Facies analysis and carbonate platform evolution of the Oligo-Miocene deposits in the Aghajari and Rag-e-Safid oil fields, Dezful Embayment, SW Iran

Abstract

In this study, depositional history and paleogeography of the southern margin of the Oligo-Miocene Asmari intra-shelf carbonate platform has been interpreted based on facies analysis through the north-south landward trending in the Aghajari and Rag-e-Safid oil fields. For this purpose, available data, including cores and cutting thin sections and full-set wire-line logs, from the Aghajari and Rag-e-Sefid oil fields were used. Large Benthic Foraminifera (LBF), Small Benthic Foraminifera (SBF), red algae, corals, and planktonic foraminifera are the five main skeletal components comprising the Asmari Formation. A regional time framework was established based on the latest Asmari biozonation scheme. Facies analysis led to the recognition of eight main facies (facies associations) including planktonic foraminifera, nummulitidae-lepidocyclinids, Nummulites-nummulitidae, coral-coralline red algae, small benthic foraminifera, ooid-rich facies, mudstone, and siliciclastic facies. The spatial and temporal distribution of these facies associations during the Rupelian to Burdigalian time was presented as four platform types models: a Rupelian Nummulites-Nummulitidae-dominated carbonate ramp, a Chattian Nummulitidae-Lepidocyclinidae-dominated carbonate ramp, an Aquitanian carbonate ramp, and a shallow-water Burdigalian carbonate platform.