Surface and subsurface seawater temperature reconstruction using Mg/Ca microanalysis of planktonic foraminifera Globigerinoides ruber , Globigerinoides sacculifer , and Pulleniatina obliquiloculata

• Published in: Paleoceanography
• Main Authors: Sadekov, Aleksey, Eggins, Stephen, de Deckker, Patrick, Ninnemann, Ulysses, Kuhnt, Wolfgang, Bassinot, Franck
• Other Authors: Research School of Earth Sciences ANU, Canberra (RSES), ANU College of Science Canberra, Australian National University (ANU)-Australian National University (ANU), Department of Earth Science Bergen (UiB), University of Bergen (UiB), Institut für Geowissenschaften Kiel, Christian-Albrechts-Universität zu Kiel = Christian-Albrechts University of Kiel = Université Christian-Albrechts de Kiel (CAU), Laboratoire des Sciences du Climat et de l'Environnement Gif-sur-Yvette (LSCE), Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA)), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA), Paléocéanographie (PALEOCEAN), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université de Versailles Saint-Quentin-en-Yvelines (UVSQ)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Direction de Recherche Fondamentale (CEA) (DRF (CEA))
• Format: Article in Journal/Newspaper
• Language: English
• Published: HAL CCSD 2009
• Subjects: [SDU.OCEAN]Sciences of the Universe [physics]/Ocean; Atmosphere; [SDU.ENVI]Sciences of the Universe [physics]/Continental interfaces; environment; Planktonic foraminifera
• Online Access: https://hal.science/hal-02921364; https://hal.science/hal-02921364/document; https://hal.science/hal-02921364/file/2008PA001664.pdf; https://doi.org/10.1029/2008PA001664

International audience [1] Laser-ablation inductively coupled plasma-mass spectrometry microanalyses of Mg/Ca across individual final chambers of three planktonic foraminifera species, Globigerinoides ruber, G. sacculifer, and Pulleniatina obliquiloculata, reveal significant interspecies differences in test Mg concentrations. Whereas these three species have similar Mg/Ca values at low sea surface temperatures ($22°C), they diverge markedly at high sea surface temperatures ($29°C). Explanations for these differences in species Mg/Ca values based on detailed comparison of species intratest Mg/Ca distributions suggest that compositional variability within tests cannot account for the observed deviation of species Mg/Ca values in warm-water equatorial regions. Multiple regression modeling and d 18 O analysis of Globigerinoides sacculifer tests indicate that interspecies differences in Mg/Ca values result from different depth habitats. The average Mg/Ca values of G. ruber final chambers reflect the temperature of the surface mixed layer (0-25 m), whereas those of G. sacculifer and Pulleniatina obliquiloculata correlate best with subsurface temperatures at 50-75 m and 100-125 m water depths, respectively. Mg/Ca calibration to the temperatures at these depths reveals a similar temperature control on Mg test composition in all species. Combining our results with Mg/Ca values from published culturing experiments, we derive a generalized equation for the effect of temperature and seawater salinity on foraminiferal Mg/Ca. We also show that the Mg/Ca composition of specific calcite layers within foraminiferal tests, including the low-Mg/Ca layers of Globigerinoides ruber and G. sacculifer and the cortex layer of Pulleniatina obliquiloculata, correlates with seawater temperature and can be used as an additional proxy for seawater temperature. Citation: Sadekov, A., S. M. Eggins, P. De Deckker, U. Ninnemann, W. Kuhnt, and F. Bassinot (2009), Surface and subsurface seawater temperature reconstruction using Mg/Ca ...