AMMONITE FAUNAS, BIOSTRATIGRAPHY AND SEQUENCE STRATIGRAPHY OF THE CONIACIAN-SANTONIAN OF THE CORBIERES (NE PYRENEES)

The Coniacian-Santonian ammonite faunas oi the Corbieres are revised, and nearly 100 species/subspecies described. The Coniacian can be subd ivided into four assemblage zones, as elsewhere in Western Europe, wit h successive zones of Forresteria (Harleites) petrocoriensis, Peronice ras (Peroniceras) tridorsatum, Gauthiericeras margae and Paratexanites serratomarginatus. The base of the Santonian is a level of marked fau nal turnover. A single Assemblage Zone of Placenticeras polyopsis is r ecognized, divided into Assemblage Subzones of Nowakites carezi, Texan ites (Texanites) gallicus, and Placenticeras paraplanum. These species have partially overlapping ranges. Neither P. polyopsis nor T. (T.) g allicus range to the base of the Santonian in the Corbieres; placentic eratids and texanitids are absent from the lowest part of the stage th ere, presumably as a result of ecological exclusion. The ammonite succ ession is integrated with the sequence stratigraphy oi the interval, a nd provides a basis for assigning numerical ages to parts of the seque nce.