Chitinozoan biostratigraphy of the upper Ordovician Fagelsang GSSP, Scania, southern Sweden

In the Fagelsang section, the new Global Stratotype Section and Point (GSSP) for the base of the Upper Ordovician Series, 22 samples from the E 14 (a, b and c) and E 15 outcrops have been studied for chitinozoans. They yield rich and rather diverse species assemblages of this microfossil group. The approximately 16-m-thick sampled part of the section can be subdivided, from bottom to top, into two biozones and a subbiozone: the Lauftldochitina stentor zone, the Eisenackitina rhenana subzone and the Lagenochitina dalbyensis zone. The boundary between the lowest biozone and the subzone is situated 1.7 in below the marker Fagelsang Phosphorite bed, thus only slightly lower (0.3 m) than the base of the Nemagraptus gracilis graptolite biozone, which defines the base of the Upper Ordovician Series. The base of the L. dalbyensis zone is located just above the Fagelsang Phosphorite, remarkably low compared to the graptolite biostratigraphy. It is evident that the chitinozoan biozonation provides an additional tool to recognise the base of the Upper Ordovician in this section. Furthermore, a distinct faunal change is shown across the phosphorite bed, possibly indicating a hiatus. (C) 2004 Elsevier B.V. All rights reserved.