Chalk Biozone 17 - Triblastula utinensis
Age: Early to late Maastrichtian.
Macrofaunal correlation: The upper B. occidentalis Zone to the lower B. junior Zone.
Definition: The interval between the LAD of Alterbidinium acutulum to the LAD of Triblastula utinensis.
Comments: The LAD of Triblastula utinensis in the late Maastrichtian is a well-established biomarker (Kjellström, 1973; Wilson, 1974; Robaszynski et al., 1983; 1985; Costa & Davey, 1992; Schiøler & Wilson, 1993; Schiøler et al., 1997; Foucher & Monteil, 1998). The LADs of Gillinia hymenophora and Hystrichodinium pulchrum occur within this biozone, at the Lower Maastrichtian-Upper Maastrichtian boundary (Wilson, 1974; Robaszynski et al., 1985; Foucher & Monteil, 1998).
Lithostratigraphical correlation: The Tor Formation (North Sea).