The Albian stage and substage boundaries

Abstract

Following discussions at the Second International Symposium on Cretaceous Stage Boundaries, held in Brussels, 8-16 September 1995, the Working Group has identified two possible GSSP's (Global Boundary Stratotype Sections and Points) for the base of the Albian Stage. One of these, located at Vohrum (North Germany), was fully discussed at the Copenhagen Symposium in 1983 and, if selected, would use the appearance of Leymeriella schrammeni for the definition of the base of the Albian Stage. Unfortunately, apart from the ammonite information, there appears to be few other biostratigraphic data available for that succession. An alternative stratotype section, in the Vocontian Trough of S.E. France, offers a wider range of descriptors, including ammonites, calcareous nannofossils, planktonic foraminifera, dinoflagellate cysts and oceanic anoxic events [e.g., the Paquier Event]. Once data for both sections are fully compiled a boundary is clearly definable. The bases of the Middle Albian and Upper Albian were also discussed, the decision having been taken to retain the tripartite subdivision of the Albian Stage. A possible GSSP for the base of the Middle Albian is the Côtes Noires succession on the River Marne near St-Dizier [Haute-Marne, France]. While the boundary may be identified by the appearance of Lyelliceras lyelli further work on the proposed GSSP needs to be done [possibly by the GFC]. The base of the Upper Albian is probably best defined by the appearance of Dipoloceras cristatum. There are two potential GSSP's; Wissant [Pas-de-Calais, France] and Folkestone [Kent, England] - both listed by d'ORBIGNY in the initial definition of the Stage. Either of these sections could act as the GSSP, although it is recognised that the succession at Folkestone is very condensed. An alternative locality, in the Vocontian Trough [S.E.France] may prove more suitable and information on all three locations will be gathered before a final decision is taken.