Assessing the Ethmodiscus ooze problem: new perspective from a study of an eastern equatorial Atlantic core |
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| Institution: | 1. Department of Earth Sciences, Faculty of Geosciences, Utrecht University, Budapestlaan 4, 3584 CD Utrecht, The Netherlands;2. Marine Biogeosciences, Alfred Wegener Institute, Helmholtz Centre for Polar and Marine Research, Am Handelshafen 12, 27570 Bremerhaven, Germany;3. Department of Aquatic Ecology, Netherlands Institute of Ecology (NIOO-KNAW), Droevendaalsesteeg 10, 6708 PB Wageningen, The Netherlands;4. Royal Netherlands Institute for Sea Research (NIOZ), Landsdiep 4, 1797 SZ ‘t Horntje, Texel, The Netherlands;1. Centre for Marine Ecosystems Research, School of Natural Science, Edith Cowan University, 270 Joondalup Dr, Joondalup, WA 6027, Australia;2. Centre for Coastal Biogeochemistry, Southern Cross University, P. O. Box 157, Lismore, NSW 2480, Australia;1. Department of Agronomy, University of Córdoba, Campus Rabanales, Edif. da Vinci, 14071, Córdoba, Spain;2. Centro Regional de Estudios del Agua, Castilla-La Mancha University, 02071, Albacete, Spain;1. Centre for Biomaterials and Tissue Engineering (CBIT), Universitat Politècnica de València, Camino de Vera s/n, 46022 Valencia, Spain;2. Biomedical Research Networking Center in Bioengineering, Biomaterials and Nanomedicine (CIBER-BBN), Spain |
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| Abstract: | Several are the hypotheses proposed to explain the occurrence of Ethmodiscus oozes in tropical sediments representative of some glacial periods. In this paper, a review of those hypotheses within a paleoclimatic perspective is presented. Flux records of Ethmodiscus fragments found in site M16772 (1°21′ S, 11°58′ W) during the last 190 ka are compared to the other marine and freshwater diatom accumulation rates (AR) and diatom assemblages composition. Ethmodiscus is present all along the core, but Ethmodiscus-rich levels are found at 185–170 and 150–140 ka (stages 6.6 and 6.4), and at 70–60 ka (stage 4.2), levels where a concomitant increase in the flux of the other marine diatoms, and in the contribution to the assemblage of diatom species related to equatorial and coastal upwelling, and river plume waters is also observed. Climatic conditions favouring simultaneous occurrence of strong equatorial upwelling, coincident with increased advection of waters from coastal upwelling areas and important river run-off are proposed as the explanation for these Ethmodiscus-rich levels. |
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