Dahra Formation

Dahra Fm

Period:

Paleogene

Age Interval:

Paleocene (Selandian).

Province:
Sirte Basin

Type Locality and Naming

Synonym:

References: Ahlbrandt, 2001; Abugares, 2007

Lithology and Thickness

The Dahra Fm. is made up of shales that laterally transition into limestones (Fig. 7 of Ahlbrandt, 2001). It consists mainly of white to light grey chalky, calcarenite, calcilutite and subordinate tan to brown microcrystalline dolomite and thin interbeds of dark shale with minor anhydrite in the ·upper part of the formation. In the southwestern part of the basin. the lower part of the formation. becomes more shale. (Abugares, 2007).

Lithology Pattern:

Clayey limestone

Relationships and Distribution

Lower contact

It conformably overlies the Radia Shale Member of the Beda Fm.

Upper contact

It is conformably overlain by the Khalifa Fm; although it is partly the lateral equivalent of the lower shale units of that Khalifa Fm.

Regional extent

GeoJSON

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Fossils

Age

Schematic stratigraphic column of Ahlbrant (2001) places as either lower Selandian (used here for graphic purposes) or upper Selandian.

Age Span:

Beginning stage:

Selandian

Fraction up in beginning stage:

0.00

Beginning date (Ma):

61.66

Ending stage:

Selandian

Fraction up in the ending stage:

0.5

Ending date (Ma):

60.45

Depositional setting

The formation was deposited during gradual shallowing of the sea (El Kanouni, 2014).

Depositional pattern:

Additional Information

Compiler:

T. S. Ahlbrandt (2001): The Sirte Basin Province of Libya—Sirte-Zelten Total Petroleum System, U.S. Geological Survey Bulletin 2202–F

R.C. Selley (1997): The Sirte Basin of Libya. In: African Basins. Sedimentary Basins of the World, 3, edited by R.C. Selley (Series Editor: K.J. Hsu), Elsevier Science B.V., Amsterdam, pp. 27-37.

Abugares, Miloud M. (2007): Deposition, Diagenesis, and Reservoir Development of the Cretaceous Lidam Formation, SE Sirt Basin, Libya. Durham e-Theses. http://etheses.dur.ac.uk/2599/

Elkanouni, I. E. D. (2014). Sedimentology, Sequence stratigraphy and Spatial-temporal Patterns of the late Paleocene Succession, western Sirt Basin, Libya, Durham e Theses. http://etheses.dur.ac.uk/10538/