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Zeiss A. (1983) Zur Frage der Äquivalenz der Stufen Tithon/Berrias/Wolga/Portland in Eurasien und Amerika. Ein Beitrag zur Klärung der weltweiten Korrelation der Jura-/Kreide-Grenzschichten im marinen Bereich // Zitteliana. Vol. 10. Pp. 427-438.
The worldwide regression during the Upper Tithonian and Lower Berriasian caused a continous reduction of the seaways connecting the Boreal and the Mediterranean (resp. Pacific) realm. Besides that, connections between the different parts of the seas within these realms became more and more restricted, so that a number of provincial or subprovincial faunal developments took place. Around the Jurassic-/Cretaceous Boundary apparently only two seaways were in existence: the one along the westside of North-America (with overlapping of pacific and (sub-)boreal faunal elements), the other via the Caucasus and adjacent areas (with overlapping of submediterranean and subboreal elements). Neglection of such seaways with overlapping of faunes by a number of European authors engaged with establishing of interregional correlation charts seems to be one of the reasons of the many different opinions on this subject. Too, the rapid increase of knowledges not always has been kept in mind; thus outdated subdivisions were used, where new ones were already available provoking still more complications. Also some authors used only one group of guide-fossils, while it is necessary that as many guide fossil groups as possible are considered, if conditions of correlation are such difficult as at the Jurassic/Cretaceous boundary. Further, problems of definition and nomenclature of the uppermost Jurassic stage impaired the correlation The aim of this paper is to inform about the present status of these problems and to provide a revised table (with explanations) for a worldwide correlation of marine zonal sequences of some of the most important provinces and subprovinces of the above mentioned realms (Tab. 1). This has been established by use of the most important guide fossil groups in the Jurassic-/Cretaceous border beds (ammonites, buchias and calpionellids).