ORIGINAL Holocene Climatic Optimum centennial-scale paleoceanography in the NE Aegean (Mediterranean Sea) Maria V. Triantaphyllou 1 & Alexandra Gogou 2 & Margarita D. Dimiza 1 & Sofia Kostopoulou 1 & Constantine Parinos 2 & Grigoris Roussakis 2 & Maria Geraga 3 & Ioanna Bouloubassi 4 & Dominik Fleitmann 5 & Vassilis Zervakis 6 & Dimitris Velaoras 2 & Antonia Diamantopoulou 3 & Angeliki Sampatakaki 2 & Vassilis Lykousis 2 Received: 3 June 2015 /Accepted: 30 September 2015 # Springer-Verlag Berlin Heidelberg 2015 Abstract Combined micropaleontological and geochemical analyses of the high-sedimentation gravity core M-4G provid- ed new centennial-scale paleoceanographic data for sapropel S1 deposition in the NE Aegean Sea during the Holocene Climatic Optimum. Sapropel layer S1a (10.2–8.0 ka) was de- posited in dysoxic to oxic bottom waters characterized by a high abundance of benthic foraminiferal species tolerating surface sediment and/or pore water oxygen depletion (e.g., Chilostomella mediterranensis, Globobulimina affinis), and the presence of Uvigerina mediterranea, which thrives in oxic mesotrophic-eutrophic environments. Preservation of organic matter (OM) is inferred based on high organic carbon as well as loliolide and isololiolide contents, while the biomarker record and the abundances of eutrophic planktonic foraminifera document enhanced productivity. High inputs of terrigenous OM are attributed to north Aegean borderland riverine inputs. Both alkenone-based sea surface temperatures (SSTs) and δO 18 G. bulloides records indicate cooling at 8.2 ka (S1a) and ~7.8 ka (S1 interruption). Sapropelic layer S1b (7.7–6.4 ka) is characterized by rather oxic conditions; abun- dances of foraminiferal species tolerant to oxygen depletion are very low compared with the U. mediterranea rise. Strongly fluctuating SSTs demonstrate repeated cooling and associated dense water formation, with a major event at 7.4 ka followed by cold spells at 7.0, 6.8, and 6.5 ka. The prominent rise of the carbon preference index within the S1b layer indicates the delivery of less degraded terrestrial OM. The increase of algal biomarkers, labile OM-feeding foraminifera and eutrophic planktonic species pinpoints an enhanced in situ marine productivity, promoted by more efficient vertical con- vection due to repeated cold events. The associated contribu- tions of labile marine OM along with fresher terrestrial OM inputs after ~7.7 ka imply sources alternative/additional to the north Aegean riverine borderland sources for the influx of organic matter in the south Limnos Basin, plausibly related to the inflow of highly productive Marmara/Black Sea waters. Introduction The Aegean Sea (NE Mediterranean) is located in a transition zone between temperate and semiarid climate conditions and is characterized by its small size but complex bathymetry. Fluvial freshwater inputs are more intense in the north due to numerous large rivers draining from the Balkans and Turkey, which provide 75% of sediment influx into the north Aegean (e.g., Lykousis et al. 2002; Roussakis et al. 2004). River runoff collectively constitutes an important source of Electronic supplementary material The online version of this article (doi:10.1007/s00367-015-0426-2) contains supplementary material, which is available to authorized users. * Maria V. Triantaphyllou mtriant@geol.uoa.gr 1 Faculty of Geology and Geoenvironment, National and Kapodistrian University of Athens, 15784Panepistimioupolis, Athens, Greece 2 Hellenic Centre for Marine Research, Institute of Oceanography, 19013 Anavyssos, Attiki, Greece 3 Laboratory of Marine Geology and Physical Oceanography, Department of Geology, University of Patras, 26100, Rion-Patra, Greece 4 Laboratoire d’Océanographie et du Climat, Expérimentation et Approche Numérique, Université Pierre et Marie Curie, Paris Cedex 05, France 5 Centre for Past Climate Change, Department of Archaeology, University of Reading, Reading RG6 6AB, UK 6 Department of Marine Sciences, University of the Aegean, 81100 Mytilene-Lesvos, Greece Geo-Mar Lett DOI 10.1007/s00367-015-0426-2