2.7 Sleen Formation

Authors: van Adrichem Boogaert & Kouwe, 1993.

Description: Open marine, grey, locally sandy or silty claystones. The appearance of red claystones and dolomitic mudstones marks the contact with the underlying Keuper Formation.

Boundaries: top: passing concordantly into Aalburg Formation; base: disconformably overlying Keuper Formation.

Stratotype: Parastratotypes in Belgium: well KB99 Neeroeteren, well KB 198 Molenbeersel.

Area: Roer Valley Graben ; removed by erosion from Campine Basin and eastern Brabant Massif.

Thickness: ca. 30 m.

Age:  Uppermost  Triassic, Rhaetian , dated  by  Legrand ( 1961 and in Delmer, 1963) and by M. Roche (personal communication)  on  the  basis  of   macrofossils   and palynomorphs.

Remarks: The lithological and palynostratigraphical resemblance to the Rhaetian in the Gaume (SE Belgium, Paris Basin) strongly suggests a connection over the Ardennes and eastern Brabant Massif active during time of deposition (M. Roche, personal communication).

This is the first mention of the Sleen Formation in Belgium. The Sleen and Aalburg Formations are distinguished on the basis of the Dutch stratigraphical nomenclature. Limited data from Belgium do not yet allow a clear distinction.