International Field Workshop on 'The Triassic of eastern France'

Stop 2.8 - Xirocourt (S.R.D.E. quarry): Middle Keuper (‘Dolomie de Beaumont’ Fm)
Figure 27: Location of the outcrop of Xirocourt and Mangonville
In this quarry (Fig. 27), the ‘Dolomie de Beaumont’ can be seen in its whole thickness (about 8 m),
between the 'Argiles bariolées intermédiaires' and the ‘Argiles de Chanvilles’ (Fig. I.1). The ‘Dolomie de
Beaumont’ is characterized by homogeneous microcrystalline dolomite layers with sometimes:
- very thin lenses with marine fossils (Costatoria goldfussi, gastropods or ophiurids)
- current structures
- small sulfate dissolution cavities
This facies was deposited in a lacustrine environment ('Coorong' type). The presence of current
structures, and the occasional introduction of exotic shells as well as marine water, attest high-
hydrodynamics events within the calm environment, which can be attributed to storms.
In this outcrop the deformations of dolomite layers induced by salt dissolution in the ‘Marnes irisées
inférieures’ are spectacular (Fig. 28). The ‘Argiles de Chanville’ overlain the dolostones.
Figure 28: Detail view of the deformations of dolomite layers induced by salt dissolution in the ‘Marnes irisées
inférieures’ (Xirocourt quarry).
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