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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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Teloua Formation

Teloua Fm

Period:

Triassic, Jurassic

Age Interval:

Lower Triassic-Lower Jurassic (1)

Province:
Iullemmeden Basin - Tim Mersoï Sub-basin

Type Locality and Naming

Group/Subgroup: Agadez Gr / Teloua 2 and Teloua 3 Members are part of the Goufat Subgroup. The Teloua 1 Mbr no longer belong to a Subgroup (the obsolete *Aguelal Subgroup)

References: 1959; Taquet, 1967 & 1969; Ginsburg et al., 1968; Valsardieu, 1971; Fabre et al., 1983; Moody, 1997; Abd Elmola et al., 2020; Sani et al., 2021

Synonym: "Grès du Teloua"; Teloua Sandstone Formation

Equivalent(s): The current definition of “Teloua Fm” includes the Teloua Fm of Joulia (1959). However, the conglomerates of Anou Ararène and Anou Mellé are now included in Teloua 1 Mbr, and the conglomerate of Alarcess Fm is now included in the Teloua 2 Mbr.

Lithology and Thickness

Subdivided into three Members from top to bottom: Teloua 3, Teloua 2, Teloua 1 (Figure). [However, the three Members of the Teloua Fm should be renamed since they do not meet the stratigraphic guidelines of the International Commission on Stratigraphy (Web-09).] Medium to coarse sandstones, locally intercalated with conglomerates and some beds of shales. SEM observations confirm that the sandstones of the Teloua Fm are composed of quartz, K-feldspar (microcline), Na-feldspar (albite), minor biotite, hematite, and anatase, in addition to apatite, monazite, and zircon. The upper part of the Teloua Fm (Teloua 3) is abundant quartz coated by clay minerals and has a high porosity (Abd Elmola et al., 2020). In the lower part of the Formation characterized by lower porosity, quartz and feldspar grains are coarser, more compacted, and frequently micro-fractured. Authigenic clay minerals are abundant on the dissolution surfaces and along cleavage planes of this quartz and feldspars. Large-scale dune bedding characterizes the sandstones of the Teloua Fm, with intercalated varicolored shales. Thickness: 65 m (up to 78 m in the DASA graben)

[Figure. The lithology and thickness of the three Members of the Teloua Fm within the DASA graben (Source: Modified from Sani et al., 2021).]

Lithology Pattern:

Sandstone

Relationships and Distribution

Lower contact

Unconformably overlies the Moradi Fm of the Izégouandane Gr (the Aokaré Mbr of the Moradi Fm when present).

Upper contact

Overlying unit is the Mousseden Fm or unconformably overlain by the Tchirezrine Fm (Tchirezrine 1 Mbr).

Regional extent

GeoJSON

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Fossils

Chirotherium trace fossils (Ginsburg et al. (1968); Taquet (1967, 1969))

Age

Lower Triassic-Lower Jurassic (Fabre et al., 1983). Schematic strat section (LeBlanc, 2022, Lexicon) implies Middle Triassic is absent between Tel 1 Mbr and Tel 2 Mbr

Age Span:

Beginning stage:

Induan

Fraction up in beginning stage:

0.0

Beginning date (Ma):

251.90

Ending stage:

Sinemurian

Fraction up in the ending stage:

1.0

Ending date (Ma):

192.90

Depositional setting

Continental fluvio-lacustrine

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)