A mid-late Holocene sapropelic sediment unit from the southern Marmara sea shelf and its palaeoceanographic significance |
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| Institution: | 1. Institute of Marine Sciences and Management, Istanbul University, Mü?küle Sokak, 34470 Vefa, Istanbul, Turkey;2. Mining Faculty, Istanbul Technical University, Maslak, Istanbul, Turkey;3. Department of Geosciences, University of Arizona, Tucson AZ85721, USA;4. Marmara Research Centre, TÜB?TAK, Gebze, Istanbul, Turkey;1. Lamont-Doherty Earth Observatory of Columbia University, Palisades, NY, USA;2. Aix Marseille University, CNRS, IRD, INRA, Coll France, CEREGE, Aix-en-Provence, France;3. IFREMER, Marine Geosciences Unit, Plouzané, France;4. ATGEO, Aix-en-Provence, France;5. ?stanbul Teknik Üniversitesi, Maden Fakültesi, Jeoloji Bölümü, Ayaza?a, 34469 ?stanbul, Turkey;6. Dokuz Eylül University, Izmir, Turkey;1. CNR - National Research Council of Italy, ISMAR - Marine Sciences Institute, Castello 2737/f, 30122 Venice, Italy;2. Italian National Agency for New Technologies, Energy and Sustainable Economic Development, Rome, Italy;3. Open Access Center for Marine Research, Klaip?da University, H. Manto 84, 92294 Klaip?da, Lithuania;1. State Key Laboratory of Organic Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Wushan, Guangzhou 510640, PR China;2. University of Chinese Academy of Sciences, Yuquan Road, Beijing 100049, PR China;1. Ghent University, Laboratory for Chemical Technology, Technologiepark 914, 9052 Ghent, Belgium;2. Lund University, Department of Chemistry, Centre for Analysis and Synthesis, 22100 Lund, Sweden;3. Ghent University, Department of Plant Systems Biology, VIB, Technologiepark 927, 9052 Ghent, Belgium;4. Ghent University, Department of Biosystems Engineering, Coupure Links 653, 9000 Ghent, Belgium;5. Unité Amélioration, Génétique et Physiologie Forestières, INRA Orléans, BP 20619, Ardon, 45166 Olivet, France;1. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA 91125, USA;2. Geology and Planetary Science, University of Pittsburgh, Pittsburgh, PA 15260, USA;3. Department of Earth Sciences, University of California, Riverside, CA 92521, USA |
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| Abstract: | A sapropelic layer, having an age of ca 4750 and 3500 14C y BP, was discovered at 0.90–2.35 m below the sea floor (mbsf) in gravity cores from the southern shelf of the Marmara Sea. It is a 15–50 cm thick, phosphorescent green to grey, plastic, clayey hemipelagic mud horizon, containing 1.5–2.9% organic carbon (Corg). The increase in Corg and biogenic carbonate, together with a rich planktonic foraminiferal fauna, indicate increased organic productivity and warm surface waters during the deposition of the sapropelic layer. The down-core profiles of Mn, Fe, Cu, Zn, Pb, Cr, Ni and Co suggest that the sapropelic layer was deposited through an essentially oxic water column. The benthonic foraminiferal fauna indicates reduced oxygen levels in bottomwaters. The sapropelic unit was deposited during a high stand of global sea level. Its deposition was initiated by a large input of terrestrial organic matter and nutrient-rich fresh waters under a relatively warm and wet climate. The fresh water supply caused a strong water stratification, which, in turn, together with high organic matter input, resulted in reduced oxygen levels in the bottomwaters. |
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