Western Mediterranean Sea Paleothermometry Over the Last Glacial Cycle Based on the Novel RI‐OH Index

• Published in: Paleoceanography and Paleoclimatology
• Main Authors: Davtian, Nina, Ménot, Guillemette, Fagault, Yoann, Bard, Edouard
• Other Authors: Centre européen de recherche et d'enseignement des géosciences de l'environnement (CEREGE), Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE), Laboratoire de Géologie de Lyon - Terre, Planètes, Environnement (LGL-TPE), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Université Jean Monnet - Saint-Étienne (UJM)-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Evolution du climat et de l'océan, Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)-Institut de Recherche pour le Développement (IRD)-Aix Marseille Université (AMU)-Collège de France (CdF (institution))-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche pour l’Agriculture, l’Alimentation et l’Environnement (INRAE)
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2019
• Subjects: planktonic-foraminifera; surface temperature; organic-matter; interannual variability; intact polar; iberian margin; climatic variability; dialkyl glycerol tetraethers; isoprenoid tetraether lipids; membrane-lipids; glacial-interglacial transitions; sea surface temperature; western Mediterranean Sea; GDGTs; TEX86; RI-OH; [SDU.STU.CL]Sciences of the Universe [physics]/Earth Sciences/Climatology; [SDE.MCG]Environmental Sciences/Global Changes; [SDU.STU.GC]Sciences of the Universe [physics]/Earth Sciences/Geochemistry; [SDU.STU.OC]Sciences of the Universe [physics]/Earth Sciences/Oceanography; Planktonic foraminifera
• Online Access: https://hal.science/hal-02115659; https://hal.science/hal-02115659/document; https://hal.science/hal-02115659/file/2018PA003452.pdf; https://doi.org/10.1029/2018PA003452

International audience RI-OH (ring index of hydroxylated tetraethers) has recently been proposed to reconstruct paleotemperatures in middle- to low-latitude marginal seas. However, RI-OH has barely been tested in marginal seas under substantial terrigenous inputs. Here we analyze tetraether lipids in two adjacent marine cores from the Gulf of Lions. We then test for the first time the RI-OH paleothermometer from 160 to 9 ka BP in the western Mediterranean Sea. While terrigenous inputs prevent TEX86 (TetraEther indeX of tetraethers consisting of 86 carbon atoms) from behaving as a paleothermometer, RI-OH is generally consistent with other paleothermometric proxies. RI-OH also responds systematically and coherently to glacial-interglacial transitions as well as to abrupt climatic events. The average difference between RI-OH temperatures and November-May U-37(K') (C-37 ketone unsaturation ratio) temperatures is -2.0 degrees C with a standard error of 0.4 degrees C based on 249 RI-OH-U- 37(K') comparisons. This systematic difference suggests that hydroxylated tetraethers and alkenones record different temperatures, for instance, winter and/or subsurface temperatures for RI-OH. Another source of bias could be linked to the available RI-OH-temperature calibration, which clearly needs more work at the global and regional scales, notably for semienclosed basins such as the Mediterranean Sea. Nevertheless, our RI-OH-based interglacial-glacial anomalies are of 10 degrees C, a value within the high end of anomalies from previously published temperature records in the western Mediterranean Sea (from 3 to 13 degrees C). The RI-OH-based temperature anomalies also confirm the regional differences and seasonal contrasts in interglacial-glacial anomalies produced by models.