A new ammonite fauna from NE Germany - evidence for an Early Albian cooling and the initial transgression in the Danish-Polish Trough

Abstract

A new Early Albian ammonite fauna is described from erratic boulders of morainal plain deposits at Wolgast-Hohendorf near Greifswald in north-eastern Germany. They contain species indicative essentially of the Proleymeriella schrammeni Zone, the Leymeriella tardefurcata Zone and possibly the earliest Douvilleiceras mammillatum Superzone. This dates the transgressive glauconitic sandstones, representing a major pulse of the initial Cretaceous transgressive history in the Danish-Polish Trough. The largest element of the ammonite fauna consists of Hypacanthoplites elegans, a species that is fairly widely distributed but endemic to Europe and is particularly common in the Lower Saxony Basin. A significant part of the fauna indicates an Arctic incursion of ammonites during the Early Albian, with Arcthoplites jachromensis and Grycia? sp. We identify some relations to the Early Albian ammonite fauna of Bornholm which is revised. The Hohendorf assemblage also yields the first Bellidiscus assemblage recorded outside of the Mangyshlak Peninsula in Kazakhstan that stresses its character as fairly cosmopolitan. Palaeogeographically the presence of a small Early Albian seaway from the Arctic to the Danish-Polish Trough which connects also faunas of the southern rim of the Scandinavian (Baltic) Shield to the southern rim of the Russian Platform is confirmed. The record of cool temperate ammonites among the material at hand might be explained by cool polar regions during the Early Albian and agrees with data from other ammonite faunas recorded from Europe.