Age, microfacies and depositional environment of the Middle to Late Paleocene shallow-marine carbonates in the Sirt Basin of Libya (Upper Sabil Formation): “Are Intisar domal structures pinnacle reefs?”

Abstract In the central-eastern Sirt Basin, enigmatic Intisar domal structures host significant hydrocarbon accumulations. These have been commonly interpreted as pinnacle reefs/bioherms occurring in open-marine basinal environment. Generally, are mainly characterized by situ carbonates. The current study challenges reef/bioherm model examining one of terms biostratigraphy, microfacies and depositional were dated using larger benthic foraminifera, which yielded a Middle to Late Paleocene age (Selandian–Early Thanetian). Thirteen types representing different carbonate ramp environments ranging from outer inner ramp, defined. Outer deposits observed adjacent structure, represented wackestone with small planktonic foraminifera. most likely isochronous structures. lower part is composed foraminiferal–algal–echinodermal packstones. upper packstones intercalated microbialite–coral boundstones. euphotic preserved on crest consisting grainstone packstone rich Glomalveolina . As result this study, seen erosional relics no evidence for was found.