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Cenomanian ammonites from the condensed deposits of the Helvetic Domain (western Alps, France and Switzerland)

Delamette, M. ; Kennedy, W. J.

In: Journal of Paleontology, 1991, vol. 65, no. 3, p. 435-465

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    Titre
    • Cenomanian ammonites from the condensed deposits of the Helvetic Domain (western Alps, France and Switzerland)
    Auteur
    • Delamette, M.. Institut de Géologie, Université de Fribourg, Pérolles, 1700 Fribourg, Switzerland
    • Kennedy, W. J.. Geological Collections, University Museum, Parks Road, Oxford OX1 3PR, United Kingdom
    Type de document
    • Postprint
    Langue
    • Anglais
    Publié dans
    • Journal of Paleontology, 1991, vol. 65, no. 3, p. 435-465. Cambridge University Press
    Autre version électronique
    Classification
    • Sciences de la terre
    Identifiant OAI-PMH
    • oai:doc.rero.ch:290018
    Summary
    The Cenomanian ammonites of the Helvetic Domain (French-Swiss Western Alps) are revised and illustrated for the first time since the middle of the Nineteenth Century. The faunas occur in remarkable condensed hemipelagic glauconite-rich biomicrites that also contain planktic foraminifera and small stromatolites. Thirty-three ammonite species referred to 15 genera are described; the assemblage extends from the lower part of the Lower Cenomanian Mantelliceras mantelli Zone (Neostlingoceras carcitanense Subzone) to the lower part of the Middle Cenomanian Acanthoceras rhotomagense Zone (Turrilites costatus Subzone). The assemblage comprises 57 percent trachyostracous forms, 41 percent heteromorphs of the standard N.W. European sequence, and 2 percent leiostracous forms, which inhabited an external shelf biome. The biogeographic affinity of this fauna is essentially cosmopolitan (69 percent), but 31 percent of the specimens belong to the European Boreal biota, with no Tethyan taxa