Document Type : Original Article

Authors

1 Department of Geology, Shiraz Branch, Islamic Azad University, Shiraz, Iran

2 Department of Geology, Payame Noor University, Shiraz, Iran

Abstract

In the easternmost part of the Izeh Zone of the Zagros Mountains, the Kazhdumi Formation of upper Aptian-middle Albian age is superbly exposed in three-main outcrops showing a variety of carbonate facies. The main biogenic components of the Kazhdumi Formation are large benthic foraminifera, planktonic foraminifera and algae. The depositional system in the study area during the upper Aptian-middle Albian corresponds to a shaly carbonate ramp. Two major depositional sequences are distinguished, with an overall prograding system from west to east. Comparison of the proposed depositional sequences with those reported in the Arabian Plate and adjacent areas suggests a correlation with the global sea-level curve. The Lower Cretaceous, Aptian carbonates of Kazhdumi 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 the studied formation have higher reservoir potential and were deposited during Apt 3 and Apt 5 sequences of the Arabian Plate. The Kazhdumi Formation in the study area was deposited in an intrashelf basin that should be classified as an independent basin in the future paleogeographic maps of the southwest Iran. We interpret the Kazerun Fault, as a crustal warping of basement faults of the Arabian Plate boundary, which were responsible for the creation of the intrashelf basin in the study area.

Keywords