2.5.2 Lust Formation - LST

Authors: Legrand, 1961a; Martin, 1969a.

Description: Shale mostly light grey, sometimes very light greenish grey, seldom black, interbedded by many fine layers or laminae of clayey siltstone or fine sandstone, finely laminated. It differs from the Deerlijk Fm by the large relative proportion of sandstone beds (Legrand, 1961a; Martin, 1969a).

Stratotype: Kortrijk, brewery Lust borehole (BGS N° 83W44) between depths of -150 to -190 m.

Area: Area in the subsurface of the SW of the Brabant Massif (Kortrijk, brewery Lust borehole, St-Antonius borehole; Steenkerke borehole).

Thickness: >54 m.

Age: Graptolites described by Legrand (1961a) indicated a M. turriculatus and M. crispus biozones; after a restudy by Zalasiewicz in Van Grootel et al. (1998) the guerichi biozone (lower part of the “traditional” turriculatus biozone) with the gemmatus, ?renaudi and ?utilis subzones and the crispus biozone were recognised. The rich chitinozoan assemblages indicate a E. dolioliformis global biozone. Both groups indicate the lower half of the Telychian (upper Llandovery) (Van Grootel, 1990 ms; Van Grootel et al., 1998).

(J. VERNIERS)