Sedimentary facies, depositional environment, and sequence stratigraphy of Oligocene–Miocene shallow water carbonate from the Rig Mountain, Zagros basin (SW Iran)

Abstract

This study investigates the depositional environment and sequence stratigraphy of the Asmari Formation that is exposed at the Rig anticline in the Izeh zone of the Zagros foreland basin with a thickness of 374 m as a sequence of thin, medium, thick, and massive carbonate rocks. The Asmari Formation is Oligocene–Early Miocene (Burdigalian) in age at the study area. In this area 12 microfacies are distinguished on the basis of their depositional texture, petrographic analysis, and fauna. These facies deposited in four major depositional environment including tidal flat, lagoon, shoal, and basin. The Asmari Formation represents sedimentation on a homoclinal carbonate ramp system. Based on the microfacies analysis, sequence stratigraphic studies, and distribution of planktonic and benthic foraminifera, six third-order sequences, three in Oligocene (Rupelian, Early Chattian, and Late Chattian in age) and three in Miocene (Early Aquitanian, Late Aquitanian, and Early Burdigalian in age), in Rig mountain section were identified.