Microfacies correlation analysis of the Oligocene-Miocene Asmari Formation, in the central part of the Rag-e-Safid anticlinal oil field, Zagros Basin, south-west Iran

Abstract

The Oligocene-Miocene Asmari Formation was deposited in a carbonate ramp setting at the margin of the Zagros Basin in south-western Iran. The subsurface sedimentary successions of the Asmari Formation have been studied using cores from the Rag-e-Safid oil field, in order to determinate their microfacies and sedimentary palaeoenvironments. Based on texture analysis and faunal assemblages, 10 microfacies types have been recognised and interpreted. They indicate different depositional settings: open marine, oolitic and bioclastic shoal, lagoon, tidal flat and beach. The microfacies have been interpreted as indicative of the inner and middle ramp. In accordance with the temporal and spatial correlation model for the Asmari Formation across the south-western part of the Zagros basin, deposition of the Asmari Formation in the south-west had started in a deeper environment and continued in a shallower high energy environment.