Les formations mésozoïques à Charophytes ( Jurassique moyen-Crétacé inférieur) de la marge téthysienne nord-occidentale ( SE de la France, Suisse occidentale, NE de l'Espagne) . Sédimentologie, micropaléontologie, biostratigraphie.

摘要

The main topic of this work concerns the micropaleontological and sedimentological study of the emersive deposits on the Jura platform (S.-E. France and western Switzerland) since the Middle Jurassic to the Lower Cretaceous (Purbeckian and Wealdian facies). By additional data of selected outcrops in N.-E. Spain (Maestrazgo) and S.-E. France (Basse-Provence), a continental biozonation mainly based on the Charophytes and a new phylogenetic diagram of the Clavatoraceae (Charophytes) are set for the Upper Jurassic - Cretaceous of the Western Europe. Moreover, the polymorphous gyrogonites of the Porocharaceae and Characeae (Charophytes) is underlined with a taxonomic review. After a comparison including the Jurassic-Cretaceous fossi! data and the material collected in similar recent environments, this polymorphism is related to the interaction of sorne fluctuating ecologic parameters (salinity, pH, lighting, temperature) on the growth of the Charophytes thallus and fructifications. The micropaleontological and sedimentological analysis of the Jura platform's Mesozoic emersive deposits allows to notice likewise a Lower Cretaceous tectonic activity related to a tardi-hercynian origin and connected with the Neo-Cimmerian phase, as well as to recognize a subtropical climate with alternated seasonal dry and wet periods in the Middle Jurassic - Lower Cretaceous interval. The very particular occurrence in the Jura Mountains of scarce Dinosaurs remains (Allosaurus) and some Characeae (Aclistochara bransoni) agrees to postulate during the Upper Jurassic and the lowermost Cretaceous biological exchanges between the northern Tethyan margin (Eurasia) and North America. More precisely, other correlation tools (Ostracods, Charophytes, Dinokysts, Ammonites) from respectively Tethyan or Boreal realms indicate the evidence of connections with the Jura platform in the lowermost Cretaceous (Berriasian-Valanginian / Volgian-Ryazanian). As conclusions, this study introduces a sequential interpretation of the Jurassic-Cretaceous coastal deposits on the Jura platform and evaluates the share of the glacio-eustatic climatic cycles or of the continental drift inducing the brackish-Iacustrine emersive facies on the continental margins and cratonic areas . At last, the phylogenetic lineage of the Hemiglobator-Globator (Clavatoraceae, Charophytes) is used as a significant exemple to argue about the neo-darwinist theory of Evolution and the creationism, apparently conflicting but in fact complementary.