Late Pliocene vegetation and orbital-scale climate changes from the western Mediterranean area

Abstract

The Late Pliocene is a very interesting period as climate deteriorated from a warm optimum at ca. 3.3–3.0Ma to a progressive climate cooling. Simultaneously, the Mediterranean area witnessed the establishment of the Mediterranean-type seasonal precipitation rhythm (summer drought). These important climate changes produced significant vegetation changes, such as the extinction of several thermophilous and hygrophilous plant taxa from the European latitudes. Besides these long-term trends, climate was also characterized by cyclical variability (i.e., orbital changes) that forced vegetation changes (forested vs. open vegetation). In the Mediterranean area, cyclical changes in the vegetation were mostly forced by precession. In this study we analyzed pollen from a Late Pliocene maar lake core from NE Spain. An increase in aridity is observed as well as cyclic variations throughout the studied sequence. Cyclicity was mostly forced by precession but also by obliquity and eccentricity. Precipitation seems to be the main factor controlling these cycles. These data allowed estimating a sedimentary rate of ca. 0.19mm/yr and the time duration covered by the studied core, close to 200ka. The combination of biostratigraphy, palaeomagnetism and cyclostratigraphy allowed for a very precise dating of the sediments between ca. 3.3 and 3.1Ma. Climate and paleobiogeographical implications are discussed within the context of the Late Pliocene Northern Hemisphere glacial intensification.