Trace fossil assemblages from the Albian phosphaterich sandstones of the Helvetic Shelf (western Alps)

In the Albian phosphate-rich sandstones of the Helvetic Shelf, three ichnofacies have been identified: 1, a Trypanites ichnofacies comprising Gastrochaenolites, Entobia, Rogerella, Trypanites and Caulostrepsis in condensed phosphatic series; 2, a Cruziana ichnofacies comprising Palaeophycus and Chondrites in relatively expanded series; 3, a Glossifungites ichnofacies characterized by glauconite-filled Thalassinoides and related to Upper Albian unconformities. The first and the second ichnofacies existed simultaneously in areas of different submarine topography created during a late Aptian-early Albian erosional period. All these ichnofacies developed in an open shelf environment and were linked to submarine unconformities and to phosphatization periods.