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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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Tim Mersoï Formation

Tim Mersoï Fm

Period:

Carboniferous

Age Interval:

Lower Carboniferous (Mississippian – Upper Visean) (1)

Province:
Iullemmeden Basin - Tim Mersoï Sub-basin

Type Locality and Naming

Type locality at "Reg du Tim Mersoï", about fifty km SE of In Guezzam (Niger) (Section A in Fig. 1). Group: Terada Gr

[Figure 1. Section A) Touaret - Tim Mersoï area. Section B) Talak area. 1) Precambrian. 2) Lower Paleozoic to Middle Devonian 3) Upper Devonian and Lower Carboniferous (Taberia Fm, Farrazekat Fm and Teragh Fm). 4) Lower Carboniferous (Tim Mersoï Fm & Talak Fm). *a to *k are the main fossiliferous horizons (Source: Modified after Martinez Diaz, 1983).]

References: Lessard, 1961 emend. Claret & Tempère, 1968; Valsardieu, 1971; Legrand-Blain, 1974; Fabre et al., 1983; Martinez Diaz, 1983.

Synonym: Tim Mersoi Fm, Tin Mersoï (misspelling). Equivalent(s): Talak Fm; Aoulingen Fm

Lithology and Thickness

Clayey silt, and some gypsum; it contains thin levels of lumachellic calcareous sandstone, more rarely sandstone, and, at its upper part, clay pebbles and ferruginous nodules. It is slightly eroded at its top. Thickness: 445 to 715 m. On page 51 of Valsardieu (1971), it is stated a thickness of 270 m in the area of Touaret.

[Figure 2. Tim Mersoï Fm transgression-transition from the underlying sandstones of the In Ateï Fm (sandstone – now part of the Teragh Fm) interval within the Lower Carboniferous (Lower Visean) of Algeria (Source: Mammar, 2012).]

Lithology Pattern:

Siltstone

Relationships and Distribution

Lower contact

Underlain by the Teragh Fm (see Figure 2).

Upper contact

Overlain by the Guezouman Fm

Regional extent

GeoJSON

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Fossils

Brachiopods (Histosyrinx valrini and Marginalia betainensis (Legrand-Blain, 1974) Spiriferids (Spirifer duplicostata, Spirifer striatus, Syringothyris cuspidata)). Fauna of Productids (Productus cora, Productus antiquatus, Productus semireticulatus) (Valsardieu, 1971).

Age

Lower Carboniferous (Mississippian – Upper Visean; same as the Talak Fm). Claret & Tempère, 1968. (See Talak Fm for more details).

Age Span:

Beginning stage:

Visean

Fraction up in beginning stage:

0.5

Beginning date (Ma):

338.54

Ending stage:

Visean

Fraction up in the ending stage:

0.8

Ending date (Ma):

333.62

Depositional setting

Marine

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)