Microfacies and sedimentary environment of the Oligo-Miocene sequence (Asmari Formation) in Khuzestan sub- basin, Zagros Basin, southwest Iran

Abstract

The Asmari Formation is a thick carbonate succession of the Oligo-Miocene in Zagros Basin. The Oligocene-
Miocene Asmari Formation, Chidan area, is composed of limestone and calcareous marl. The Asmari Formation has
a conformable contact with the overlying (Gachsaran Formation) and the underlying (Pabdeh Formation) units and
is subdivided into three members. In order to interpret the facies and depositional environment of the Asmari
Formation, two measured sections were studied in Chidan area for microfacies analyses. In this study, eight
different microfacies types have been recognized on the petrographic studies, field observations, identification of
larger foraminifera and facies studies of the Asmari Formation (Chidan section). These carbonate microfacies
belonging to four major subenvironments: open marine (A), bar/shoal (B), lagoon (C) and tidal flat (D). The
depositional environment of the Asmari Formation is interpreted as a shallow carbonate ramp. The most of the
Asmari Formation in the study area was deposited in an inner ramp environment.