Molluscan palaeoecology and sedimentological features: an integrated approach from the Miocene Meduna section, northern Italy

Abstract

Molluscs were studied to reconstruct the palaeoenvironmental conditions of the Miocene sequence of the Torrente Meduna area (Friuli, northern Italy), and to compare palaeobiological results with those of an earlier sedimentological analysis. The study identifies six fossil communities and relevant individual assemblages, and ascribes them to palaeobiocoenoses comparable to modern Mediterranean ones introduced by French marine ecologists: (1) Chlamys praescabriuscula community; (2) Pecten burdigalensis community; (3) Loripes dentatus assemblage; (4) Protoma rotifera community; (5) Benus-Ancilla assemblage; and (6) Venus-Conus community. The palaeobiological analysis demonstrates that the entire Miocene sequence, up to the Late Tortonian or very early Messinian, was deposited within the infralittoral zone, at shallow to very shallow depths onto wave-influenced bottoms. The greatest water depth occurred during Early Tortonian and was of approximately 25 m. Palaeobiological and sedimentological methods provide different sets of information which complement each other efficiently. General environmental conditions (in this case, a delta-influenced environment) can best be reconstructed on the basis of sedimentological data. However, specific aspects of the environment, primarily palaeobathymetry, may only be interpreted by means of through palaeobiological analysis.