ABSTRACT: Six stratigraphic sections were investigated from the middle Eocene to middle Miocene carbonate deposits along the Tobruk-Al Bardia scarps of northeastern Cyrenaica, NE Libya. The studied sequence comprises five rock units; the Darnah, Al Bayda, Al Abraq, Al Faidiyah, and Al Jaghbub formations. Eleven carbonate facies were distinguished at outcrop-scale and several microfacies were recognized and the outcome indicates a shelf-carbonate platform complex. The palaeohabitat of larger benthic foraminifera and associated biota in the studied sequence has been interpreted by comparison with its present-day counterpart. Nine shallow benthic foraminiferal biozones are recognized based on first and last occurrences of diagnostic larger benthic foraminifera. The late middle Eocene Darnah Formation contains a nummulitic assemblage with variable species, including the Nummulites gizehensis/Nummulites lyelli group, which represents SBZ17-SBZ18 in the Bartonian. The recovery of Nummulites vascus and Nummulites fichteli and associated taxa ascribes the overlying deposits of the Al Bayda Formation to the early Oligocene (early Rupelian) larger foraminiferal zone SBZ21. The total nummulitid assemblage of the overlying Al Abraq Formation is early Oligocene (late Rupelian) in age which corresponds to larger benthic foraminiferal zone SBZ22. The base of the zone correlates with the base of the Al Abraq Formation and is defined by the first appearance of Operculina complanata and Eulepidina cf. dilatata. The top of the zone is present in the lower part of the Al Faidiyah Formation (early Chattian) and is marked by the first appearance of Miogypsinoides complanatus. The middle part of the formation corresponds to larger foraminiferal zone SBZ23 (late Chattian). The base of this zone is marked by Miogypsinoides complanatus whereas the top of the zone is marked by last occurrence of Eulepidina cf. dilatata and Nephrolepidina sp. and the first appearance of Nephrolepidina aff. tournoueri. The upper stratigraphic levels of the Al Faidiyah Formation correspond to larger foraminiferal zone SBZ24 in the lower Miocene (Aquitanian). The base of the zone is marked by the first occurrence of Nephrolepidina aff. tournoueri and the upper zone boundary is represented by the last occurrence of the latter taxa and the first appearance of Miogypsina globulina. The last two larger benthic foraminifera zones which have been recognized in the deposits of the overlying Al Jaghbub Formation represent zones SBZ25 in the Burdigalian (early Miocene) and SBZ26 in the Langhian and Serravallian (middle Miocene). The base of zone SBZ25 is marked by the last occurrences of Miogypsinoides complanatus and Nephrolepidina aff. tournoueri and the first appearance of Miogypsina globulina. The top of SBZ25 and the base of the upper SBZ26, however, is marked by the last occurrence of the latter taxa and the first appearance of Borelis melo melo.
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