Calcareous dinoflagellate cyst evolution and their response to the environmental changes related to the Messinian salinity crisis in the eastern (Cyprus) and central (Sicily) Mediterranean

Abstract

Past climatic and environmental conditions can be reconstructed by the use of different types of microfossils as proxies. Calcareous cyst producing dinoflagellates (calcareous dinoflagellates) were shown to have a high proxy potential. They provide a good fossil record. Several studies on Quaternary sediments have confirmed their usability for environmental reconstructions. However, these studies mainly focused on Quaternary records derived from surface sediments. Palaeoenvironmental reconstructions based on older fossil calcareous dinoflagellates, especially of Tertiary age and from the Mediterranean realm, are very rare. Therefore, the major aim of this thesis is to demonstrate the applicability of fossil (pre-Quaternary) calcareous dinoflagellates as a tool for palaeoenvironmental reconstructions. One of the most attractive natural laboratories to study past environmental and climatic changes is the Mediterranean Sea. Due to its nearly enclosed nature and its special geographic position, it reacts very sensitively to climatic changes. One of the most outstanding events is the Messinian salinity crisis (MSC) at the end of the Messinian stage. Because of this event, large contrasts were established in the environmental conditions, spatially and temporally. Herewith, we present the first detailed study on calcareous dinoflagellates that systematically investigated their evolution with respect to the MSC on selected land sections from the Mediterranean realm. Our first study focused on the evolution of the calcareous dinoflagellate assemblages in the Pissouri Basin prior to (upper Tortonian/pre-evaporitic Messinian) and immediately after (early Pliocene, 5.33 Ma) the MSC. In the second study, we investigated the first 100 kyrs of the earliest Pliocene (Zanclean) following the MSC, again on samples from the Pissouri Basin on Cyprus. In the third study from the central Mediterranean Caltanissetta Basin on Sicily, we again investigated the sedimentary records preceding (upper Tortonian/pre-evaporitic Messinian) and following the MSC (the first ~120 kyrs of the Pliocene). This thesis proved the applicability of fossil calcareous dinoflagellates for palaeoenvironmental reconstructions of the Late Neogene Mediterranean. It enhances the knowledge about both the spatial and temporal evolution of Neogene calcareous dinoflagellates in the central and eastern Mediterranean realm. In addition this study extends our knowledge about the environmental conditions preceding and following the MSC. Furthermore, it provides new insight into the hydrological conditions prevailing during sapropel and marl formation in the Mediterranean.