Zarzaitine Formation

Zarzaitine Fm

Period:

Triassic

Age Interval:

Anisian - Carnian

Province:
Murzuq Basin

Type Locality and Naming

First described from the Zarzaitine field area of eastern Algeria by Lapparent & Lelubre, 1948. This formation was introduced by Burollet (1960). It outcrops in the west of the NC-115 area (Alkhalas, 2006).

Synonym:

References: Aziz, 2000; Alkhalas, 2006

Lithology and Thickness

the formation was divided into three informal members: a lower unit of multi-colored claystones and fine-grained sandstones, a middle unit of mottled claystones, clayey limestones and dolomites, with thin bands of gypsum and anhydrite, and an upper unit of friable, clayey sandstones, claystones, dolomites and gravels. The total thickness is about 400m (Aziz, 2000; Alkhalas, 2006). In Libya, it is composed of alternating bands of gypsiferous and ferruginous claystone, dolomitic marls, micaceous siltstones, and quartzose sandstones and gravels, with a distinctive brown color. The threefold division was not adopted. Thickness: 400 m at the Type Locality. Varies from 75 to 150 m thick in southern Murzuq and Djado Basins due to erosion.

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

It unconformably overlies the Dembaba Fm (Hercynian unconformity - Aziz, 2000).

Upper contact

“Top is an erosional contact marked by a lateritic horizon, 3-4 m thick, indicating an important sedimentation break before the deposition of the overlying Taouratine Fm.” (J. LeBlanc, see Nigerlex.geolex.org)

Regional extent

GeoJSON

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Fossils

Contains dinosaur and vertebrate remains. Famous for yielding early Mesozoic vertebrate fossils, including temnospondyl amphibians ("stegocephalians") and dinosaur/reptile-associated remains in its lower variegated clay and sandstone beds.

Age

traditionally mapped as a Middle-to-Upper Triassic. Used the Anisian-Rhaetian age span of Stratigraphic Lexicon: The Sedimentary Formations of The Republic of Niger, Africa. By Jacques LeBlanc (2022) (see Nigerlex.geolex.org), which referenced Hallet, 2016, page 86. A break of late-Rhaetian is assumed here for the top unconformity.

Age Span:

Beginning stage:

Anisian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

246.70

Ending stage:

Rhaetian

Fraction up in the ending stage:

0.5

Ending date (Ma):

203.55

Depositional setting

Deposited under hot, dry continental conditions by a network of shifting rivers and temporary lakes.

Depositional pattern:

Additional Information

Hosts significant strata-bound, sandstone-type uranium mineralizations (such as beta-uranophane and carnotite) notably studied around the Al Awaynat and Tahughatin areas in southwest Libya.

Compiler:

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

Jacques LeBlanc (2022) Stratigraphic Lexicon: The Sedimentary Formations of The Republic of Niger, Africa. Colnes Publishing (Tallin, Estonia), 365 pp. (freely available on ResearchGate)