Geochemical and Palaeoecological Analyses of Mid Pleistocene to Holocene Ostracod Assemblages from Valle di Castiglione (Italy): Palaeoenvironmental and Palaeoclimatic Assessment

摘要

Sediments from Valle di Castiglione in Italy provide a reference sequence for Middle Pleistocene to Holocene palaeoclimate reconstruction of the Mediterranean area. Stable isotope and trace element signals from ostracod valves, as well as palaeoenvironmental analyses (autoecology, community analysis and mutual ostracod temperature range), provided results that cannot be correlated with those derived from pollen and other proxy records. The lack of correlation is attributed to the peculiar geological, hydrogeological and hydrochemical setting of the Valle di Castiglione maar lake. The main trigger for the hydrochemical changes in the waterbody and, therefore, in the ostracod isotopic and trace element signatures, is likely the volcano-tectonic activity in the area. This illustrates how ostracod trace element and isotopic analyses are not the most appropriate tools for palaeoclimate reconstructions from lakes with complex hydrological features, such as some crater lakes, and demonstrates the need for care in selecting lacustrine sequences for such studies