Dev-F6 Formation

Dev-F6 Fm

Period:

Silurian – Devonian

Age Interval:

Pridoli – Pragian.

Province:
Illizi Basin

Type Locality and Naming

Synonym: Laterally equivalent to the Acacus and Tadrart formations in the Ghadames and Al-Khufrah basins (Benvegnù, 2020)

References: Benvegnù, 2020

Lithology and Thickness

The lower part, which is laterally equivalent to the Akakus Fm. of the Ghadames Basin, consists of shelf-coastal/deltaic sandstones and mudstone deposited during the subsequent regression. The top of this basal layer is ferruginous and contains plant remains, thus interpreted to be a continental deposit (Benvegnù, 2020). The upper part, which is equivalent to the Tadrart Fm. of the Ghadames Basin, is made up of a lowstand system characterized by continental fluvial medium to coarse sandstones and mudstones. The sheet sands are cut by sand filled-channels with a good porosity (Benvegnù, 2020).

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

It conformably overlies the Argileux Fm.

Upper contact

It is conformably overlain by the F4-5 Fm.

Regional extent

Illize Basin of SE Algeria

GeoJSON

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Fossils

Age

Age Span:

Beginning stage:

Pridoli

Fraction up in beginning stage:

0.00

Beginning date (Ma):

422.73

Ending stage:

Pragian

Fraction up in the ending stage:

1.0

Ending date (Ma):

410.51

Depositional setting

Coastal/deltaic – continental (Benvegnù, 2020).

Depositional pattern:

Additional Information

Compiler:

Enam O. Obiosio, Solomon Joshua Avong and Henry Nasir Suleiman (2024) - Stratigraphic Lexicon compiled from the following books:

Benvegnù I. (2020): Thermal Evolution of Paleozoic and Triassic Reservoir Rocks in the Ghadames-Illizi Basin (Algeria). An unpublished MSc thesis at Universita’ degli Studi di Padova.

T.R. Klett (2000): Province, Algeria, Tunisia, and Libya - The Tanezzuft-Oued Mya, Tanezzuft-Melrhir, and Tanezzuft-Ghadames. U.S. Geological Survey Bulletin, 2202-C.