| Institution: | (1) UMR 6532 Hydrasa, UFR SFA Bât. Sciences Naturelles, Université de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex Poitiers, France;(2) Institut für Paläontologie der Universität Würzburg, Pleicherwall 1, 97070 Würzburg, Germany;(3) 3 Impasse des Biroulayres, 33610 Cestas, France;(4) Paläontologisches Institut, Universität Zürich, Karl Schmid-Strasse 4, 8006 Zürich, Switzerland;(5) Departament de Geologia Dinàmica, Geofísica u Paleontologie Facultat de Geologia, Universitat de Barcelona, 08071 Barcelona, Spain;(6) UMR 6046 Hydrasa, UFR SFA Bât. Sciences Naturelles, Université de Poitiers, 40 avenue du Recteur Pineau, 86022 Poitiers Cedex Poitiers, France;(7) Section de Paléontologie, Office de la culture, République et Canton du Jura, Hôtel des Halles, 2900 Porrentruy, Switzerland |
| Abstract: | The Purbeckian facies of the northern margin of the Aquitaine Basin is exposed in the Cherves-de-Cognac section (SW France), considered as basal Cretaceous in age. Two lithological units have been identified. The basal unit (U1) is composed of an alternation of gypsum and finely bedded black dolomitic marlstone, occasionally stromatolitic in nature. It represents mostly hypersaline, dolomitic tidal flat, lagoonal, and sabkha-type environments. The upper unit (U2) consists of variably fossiliferous limestone-marl alternations that contain a diverse fauna and flora. In the upper part of this unit, a 4-m-thick level has yielded a rich vertebrate fauna. The preservational quality of the vertebrate fossils varies within the section. On the basis of faunal, floral, sedimentological and mineralogical information the vertebrate remains accumulated in brackish water environments in which the influence of freshwater has progressively increased towards the top of the section. The close association of environments representing varying degrees of marine and continental influence suggest an estuarine setting. |
