Ostracods and bivalves from an Upper Pleistocene (Tyrrhenian) marine terrace near Altınova (İzmit Province, Turkey)

Ostracods and bivalves from two samples collected near Altinova (Izmit Province, Turkey) are studied. The sample sediment consists of coarse to fi ne grained sands and comes from the oldest part of the Marmara Formation, a succession of Late Pleistocene marine terraces. The composition of the ostracod fauna corroborates the Tyrrhenian radiometric age of the succession. The ostracod associations are composed predominantly of heavily calcifi ed and ornamented genera, which indicate a nearshore, inner neritic depositional environment. The bivalve assemblages, containing byssate and cementing epifaunal and infaunal taxa, suggest a combination of rocky coastal environment and shallow marine clastic deposits. Faunal composition and shell dimensions of the bivalves are indicative of reduced salinity.