Latest Pliensbachian –Early Toarcian brachiopod assemblages from the Peniche section (Portugal) and their correlation

Abstract

In the present paper we describe the distribution of brachiopods in the proposed Toarcian GSSP (Global Boundary Stratotype Section and Point) at Peniche. We differentiated four assemblages in the stratigraphic interval from the upper Emaciatum Zone of the Pliensbachian to the Levisoni Zone of the Toarcian. Assemblage 1 clearly presents Northwestern European affinities, with many species that are also present in Southern England. In the last levels of the Pliensbachian and in the Mirabile Subzone (the first level of the Toarcian), Assemblage 2 contains taxa that still present Northwestern European affinities, but with a more restricted, even endemic, distribution. The majority of the species in these levels are known from the Iberian Range in Spain and other neighboring basins. An important faunal change takes place in the Semicelatum Subzone, coinciding with the base of the Cabo Carvoeiro Formation, giving rise to Assemblage 3. In this assemblage we observed a clear decrease in the size of the specimens, coinciding with the establishment of the "Koninckella Fauna"; this fauna is found in several localities in both Northwestern European and Mediterranean areas where the paleoenvironment is relatively deep or poorly oxygenated. Brachiopods disappear in Peniche just above the Polymorphum -Levisoni zonal boundary, as has been observed in several other localities in Western Tethys. Their renewal is marked by the presence of Soaresirhychia bouchardi several meters above the extinction level, constituting Assemblage 4.