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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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Hawaz Formation

Hawaz Fm

Period:

Ordovician

Age Interval:

Middle Ordovician (9)

Province:

Type Locality and Naming

Jabal Hawaz in the western part of Jabal Gargaf (Libya) (Fig. 1). Massa & Collomb, 1960. Group: Gargaf Gr

References: Massa & Collomb, 1960; Jacqué, 1963; Lababidi, 1985; Government of Niger, 1993; Mergl et al., 2001; Denis et al., 2006, 2007a, 2007b, 2010; Shalbak, 2015; Hallet, 2002, 2016.

Synonym: Tigillites sandstone Formation; Tigellites or Tigillites Unit (Government of Niger (1993). The former name of the formation was spelled Haouaz. The spelling was modified to its current form by Hallet (2002) after verifying the official name records of localities in Libya.

Lithology and Thickness

Built-up of fine to medium-grained sandstones. Medium-to-coarse grained sandstone interbedded with silty micaceous, gray, and green shale. 50 to 280 m thick.

[Figure. Stratigraphic column of the Hawaz Fm at the Type Locality (Libya) (Source: Shalbak, 2015). Note: In Libya, the Formation overlying the Hawaz is called Felar-Felar; the equivalent of the Chirfa Fm in the Djado Basin.]

Lithology Pattern:

Fine-grained sandstone

Relationships and Distribution

Lower contact

Underlain by the Ash Shabiyat Fm

Upper contact

Overlying unit is the Chirfa Fm. The contact between the Hawaz Fm and the Chirfa Fm is erosive because of glacial abrasion.

Regional extent

GeoJSON

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Fossils

Rich in trace fossils Tigillites (Harlania) and Skolithus. Poorly preserved brachiopods and bivalves.

Age

Middle Ordovician (Darriwilian in the Djado Basin according to Mergl et al. (2001). Massa & Collomb (1960) assigned it a Dapingian age at the Type Section in Libya.

Age Span:

Beginning stage:

Darriwilian

Fraction up in beginning stage:

0.0

Beginning date (Ma):

469.42

Ending stage:

Darriwilian

Fraction up in the ending stage:

1.0

Ending date (Ma):

458.18

Depositional setting

Shallow marine. This preglacial sandstone shows heavily burrowed trough cross-beds, indicative of a marine shoreface depositional environment. In addition, the excellent sorting and rounding of grains in the Hawaz Fm are consistent with a marine, non-glacial origin.

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)