oligocene stratigraphy of the northern subcoastal fars zone (tang-e-khoshk, zagros structures, iran): biostratigraphy and paleoenvironment

objective: the asmari formation is characterised by alternation thick carbonate and marl sequence of the oligocene- miocene in the zagros basin, southwest of iran that were deposited on the shelf of eastern paratethys. methods: this formation is exposed at tang-e-khoshk in the fars subcoastal zone with a thickness of 286 m comprising alternation of medium and thick to massive bedded carbonates, marlylimestone and marl. the age of the asmari formation in the study area is the oligocene (ruplian&chattian). results: ten microfacies are defined, characterizing a gradual shallowing upward trend; the related environments are as follows: open marine (mf1, 2&3), shoal (mf4) and lagoon (mf5, 6&7). a carbonate ramp platform is suggested for the depositional environment of the asmari formation. mf 1, 2, 3 &4 are characterized by the occurrence of large and small foraminifera representing a represent a deeper fair weather wave base of a middle ramp setting. mf 5, 6& 7 with large particles of different bioclast debis and algae, shallow-water setting of an inner ramp.