Relations between Deep and Shallow Stratigraphic Units of Northern Iraq during Cretaceous

The study area includes Sulaimani, Erbil and Dohuk Governorates where Cretaceous rocks are well exposed in the High Folded Zone of North and Northeastern Iraq. This area is part of the northwestern boundary of the Arabian platform near the Iranian border. In these governorates, the study tries to clarify the relationship between deep and shallow stratigraphic units (formation or facies) during the Cretaceous period. The results of the present study are mainly dependant on the field lateral tracing of the lithologic changes and paleontological evidence for indicating the new age termination of the units. The results showen are a generalized and simple model of temporal and special relations between Cretaceous deep and shallow water formations. The Balambo (Kazhdumi in Iran), Kometan (Ilam), Shiranish-Tanjero (Gurpi) Formations (as deep facies) are indicated as lateral equivalents of shallow facies of Qamchuqa (Sarvak and Dariyian), Bekhme (has no equivalent in Iran yet) and Aqra Formation (Seymare or Tarbur) respectively. On the model, the transition zone is indicated where the deep facies, from the southeast, change to shallow ones in the northwest. The shallow facies consist of coarse grain limestone with fossils, skeletons, bioclasts and intraclasts. The deep facieses are fine grain pelagic limestone with microfossils (panktonic forams and nanofossils) whiles the transitional facies (zones) generally consist of a mixture of the two as interfigering relation between the deep and shallow facies. As the changes of the lithology of transitional zones are relatively sudden, they are not designated as formations and not defined previously.