Biogeographic differentiation of the Oxfordian and Early Kimmeridgian ammonite faunas of Europe, and its stratigraphic consequences

Abstract

The Oxfordian and Early Kimmeridgian ammonite provincionalism, gradually arising through that time, makes it necessary to set up the separate zonal schemes for different parts of Europe. Besides the generally known differences in ammonite faunas between four distinct bioprovinces, there is a growing evidence that, beginning from the Middle Oxfordian, the ammonite faunas of the western part of the Submediterranean Province differ from those of the eastern part of this province. The two subprovinces, the Iberian-Aquitaine Subprovince and the German-Polish Subprovince, are thus recognized within the Submediterranean Province. The correlation of the Boreal and Subboreal zonal schemes with the Submediterranean one in the Upper Oxfordian and Lower Kimmeridgian is based on the invasions of Boreal ammonites of the genus Amoeboceras into the Submediterranean Province, and on the comparison of the evolutionary development of the family Aulacostephanidae in the Subboreal and Submediterranean Provinces. The successive migration waves of Boreal and Subboreal ammonites into the Submediterranean Province corresponded therein to the marked changes in ammonite faunas of Submediterranean/Mediterranean origin which could also be related with faunal invasions. These changes in ammonite faunas have possibly been controlled by transgressive impulses during the Late Oxfordian - Early Kimmeridgian in Europe.