The information on this page is a summary description.
The full formal description is available here: Huet Formation
Abbreviation
HUE
Parent unit
Child units
Lithological description
Greenish to grey mudstone, siltstone and fine sandstone, poorly sorted, with characteristic orange-yellow alveoli of decalcified fossil fragments. Heterogeneous sub-metrical beds, with a faint fining upward granulometry, a slightly undulating base and sometimes vague oblique stratification. Some levels are rich in (often decalcified) macrofossils (bryozoans, brachiopods, corals, cephalopods, crinoids, cystoids and trilobites; Mailleux, 1926) that indicate a shallow shelf environment of formation. These fossils are fragmented and concentrated mostly at the base of the beds. All the features mentioned point to a tempestite deposit above storm wave base (Vanmeirhaeghe et al., 2005). This postulated rather shallow position of this unit between the covering and underlaying units, both estimated to be deep marine, could possibly be explained by a eustatic drop in sea-level postulated at this time period (Vanmeirhaeghe, 2006). The base of the formation is not observed due to presence of faults, the upper limit is quite abrupt with the Fauquez Fm.
Age
The brachiopods suggest a Caradoc or Ashgill age for the formation (Maillieux, 1926a). The cystoids from the Sennette and the Orneau valley studied by Regnell (1951) indicate an (upper) Caradoc age. The trilobites from the Orneau valley at the Lefèvre quarry, studied by Maillieux (1926a) indicated a (mid) Caradoc age. A new collection of trilobites in Grand-Manil studied by Richter and Richter (1951), point to an (early) Ashgill age. The location of the new collection is unclear and one cannot exclude that it was sampled from the covering unit, the Madot Fm. The chitinozoan assemblages containing abundantly Lagenochitina baltica, L. prussica, Belonechitina robusta and Tanuchitina bergstroemi indicate undoubtedly a late Caradoc; from which a latest Oandu (early Cheneyan, late mid Caradoc) as the oldest possible age for the Huet Fm is concluded in relation to the Baltoscandian stages (Van Grootel et al., 1997; Van Grootel & Verniers, 1998 ms). Vanmeirhaeghe et al. (2005) and Vanmeirhaeghe (2006), in their restudy of the chitinozoans, placed the formation in the F. spinifera Zone inferred by the accompanying species. In Baltoscandia, it has a late Oandu early Vormsi (mid Katian) age, whereas on British Avalonia, Vandenbroucke (2005) showed that F. spinifera Zone occurs from the upper Onnian (uppermost Caradoc, middle Katian) to the lower Cautleyan (lower Ashgill, middle Katian). Hence, they deduce a late Onnian (latest Caradoc, mid Katian) age for the Huet Formation.
Thickness
Sennette valley: minimum 60 m (Van Grootel et al., 1997; Verniers et al., 2005).
Area of occurrence
Senne basin: Sennette, Coeurq, Senne and Thisnes (Nivelles) valleys and Orneau valley; possibly in boreholes of Western Flanders (Legrand, 1968).
Type locality
Sennette valley, in the Fauquez area, along the abandoned railway section and in the abandoned Huet quarry, 230 to 300 m north of the railway bridge in Fauquez (Verniers et al., 2005, fig. 2 and 7).
Alternative names
“Formation de la grauwacke fossilifère de Fauquez” (Leriche, 1920). In the older litterature authors might have confused the macrofossil levels in the Madot Formation with the ones in the Huet Formation.
Authors
Verniers, J. & Herbosch, A.
Date
01/10/2011
Cite as
Verniers, J. & Herbosch, A. , 2011. The Huet Formation, 01/10/2011. National Commission for Stratigraphy Belgium. https://ncs.naturalsciences.be/lithostratigraphy/Huet-Formation
