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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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Mourizidié Formation

Mourizidié Fm

Period:

Cambrian

Age Interval:

Lower Cambrian (9)

Province:
Djado Basin

Type Locality and Naming

Jacqué, 1963.

References: Jacqué, 1963; Fabre et al., 1983; Government of Niger, 1993; Mergl et al., 2000, 2001; Shalbak, 2015; Hallet, 2002, 2016.

Synonym: Mourizidie Fm; Equivalent(s): “Basal Unit” as per Government of Niger (1993);

Lithology and Thickness

Low-grade metamorphic to non-metamorphic rocks. Jacqué (1963) uses this term for a set of arkosic sandstones and predominantly wine-red siltstones. Thickness: ~10 m (Fabre et al., 1983).

[Figure 1: Stratigraphic chart for the sedimentary infill and the main tectonic events recorded in the southern Murzuq basin of Libya and adapted for the Djado Basin of Niger (Source: modified from Shalbak, 2015)]

Lithology Pattern:

Fine-grained sandstone

Relationships and Distribution

Lower contact

Precambrian is below.

Upper contact

Overlain by the Hasawnah Fm (Gargaf Gr)

Regional extent

GeoJSON

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Fossils

none

Age

Lower Cambrian (see “Additional information”)

Age Span:

Beginning stage:

Fortunian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

538.80

Ending stage:

Cambrian Stage 2

Fraction up in the ending stage:

1.0

Ending date (Ma):

521.00

Depositional setting

Continental

Depositional pattern:

Additional Information

Jacqué (1963) interpreted this Formation as infra-Cambrian for the following reasons:

It is placed in angular discordance on the folded Pharusian basement, partially granitized and covered by slightly discordant Cambrian-Ordovician sandstones (Gargaf Group).
Some of its petrographic and lithological characters oppose it to Cambrian-Ordovician sandstones.

Although Jacqué did not see volcanic flows, the basic conglomerate of Cambrian-Ordovician sandstones that the formation supports contains rolled pebbles of devitrified rhyolites; these acid flows are known and dated as Cambrian in several regions of the Sahara.

Fabre et al. (1983, page 123) state that the “level 0” at the base of the Cambrian-Ordovician of the Djado Basin is “represented by fine to medium sandstone, well-sorted, often purple, which would be the equivalent of the Mourizidié formation in Libya. These sandstones, sometimes attached to the Upper Precambrian (Infracambrian), are rather to be compared to the purple sequence of the Ahaggar of Cambrian age which represents the molasse of the pan-African chain”.

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)