The information on this page is a summary description.
The full formal description is available here: Ottré Formation
| Abbreviation | OTT |
| Parent unit | Salm Group |
| Child units | |
| Lithological description | Purplish slate and silty slate (called “quartzophyllade” in the older literature) subdivided into 3 members. The Meuville Mbr (MEU, old: Sm2a), in the north: red or purple slate and “quartzophyllade”, purple slate with calcareous nodules, garnet bearing slate. In the north a gradual transition exists between the green “quartzophyllade” of the Lierneux Mbr and the purple “quartzophyllade” of the Meuville Mbr. The Les Plattes Mbr (PLA, old: Sm2b), in the north: purplish slate and sandy “quartzophyllade”, calcareous levels with iron and manganese nodules. In the south: “quartzophyllade”, purple or with purple patches containing levels with interstratified coticule, andalusite, garnet and volcanic rocks. The base is formed by a slaty sandstone, light green, with coarse ottrelite crystals. The Colanhan Mbr (COL, old: Sm2c), in the north: purple coloured slate with a few levels of green slate; in the south: purple and green compact layered slates, containing ottrelite. |
| Age | Neither micro- nor macrofossils observed; by geometry supposedly between Late Tremadoc (Early Ordovician) and Mid Ordovician. |
| Thickness | Colanhan Mbr: 50 m; Les Plattes Mbr: 30 m; Meuville Mbr: 70 m; total thickness: 150 m. |
| Area of occurrence | See description. |
| Type locality | Not yet defined; type area in the syncline south of Ottré; type area of the Meuville Mbr: outcrops in the Lienne valley north of Chevron; type area of the Les Plattes Mbr: abandoned or active quarries for the “coticule” between Hébronval and Bihain; type area of the Colanhan Mbr: the hill south of Lierneux between the villages of Verleumont and Hébronval and the northern flank of the crest south-west of Vielsalm. |
| Alternative names | Sm2 |
| Authors | Verniers, J., Herbosch, A., Vanguestaine, M., Geukes, F., Delcambre, B., Pingot, J.-L., Belanger, I., Hennebert, M., Debacker, T., Sintubin, M. & De Vos, W. |
| Date | 01/01/2001 |
| Cite as | Verniers, J., Herbosch, A., Vanguestaine, M., Geukes, F., Delcambre, B., Pingot, J.-L., Belanger, I., Hennebert, M., Debacker, T., Sintubin, M. & De Vos, W., 2001. The Ottré Formation, 01/01/2001. National Commission for Stratigraphy Belgium. https://ncs.naturalsciences.be/lithostratigraphy/Ottre-Formation |
| Additional information |
