Paleoenvironmental reconstruction of marginal marine environments from combined paleoecological and geochemical analyses on ostracods

Abstract

Marginal marine environments are complex systems, which show physico-chemical instability due to seawater/fresh water interactions. During the Quaternary these features have been more complicated by the global climatic and sea level variations. Consequently, the use of ostracod shell chemistry (trace elements, δ 13 C, δ 18 O and 87 Sr/ 86 Sr) to decode the paleohydrochemical characters often is not enough to understand the paleoenvironmental changes. But, if geochemistry is coupled with the classic taxonomical/paleoecological analyses, it may provide a more unambiguous reconstruction. Combined geochemical and paleoecological analyses on ostracods were applied to two boreholes drilled in Quaternary sequences in central Italy. At Migliara (Latium), the inferred salinity deduced from ecology and geochemical data on Cyprideis shells suggests a simple mixing between marine and fresh water, mainly caused by sea-level oscillations. The lack of correlation between ostracod ecology and geochemical data in the Albinia core (Tuscany) can be explained by the mixing of waters from at least three different sources.