International Field Workshop on 'The Triassic of eastern France'

Stop 3.6 - Saint-Avold (N3 road cutting): Middle Buntsandstein (‘Conglomérat
principal’ and ‘Zone limite violette’ Fms)
The basal contact of the 'Conglomérat principal' on the 'Grès vosgien' (Karlstal facies) is very even
(Fig. 36). Like at Relanges (Stop 2.2), the conglomerate is overlain by the ‘Zone limite violette’ (ZLV)
Formation which contains dolomite nodules and carnelian.
Figure 36: Outcrop of Saint Avold (see p. 7 for location).
Stop 3.7 - Sankt-Arnual (cliffs in Stiftswald): Upper Buntsandstein (‘Couches
intermédiaires’ Fm.)
This outcrop (Fig. 37) of the ‘Couches intermédiaires’ Formation has been described by Dachroth
(1972) (Fig. 38). This formation overlain the ‘Grès vosgien’ (Karlstal facies, Fig. II.3, II.4). The cliffs shows
several levels with paleosols ('violet zones') which display nearly the same characteristic than the ‘Zone
limite violette’, but carnelian is lacking. The sandstones (that contains at lot of feldspar) and conglomeratic
facies where mainly deposited as 3D and 2D megaripples forming longitudinal and transversal bars. The
paleocurrents are mainly oriented to the NE. The depositional environment is attributed to low sinuosity
rivers, within a semi-arid to sub-humid environment (temporary lakes or ponds) like attests the presence of
hydromorphic sols. Even if some paleosols have the same expression as the ‘Zone limite violette’, this
formation seems not to be present in these outcrops.
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