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Compiled by: Jacques LeBlanc (2022), Stratigraphic Lexicon: The Sedimentary Formations of The Republic of Niger, Africa. Colnes Publishing (Tallin, Estonia), 365 pp. For more information see "About"

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Zarzaitine Formation

Zarzaitine Fm

Period:

Triassic

Age Interval:

Middle to Upper Triassic (Anisian to Rhaetian) (9)

Province:
Djado Basin

Type Locality and Naming

First described from the Zarzaitine field area of eastern Algeria by Lapparent & Lelubre, 1948. Part of the Continental Intercalaire.

References: Lapparent & Lelubre, 1948; Lefranc, 1958, 1991; Goudarzi, 1970; Assaf et al., 1976; Hallet, 2002, 2016; Tawadros, 2011; Shaltami et al., 2018.

Lithology and Thickness

Predominantly silty in character.

In the Zarzaitine Field in Algeria, the Formation was divided into three informal Members by Lefranc (1958, 1991): Lower unit (Adrar Ben Drich Member) of multi-colored claystone and fine-grained sandstones containing Triassic dinosaur remains; Middle unit (Zarzaitine Mbr) of mottled claystone, argillaceous limestones and dolomites, with thin bands of gypsum and anhydrite; and an Upper unit (Tekniouine Mbr) of friable, argillaceous sandstones, claystones, dolomites and gravels.
In Libya (Figure), 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. Uranium minerals were also discovered by Assaf et al. (1976) in the Zarzaitine Formation in Al Awaynat-Serdles area, Murzuq Basin, SW Libya.

Thickness: 400 m at the Type Locality. Varies from 75 to 150 m thick in southern Murzuq and Djado Basins due to erosion.

[Figure. Composite columnar section of the Zarzaitine Fm in the Tahughatin area, SW Libya. (Source: Shaltami et al., 2018).]

Lithology Pattern:

Sandy claystone

Relationships and Distribution

Lower contact

Underlying unit is the Tiguentourine Fm on the eastern side of the Djado Basin. On the western/southern sides of the Djado Basin, it may be in direct contact with the Dimbabah Fm.

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.

Regional extent

GeoJSON

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Fossils

The Formation contains abundant fresh-water shelves, calcitized fossil logs up to 5 m in length, and rare dinosaur and reptile bones.

Age

Middle to Upper Triassic (Anisian to Rhaetian) in the Murzuq Basin of Libya (Hallet, 2016, Page 86).

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:

1.0

Ending date (Ma):

201.36

Depositional setting

Continental. Includes braided-stream, alluvial plain, and lacustrine facies.

Depositional pattern:

Additional Information

Compiler:

Jacques LeBlanc (2022), Stratigraphic Lexicon: The Sedimentary Formations of The Republic of Niger, Africa. Colnes Publishing (Tallin, Estonia), 365 pp. https://doi.org/10.47909/978-9916-9760-6-7 (or via https://sites.google.com/site/leblancjacques)