern parts. Lower Tertiary, Mesozoic, and, in some places, Paleozoic sediments are buried under a thick Tertiary cover in the southern and southeastern parts of the foredeep, as are the lower sections of the tectonic structures which they comprise. However, they are exposed at the surface and thus are accessible for direct investigation in the western and northwestern parts of the foredeep or, at least, are accessible for geophysical research (southeast Turkey, north Syria, northwest Iraq). Intensive geological work has been done in the Turki h Toros ranges because of the abundant copper and chromite occurrences. Thus, the features of this part of the Toros-Zagros ranges are well known today.

With these data, it is possible to reconstruct the geological history of the deep pattern of the foredeep, and also of the Toros-Zagros folding and its relation to Middle East oil fields.

The foredeep is bounded on the north by the folded zone of the Toros-Zagros belt, consisting of large overthrust bodies, the central parts of which contain Mesozoic metamorphic rocks, and a zone of local thrusts formed partly by submarine gravity slides. This zone is the southern border of the Toros-Zagros thrust region and was pushed southward over the Miocene cover of the foredeep.

The southern limit of the foredeep, in contrast, is less definite; structures and stratigraphic units of the foredeep grade gradually into those of the shield and no "borderline" can be drawn here.

Numerous tectonic features of different origin and age exist in the foredeep; remains of Hercynian and even Caledonian folds, old relief elevations caused by erosion, and fault blocks and fault zones are found adjacent to young folds. The influence of the Alpine orogenic movements originating in the Toros-Zagros belt (e.g., the widespread early Late Cretaceous, the less pronounced early Eocene, and the general late Miocene-Pliocene movements) is not the same over all the foredeep. Next to features which range from strongly or moderately affected to almost unaffected by a later movement are structures folded during one of the Alpine cycles. However, in the Tertiary cover, the existence of all these features is reflected by the presence of more or less similar domes and anticlines.

Tectonic events during the Late Cretaceous may have produced stratigraphic, lithologic, and structural oil traps in Upper Cretaceous and Tertiary rocks. Today, these trap possibilities are of economic importance for southeast Turkey, north Syria, and northwest Iraq, where occurrences of Tertiary reservoirs in the Asmari Limestone are small or non-existent. In the future these possibilities could be important in Turkey, north Syria, and northwest Iraq, as they already are in the rest of Iraq and in Iran.

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