Gara Louki Fm
Period:
Ordovician, Silurian
Age Interval:
Sandbian (?) – Aeronian (?).
Province:
Illizi Basin
Type Locality and Naming
Synonym: Unit IV in Illizi Basin (Benvegnù, 2020).
References: Benvegnù, 2020
Lithology and Thickness
It was deposited at the end of the glacial cycle, when the North-African platform was near the South Pole, as the icecap retreated. It is the lateral equivalent of the Memouniat Fm and upper Jaferah Fm in the Ghadames Basin. It is characterized by the deposition of sandy limestone at its base that is truncated by the Glacial Unconformity – after which shales were deposited, and finally capped by sandstones (Benvegnù, 2020). Generalized as clayey limestone (Fig 1.4 of Benvegnù, 2020).
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Lithology Pattern:
Clayey limestone
Relationships and Distribution
Lower contact
It conformably overlies the Edjeleh Fm.
Upper contact
It is conformably overlain by the Argileux Fm.
Regional extent
Illize Basin of SE Algeria
GeoJSON
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Fossils
Age
Late Ordovician and early Silurian but with glacial unconformity for the Hirnantian
Age Span:
Beginning stage:
Sandbian
Fraction up in beginning stage:
0.00
Beginning date (Ma):
458.18
Ending stage:
Aeronian
Fraction up in the ending stage:
1.0
Ending date (Ma):
438.59
Depositional setting
Glacial – Basal lowstand system (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 An unpublished MSc thesis at Universita’ degli Studi di Padova.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.