Early Pleistocene climate changes in the central Mediterranean region as inferred from integrated pollen and planktonic foraminiferal stable isotope analyses Sébastien Joannin a, ⁎ , Frédéric Quillévéré a , Jean-Pierre Suc a , Christophe Lécuyer a,b , François Martineau a a Université de Lyon; Université Lyon 1; CNRS, UMR 5125, Paléoenvironnements et Paléobiosphère, Villeurbanne,F-69622, France b Institut Universitaire de France, 103 bld Saint-Michel, 75005 Paris, France Received 9 February 2006 Available online 16 January 2007 Abstract Vegetation inherited from a Pliocene subtropical climate evolved through obliquity oscillations and global cooling leading to modern conditions. An integrated, highly time-resolved record of pollen and stable isotopes (δ 18 O and δ 13 C of Globigerina bulloides) was obtained to understand vegetation responses to Early Pleistocene climate changes. Continental and marine responses are compared in the Central Mediterranean region with a particular consideration of environmental changes during anoxic events. Pollen data illustrate vegetation dynamics as follows: [1] development of mesothermic elements (warm and humid conditions); [2] expansion of mid- and high-altitude elements (cooler but still humid conditions); and [3] strengthening of steppe and herb elements (cooler and dry conditions). These successions correlate with precession. δ 18 O variations recorded by Globigerina bulloides define two cycles (MIS 43-40) related to obliquity. At northern low- to mid-latitudes, the pollen signal records temperature and wetness changes related to precession even during global climate changes induced by obliquity. This may result in unexpected increasing wetness during glacial periods, which has to be considered specific to the Central and Eastern Mediterranean region. Lastly, an analysis of anoxic events reveals that enhanced runoff is indicated by increasing frequency of the riparian trees Liquidambar and Zelkova. © 2006 University of Washington. All rights reserved. Keywords: Pollen analysis; Stable isotopes; Climatic cycle; Early Pleistocene; Central Mediterranean region; Crotone Introduction Pleistocene climates were characterized by the alternation of glacial and interglacial periods driven by the expansion and retreat of continental ice sheets over northern latitudes (e.g., Ruddiman, 2003; Berger and Loutre, 2004). It is well established that these alternations were controlled by the astronomical cycles of eccentricity, obliquity and precession (e.g., Milankovitch, 1941; Hays et al., 1976). These orbit- related alternations have been the focus of intensive studies in deep-sea sediments, providing abundant information on the evolution of Pleistocene marine-related climate (e.g., Ruddiman et al., 1989). For the Middle and Late Pleistocene, spectral analyses on foraminiferal oxygen isotope records have suggested that eccentricity was the dominant parameter controlling glacial–interglacial changes (Imbrie et al., 1993; Ashkenazy and Tziperman, 2004), whereas obliquity was the dominant forcing parameter during the Early Pleistocene (Pisias and Moore, 1981; Kroon et al., 1998; Ruddiman, 2003). Recent debates nevertheless suggest that the 100,000 yr glacial– interglacial cycles that characterize the Middle and Late Pleistocene may be more closely linked to precessional forcing, being limited by each fourth or fifth precessional cycle (Ruddiman, 2003; Maslin and Ridgwell, 2005). Pollen records obtained from the Mediterranean region have provided a framework to identify climatically-related vegetation Quaternary Research 67 (2007) 264 – 274 www.elsevier.com/locate/yqres ⁎ Corresponding author. Université de Lyon, Lyon, F-69003, France. Fax: +33 472 44 83 82. E-mail address: sebastien.joannin@univ-lyon1.fr (S. Joannin). 0033-5894/$ - see front matter © 2006 University of Washington. All rights reserved. doi:10.1016/j.yqres.2006.11.001