Southeast Turkey is tectonically divided into several zones. These tectonic zones present slightly different stratigraphic rock units. The main difference is the presence of the Kosali and Karadut complexes, allochthonous units that came into the environment as a result of gravity sliding. The Kastel basin, formed by of subduction of the Arabian plate, was the site for the allochthonous units to slide in. Faulting and associating folding took place farther south and provided traps for hydrocarbon accumulation.
The Cretaceous Mardin group consists of several formations, including the source and reservoir rocks of the area. Based on the screening geochemical analysis of source rock samples from a large number of wells, and detailed geochemical and biomarker analyses from some selected wells, a basin analysis study of some wells was made. Results showed that the presence of allochthonous units affects the area mainly in two aspects: (1) the placement of the allochthonous units caused faulting and associated folding to provide potential traps for early hydrocarbon accumulations, and (2) as a result of deep burial by the allochthonous units, early maturation and generation of oil took place. In the areas where there are no allochthonous units in the stratigraphic record, maturation of the source rock and oil generation are quite late and in some cases not sufficient for an entrapment.
Although Miocene structures are bigger, they are generally dry because of the early generation and entrapment of oil.
AAPG Search and Discovery Article #91003©1990 AAPG Annual Convention, San Francisco, California, June 3-6, 1990