Al Abraq Gr

Period:

Paleogene

Age Interval:

Chattian

Province:
Cyrenaica Basin

Type Locality and Naming

According to Shaltami et al. (2020), this group consists of a lower Massah Fm separated by a major hiatus (ca. 30% of the Chattian) from the overlying Qasr Al Balatah Fm. [Neither of those formations were indicated on stratigraphic charts in other publications consulted during preparation of this lexicon.]

Synonym: Al Abraq Fm

References: Shaltami, O.R., et al. (2020), and Google Gemina (Aug’26)

Lithology and Thickness

“Characterized primarily by fossiliferous bioclastic limestones, coarse calcarenites, skeletal packstones, and marly chalky limestones. The upper portion of the group is notable for localized patchy coral reef build-ups and thick coralline red algal (rhodolith) bioclastic beds, as well as shoal-channel complex sands packed with large benthic foraminifera, bivalves, and bryozoans.” (Google Gemini overview)

Lithology Pattern:

Reef limestone

Relationships and Distribution

Lower contact

Unconformable onto the Marawah Fm of the Al Bayda Gr according to Shaltami et al. (2020). [or directly over Eocene strata, like the Darnah Formation, in uplifted areas) (Google Gemini overview).]

Upper contact

Unconformably overlain by the Al Faidiyah Fm according to Shaltami et al. (2020).

Regional extent

“Mapped across the northern Cyrenaica Basin and outcropping along the slopes and escarpments of the Al-Jabal al-Akhdar region.” (Google Gemini overview)

GeoJSON

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Fossils

Age

Chattian 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:

Chattian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

27.29

Ending stage:

Chattian

Fraction up in the ending stage:

1.0

Ending date (Ma):

23.04

Depositional setting

“Represents deposition on a open to shallow-marine carbonate ramp during a warm Oligocene sea-level highstand, before regional tectonism and minor regression marked the transition to the Al Faidiyah Fm sequence.” (Google Gemini overview)

Depositional pattern:

Additional Information

Compiler:

Shaltami, O.R., et al. (2020). Petroleum system of the Cyrenaica Basin – A review. In: 1^st 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, 32^nd International Geological Congress. 36 pp.