3.2.4 Naninne Formation - NAN

Authors: Malaise, 1900; emend. Michot, 1954.

Description: Laminated mudstone, generally calcareous, with some micaceous siltstone or fine sandstone intercalations (Michot, 1954; Martin, 1969a); laminated fine sandy or silty shale, blue-grey, green, greenish grey or brownish grey, resistant, often calcareous, with intercalations of micaceous clayey sandstone, fine beds of red shale; intercalations of olive green shale at the top; three (quartz)keratophyre levels occur in Neuville-sous-Huy (Maes et al., 1978).

Stratotype: village of Naninne, the road to Sart-Bernard (Michot, 1934).

Area: Condroz inlier.

Thickness: ±50 m (Michot, 1957); >90 m (Vandevelde, 1976 ms; Maes et al., 1978).

Age: Graptolites of the Cyrtograptus murchisoni and the Monograptus riccartonensis biozones were described by Lassine (1913); the C. centrifugus biozone and other lower Wenlock graptolites assemblages were described by Rickards (in Maes et al., 1978). Samples from Neuville-sous-Huy contain the typical chitinozoans assemblage of the M. margaritana global biozone, however without the type species, confirming the early Wenlock age (Verniers, unpublished data).

Remarks: Synonyms: Assise de Naninne.

(J. VERNIERS)