Darnah Fm
Period:
Paleogene
Age Interval:
Bartonian
Province:
Cyrenaica Basin
Type Locality and Naming
Synonym: Dernah Fm
References: Shaltami, O.R., et al. (2020), and Google Gemina (Aug’26)
Lithology and Thickness
Cherty, fine-grained globigerinal and nummulitic limestone and marly carbonates deposited in deep shelf environments.
Lithology Pattern:
Clayey limestone
Relationships and Distribution
Lower contact
Unconformable onto the Apollonia Fm according to Shaltami et al. (2020).
Upper contact
Unconformably overlain by the Salantah Fm according to Shaltami et al. (2020).
Regional extent
GeoJSON
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Fossils
Age
Bartonian according to Shaltami et al. (2020). [For graphic purposes, the extent of the upper and lower unconformities, which are equivalent to nearly the same time span of the known preserved deposits, have been omitted here.]
Age Span:
Beginning stage:
Bartonian
Fraction up in beginning stage:
0.0
Beginning date (Ma):
41.03
Ending stage:
Bartonian
Fraction up in the ending stage:
1.0
Ending date (Ma):
37.71
Depositional setting
Depositional pattern:
Additional Information
: “Historical Naming Dispute: In traditional regional mapping (e.g., Pietersz, 1968), the Eocene succession was divided into three formal units: Apollonia Fm (late-Early Eocene), Darnah Fm (Middle Eocene), and Salantah Fm (Late Eocene). Later mapping campaigns merged the Salantah Fm into the upper portion of the Darnah Fm. Modern high-resolution biostratigraphy and strontium isotope geochronology have reinstated the distinction, identifying a clear depositional break (missing Middle Priabonian strata) that justifies keeping the Salantah Fm as a stand-alone unit above the Darnah Fm.” (Google Gemini overview)
Compiler:
s:Shaltami, O.R., et al. (2020). Petroleum system of the Cyrenaica Basin – A review. In: 1st International Symposium on Geosciences (ISG2020), 21th March 2020, Proceeding Book: published by BR Petrobras. P. 64-71.Tawadros, E.E. (2011). Geology of North Africa. CRC Press (Taylor & Francis Group), 931 pp.Google Gemini (Aug 2026) – assembled synthesis of Cyrenaica Basin units from various web-accessible publications.
El Oshebi, F.M., Fares, F.F. (2026). Stratigraphy, facies, and depositional environments of the Eocene sequence in the Ras Al Hilal area, Cyrenaica, Libya. Arabian Jour. Geosciences, 19:79. https://doi.org/10.1007/s12517-026-12488-2.
El-Hawat, A.S., Abdulsamad, E.O. (2004) Geology and Archeology of Cyrenaica, Northeastern Libya. Field trip guide B01, 32nd International Geological Congress. 36 pp.