Marine climate archives and geochemical proxies: a review and future investigations on the Mediterranean Sea

Paleoclimate research based on the investigation of geochemical proxies in marine climate archives has been growing considerably during the last two decades, due to the development of more precise analytical systems. Thermal ionization and inductively coupled plasma mass spectrometers, equipped with multi-collectors, enable to obtain precise and accurate isotopic data, an essential requirement for reliable reconstructions of the physical and chemical marine parameters. In the last 5 years, part of the paleoclimate investigation focused on the Mediterranean has been carried out using these cutting-edge analytical techniques through international collaborations among Italian, Australian and American scientists. Specimens of shallowand deep-water corals collected in the Mediterranean Sea, in the Atlantic and Pacific Oceans, have been analysed with laser ablation and solution ICP-MS and with a thermal ionization mass spectrometer. The correlation between Li, Mg, P, normalized to Ca, and the Nd and B isotopic composition of the coral skeletons with the most important marine parameters has enabled to develop and validate new geochemical proxies. The derived calibration equations can now be applied to well-dated fossil corals with the aim to reconstruct the climate variations in the past. This article reviews some of the principal results achieved in the last 5 years by the authors and present some future directions on the application of geochemistry to coral investigation.