PALAEOENVIRONMENTAL EVOLUTION OF THE PLIO-PLEISTOCENE MONTE MARIO SUCCESSION (ROME, ITALY) INFERRED FROM OSTRACOD ASSEMBLAGES

摘要

The whole "classical" Monte Mario succession has been recovered through the excavation of the Giovanni XXIII tunnel inside the city of Rome (Italy) The succession has been sampled from the Zanclean Monte Vaticano Fm, to the Lower Pleistocene Monte Mario Fm. Well-preserved and diversified ostracod faunas have been recovered and the ostracod assemblages have been studied using community structure analyses and statistical multivariate analyses. The Monte Vaticano Fm, has been referred to a bathyal marine environment (300-350 m of depth), the most represented genera being Krithe, Parakrithe, Baildoppilata and Cytherella. The Monte Mario Fm, provided ostracod assemblages referable to littoral environments with Cirnbaurila, Aurila, Costa, Carinocytbereis, Leptocythere and Loxo-concha as dominant taxa. Within the Monte Mario Fm., three marine shallowing-up sequences have been recognised, the last two recording marginal marine conditions with shallow depths and variable salinity (dominant Cyprideis torosa). Two cold-water episodes have been recognised within the basal Monte Mario Fm. characterised by the occurrence of Arctica idandica and, within the upper level, by the presence of the northern guests Cytberopteron depressum, Bytho-cythere zetlandica, Paradoxostoma ensiforme and Paradoxostoma ab-breviatum.