Zarzaitine Inferieur Formation

Zarzaitine Inferieur Fm

Period:

Triassic.

Age Interval:

Carnian – Rhaetian.

Province:
Illizi Basin

Type Locality and Naming

Synonym: Lower Zarzaitine Fm

References: Klett, 2000; Benvegnù, 2020.

Lithology and Thickness

The basal unit, which is laterally equivalent to the TAGI Fm of the Triassic (or Oued Mya) Basin, is characterized by quartz-arenite that grades into sub-arkosic sandstones with excellent reservoir properties (Klett, 2000; Benvegnù, 2020). The midsection, which is the lateral equivalent of the TAC Fm of the Triassic (or Oued Mya) Basin, is made of lacustrine and shallow marine shales with interbedded carbonates and anhydrite beds (Klett, 2000). The top of the formation, which is laterally equivalent to the TAGS Fm of the Triassic (or Oued Mya) Basin, change facies from sandstones to interbedded sandstones and siltstones (as terminal fans and floodplain with crevasse splays), to silty shales with anhydrite facies, to salt deposits to the north (Benvegnù, 2020). [Generalized in appropriately as “clayey sandstone” for display purposes on the global paleogeography.]

Lithology Pattern:

Clayey sandstone

Relationships and Distribution

Lower contact

It unconformably overlies the Carb-F Fm. [The entire Permian through Middle Triassic is absent.]

Upper contact

It is conformably overlain by the Zarzaitine Moyen Fm.

Regional extent

Illize Basin of SE Algeria

GeoJSON

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Fossils

Age

Base is coeval with “TAGI” of Ghadames Basin, which began at beginning of the Late Triassic.

Age Span:

Beginning stage:

Carnian

Fraction up in beginning stage:

0.00

Beginning date (Ma):

237.00

Ending stage:

Rhaetian

Fraction up in the ending stage:

1.0

Ending date (Ma):

201.36

Depositional setting

Was deposited in a braided fluvial – shallow marine system (Benvegnù, 2020).

Depositional pattern:

Additional Information

The TAGI Fm has permeability of 1 Darcy and porosity over 20% (Benvegnù, 2020).

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 An unpublished MSc thesis at Universita’ degli Studi di Padova.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.