The Circalittoral/Bathyal paleocommunities in the Middle Pliocene of Northern Italy: the case of Korobkovia oblunga-Jupiteria concava Paleocommunity type

The Piacenzian section of Campore (Northern Italy) has been used to determine the paleoecological significance of the muddy upper bathyal mollusc associations of the Mediterranean Pliocene. By employing computer-based strategies (cluster and rarefaction analyses) a Korobkovia oblonga–Jupiteria concava paleocommunity type (KJ pt) has been defined. The KJ pt comprises a mosaic of local paleocommunities and paleocommunities whose taxonomic and trophic structures are mainly controlled by oxygen content, sediment accumulation rate, turbidity, and trophic resources. Comparison with mollusc coenoclines recognized in Northern Italy (Rio Merli and River Reno sections) suggests that the KJ pt is bracketed between the deepest muddy circalittoral paleocommunities and the deeper bathyal Bathyspinula excisa–Austrotindaria pusio unit (preliminarily described for the Rio Merli section). The KJ pt is very common in Northern Italy outcrops even though reported by previous authors with different names. We interpret this paleocommunity, which does not go beyond the Middle Pliocene, as the last evidence of an upper bathyal environment in the Neogene climatic-oceanographic regime of the Mediterranean.