biostratigraphy and depositional architecture of the kazhdumi formation (aptian-albian) in the izeh zone, zagros mountains, sw iran

In the easternmost part of the izeh zone of the zagros mountains, the kazhdumi formation of upper aptian-middle albian intervalis superbly exposed in three-main exposures as argillaceous carbonate facies. the main bioclastic components of the kazhdumiformation are orbitolinid and other larger benthic foraminifers, planktonic foraminifera and calcareous algae. the depositional systemin the study area during the upper aptian-middle albian corresponds to a shaly carbonate ramp. two depositional sequences aredetermined, as prograding system from west to east. comparison of the proposed depositional sequences with those reported in thearabian plate and adjacent areas suggests a correlation with the global sea-level curve. the lower cretaceous, aptian carbonates ofkazhdumi formation contain nine microfacies, which were deposited on a ramp system deepened in both directions (west and east).stratigraphic sequence led to recognize two third-order sequences. on the other hand, rudstone and boundstone lithofacies of thestudied formation have higher reservoir potential and were deposited during apt 3 and apt 5 sequences of the arabian plate. thekazhdumi formation in the study area was deposited in an intrashelf basin that should be classified as an independent basin in thefuture paleogeographic maps of the southwest iran. we interpret the kazerun fault, as a crustal warping of basement faults of thearabian plate boundary, which were responsible for the creation of the intrashelf basin in the study area.