Anomalous SST warming during MIS 13 in the Gulf of Lions (northwestern Mediterranean Sea) Aleix Cortina a,⇑ , Joan O. Grimalt a , Belen Martrat a , Andrés Rigual-Hernández b , Francisco Javier Sierro c , José Abel Flores c a Department of Environmental Chemistry, IDAEA-CSIC, 08034 Barcelona, Spain b Department of Biological Sciences, Macquarie University, North Ryde, NSW 2109, Australia c Department of Geology, University of Salamanca, 37008 Salamanca, Spain article info Article history: Received 27 September 2015 Received in revised form 2 December 2015 Accepted 5 December 2015 Available online 11 December 2015 Keywords: Alkenone MIS 13 Gulf of Lions abstract During the PROMESS campaign (summer 2004) a borehole (PRGL1) was drilled in the upper slope of the Gulf of Lions covering the last 530 kyr. Here, we present new biomarker data from 440–528 kyr in order to reconstruct past climate variability, sea surface temperature (SST) (alkenone-based) and oxygenation of the bottom waters (based on n-hexacosanol and n-nonacosane ratio) during Marine Isotope Stages (MIS) 12 and 13. Contrary to southern paleorecords, MIS 13 showed the warmest SST values of the past 530 kyr in the Gulf of Lions, which is in agreement with recent findings in northern continental paleo- records. Our data suggest that the ice volume in northern latitudes and its effect on Inter-Tropical Convergence Zone (ITCZ) position during winter caused the anomalous warming in the northwestern Mediterranean during MIS 13. Moreover, the northward incursion of the ITCZ could have modified the stadial reinforcement of north-westerly winds documented from MIS 11 to the present. Ó 2015 Elsevier Ltd. All rights reserved. 1. Introduction The MIS 13 has been the subject of recent studies due to the dis- agreement between southern and northern paleorecord recon- structions. Compared with the later interglacials, benthic d 18 O values of MIS 13 (478–533 kyr) (Lisiecki and Raymo, 2005) showed the heaviest values, which are usually interpreted as a signal of lar- ger global ice volume. This view is in agreement with the Epica Dome C dD (EDC dD) records, where MIS 13 yielded the coolest interglacial temperatures of the 800 kyr (about 4 °C cooler than the Holocene; Jouzel et al., 2007). However, several continental records of the Northern Hemisphere contradict the idea of a cooler interglacial having a larger ice volume. For example, analysis of sediment cores from: (1) the Loess deposits in China (Vandenberghe, 2000; Sun et al., 2006; Guo et al., 2009), lower and middle Danube River (Fitzsimmons et al., 2012) and Serbia (Markovic ´ et al., 2009); (2) Greenland coast (de Vernal and Hillaire-Marcel, 2008) and (3) lakes of the Tibetan plateau (Chen et al., 1999) and Siberia (Prokopenko et al., 2002) suggest that the conditions during MIS 13 were relatively warm and coupled with relatively low global ice volume. The intensity of the north-westerly winds in the Gulf of Lions has been suggested to be influenced by the extension of the ice- sheets in the Northern Hemisphere (Kuhlemann et al., 2008; Cortina et al., 2011, 2013). The presence of large ice-sheets during Last Glacial Maximum (LGM) resulted in the southward displace- ment of the position of the polar front (Pflaumann et al., 2003) causing the invasion of Arctic air masses into the northwestern Mediterranean with a consequent decrease of sea surface temper- atures (SST) in the Gulf of Lions (Kuhlemann et al., 2008). There- fore, the study of SST variations in the Gulf of Lions could be a good indicator of the northern ice-sheet variability. Here, we pre- sent new biomarker data from MIS 12 to MIS 13 of the core PRGL1 situated in the Gulf of Lions with the main goal to investigate the northern ice-sheet extension during MIS 13 and to provide new insights into the paleoclimatic conditions during this interglacial stage. 2. Study area As part of the European Project PROMESS 1 (profiles across Mediterranean Sedimentary Systems), borehole PRGL1 (300 m http://dx.doi.org/10.1016/j.orggeochem.2015.12.004 0146-6380/Ó 2015 Elsevier Ltd. All rights reserved. ⇑ Corresponding author. E-mail address: acortina@usal.es (A. Cortina). Organic Geochemistry 92 (2016) 16–23 Contents lists available at ScienceDirect Organic Geochemistry journal homepage: www.elsevier.com/locate/orggeochem