Land-Ocean Correlation of Orbital-Scale Climatic Changes in the Western Mediterranean during MIS 1/2 and 11/12

The interval between 405 and 340 thousand years before present has been argued to be the most recent astronomical analogue for the last glacial and current interglacial period. This similarity is mainly a function of orbital scale climatic changes (eccentricity, precession). To gain a better insight into the Iberian peninsular climate and its transitions during these periods, a marine sediment core from the Alboran Sea, Western Mediterranean, is used to reconstruct climate relevant variables related to surface ocean, atmospheric circulation and hydrology by applying a set of organic geochemical proxies (biomarkers). The location of the core, between the African continent and the Iberian Peninsula make it especially interesting for investigating regional climate changes and transitions in an area with significant hominid remains. Here we present millennial scale resolution data (2 ky) for the interval from 0 to 130 and 374-484 ky corresponding to MIS 1-6 and 11-12, respectively. The results of this multi-biomarker analysis give new insights into past ocean climate conditions as well as into the processes that occurred onshore during this period. The reconstruction of sea surface temperatures is done by the analysis of alkenones (UK37’-index). Chlorophyllic pigment concentration is used as proxy for paleoproductivity. Terrestrial eolian inputs and vegetation changes are determined by the analysis of n-alkyl compounds (long chain n-alkanes, n-alkenols and n-alkanoic acids) which are major components of leaf waxes from terrestrial higher plants. Like mineral aerosols, these compounds are wind-transported from terrestrial vegetation sources to adjacent oceans where the particles settle and are preserved in ocean sediments with very little diagenetic alteration. To assess hydrology related shifts in Iberian peninsular climate, the compound specific hydrogen isotope ratio in higher plant n-alkanes was used. These biomarkers offer a promising tool for reconstructing terrestrial vegetation from marine sequences and help to understand the link between climate change in the Mediterranean, its transitions and possible effects on past human evolution in this area.