Palaeofocus 3: Die Molluskenfauna (Hemmoorium, Untermiozän) aus der Kiesgrube Krinke bei Werder (Nordwest-Niedersachsen) [The Mollusc Fauna (Hemmoorian, Lower Miocene) from the Gravel Pit Krinke near Werder (Northwest Lower Saxony)]

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Language: German with English summary

Gravels from the Krinke pit at Werder near Achim in the Bremen area contain Miocene fossils from underlying Hemmoorian strata. The molluscs (87 Bivalvia, 5 Scaphopoda, one Amphineura, 254 Gastropoda, one Cephalopoda) of this locality are described and illustrated.

The strata containing the fossils are inaccessible to direct observation because the gravel is extracted only by dredging. Therefore, the fauna's stratigraphic position has been inferred from the mollusc zonation of Hinsch (1977) and the Nassariid zonation of Gürs (2002a). From the Nassariid zonation, which is highly practicable for the Hemmoorian, the deposition interval appears to comprise almost completely the Nassarius cimbricus (Ravn, 1907) zone and parts of the Nassarius schroederi (Kautsky, 1925) zone. A conspicuously high fraction of species tolerating a (relatively) strongly reduced salinity is observed.

The fauna at Werder very closely resembles that at the classical outcrops near Hemmoor (north-western Lower Saxony) as well as the faunas described from numerous wells that intersected strata of the same age in north-western Lower Saxony, western and northern Schleswig-Holstein, and southern Jutland (Danmark).

The remarkable faunal diversity of the North Sea Basin Hemmoorian has generally been explained by migration of species from southern basins. The majority of new species appears to have migrated from south-western France (Aquitaine) whereas other species are rather known from the Paratethys. The Werder material contains species providing new evidence for a controversally discussed direct connection between the North Sea Basin and the Paratethys.

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