Integrated paleohydrology reconstruction and Pliocene climate variability in Cyprus Island (eastern Mediterranean)

Abstract

Abstract The present study describes the Pliocene paleoenvironmental evolution and the main paleoclimatic trends of Cyprus Island (southeastern Mediterranean) reconstructed using planktonic foraminifera. The Essovouyes-Exovouyes section, which is located on the boundary of Messaoria basin in the north and Larnaka basin in the south, corresponds to a continuous record from 5.21 to 1.8 Ma and therefore provides good data for the paleoclimatic reconstruction northeast of the Troodos mountain range. The sedimentary sequence of the studied section is about 90 meters thick and characterized of pinkish to brownish massive marls, rhythmic sedimentary cycles of yellow to light grey homogeneous marls and brownish organic-rich laminated layers, brown to light grey sandy marls, light yellow marly sands enriched in macrofossils, and yellow massive fine- to coarse-grained bioclastic calcarenites at the top. We particularly focused on its middle part (3.9-3.0 Ma time interval), which consists of well-preserved cyclic marine sediments, including organic-rich laminated brownish sapropelitic layers alternating with grey homogeneous marls. This part of the section was measured and sampled at 0.1 to 0.55 m intervals, which allowed us to perform a detailed biostratigraphic analysis. Seven astronomically dated planktonic foraminiferal bioevents were recognized and constrained the age model of the studied interval through the linear interpolation. Within this biostratigraphic framework, the first occurrence of Globorotalia crassaformis is highlighted in this study and confirms the presence of the Zanclean/Piacenzian boundary (3.6 Ma). Integrated micropaleontological, sedimentological, and geochemical (Total Organic Carbon; TOC, and stable oxygen and carbon isotope; δ18O, δ13C) analyses revealed the presence of numerous cycles that resulted in the sapropelitic/homogeneous marl alternations. The sapropelites developed around the Zanclean/Piacenzian boundary suggest a climate characterized by fluctuations of warm/temperate to humid conditions associated with a highly stratified water column at times of precession minima. Moreover, long term trends in oxygen isotopes are correlated with the sea surface temperature (SST) record derived from the planktonic foraminiferal assemblages (Planktonic Paleoclimatic Curve; PPC) and mostly reflect changes in global climatic conditions, with a more local or regional signal superimposed on this record. In particular, both the PPC and δ18O records indicate three distinct warm periods interrupted by two cooling events centred at 3.62 and 3.54-3.36 Ma respectively. Furthermore, the statistical analysis of the planktonic foraminifera revealed that the surface primary productivity and temperature show the highest explanatory power for their distribution and influence the hydrological regime of the studied area. Overall, this work confirms that multidisciplinary strategies and multiproxy study performed on Neogene sections can provide a powerful tool for monitoring the palaeoclimatic evolution of the eastern Mediterranean in relation to the global climatic system over the Pliocene.