On the combination of the planktonic foraminiferal Mg/Ca, clumped (Δ 47 ) and conventional (δ 18 O) stable isotope paleothermometers in palaeoceanographic studies
International audience Assuming that foraminiferal clumped isotope (Δ 47 ) values are independent of seawater salinity and pH, the combination of Mg/Ca, δ 18 O and Δ 47 values, may in theory allow us to disentangle the temperature, salinity/δ 18 Osw and pH signals. Here, we present a new Mg/Ca-Δ 47...
Published in: | Geochimica et Cosmochimica Acta |
---|---|
Main Authors: | , , , , , , , , , , |
Other Authors: | , , , , , , , , , , , , , , , , , , , , |
Format: | Article in Journal/Newspaper |
Language: | English |
Published: |
HAL CCSD
2022
|
Subjects: | |
Online Access: | https://insu.hal.science/insu-03868225 https://doi.org/10.1016/j.gca.2022.10.030 |
Summary: | International audience Assuming that foraminiferal clumped isotope (Δ 47 ) values are independent of seawater salinity and pH, the combination of Mg/Ca, δ 18 O and Δ 47 values, may in theory allow us to disentangle the temperature, salinity/δ 18 Osw and pH signals. Here, we present a new Mg/Ca-Δ 47 dataset for modern planktonic foraminifera, from various oceanographic basins and covering a large range of temperatures (from 0.2 to 25.4 °C). These measurements were performed on the same samples and species as the ones used for the foraminiferal Δ 47 calibration of Peral et al. (2018), allowing comparison between both Mg/Ca and Δ 47 paleothermometers (excluding the two benthic foraminiferal data points). There is a good agreement between these two paleothermometers when the Mg/Ca-temperature is corrected for seawater salinity and pH, suggesting that foraminiferal Δ 47 may not be influenced by salinity or pH. However, our results show that Δ 47 temperature uncertainties still limit our ability to reconstruct pH and δ 18 O sw from the combination of Mg/Ca, δ 18 O and Δ 47 in a useful manner. We also find that disagreements between Mg/Ca and Δ 47 values in G. bulloides persist after correction for vital, salinity and pH effects, suggesting that other process(es) may also influence Mg/Ca in this species. This study also provides an updated I-CDES version of the previously published planktonic and benthic foraminiferal Δ 47 calibration of Peral et al. (2018), covering a range of temperature from -2 to 25.4 °C. |
---|