Publications des scientifiques de l'IRD

Dissard Delphine, Reichart G. J., Menkès Christophe, Mangeas Morgan, Frickenhaus S., Bijma J. (2021). Mg/Ca, Sr/Ca and stable isotopes from the planktonic foraminifera T. sacculifer : testing a multi-proxy approach for inferring paleotemperature and paleosalinity. Biogeosciences, 18 (2), p. 423-439. ISSN 1726-4170.

Titre du document
Mg/Ca, Sr/Ca and stable isotopes from the planktonic foraminifera T. sacculifer : testing a multi-proxy approach for inferring paleotemperature and paleosalinity
Année de publication
2021
Type de document
Article référencé dans le Web of Science WOS:000611534700002
Auteurs
Dissard Delphine, Reichart G. J., Menkès Christophe, Mangeas Morgan, Frickenhaus S., Bijma J.
Source
Biogeosciences, 2021, 18 (2), p. 423-439 ISSN 1726-4170
Over the last decades, sea surface temperature (SST) reconstructions based on the Mg/Ca of foraminiferal calcite have frequently been used in combination with the delta O-18 signal from the same material to provide estimates of the delta O-18 of water delta O-18, a proxy for global ice volume and sea surface salinity (SSS). However, because of error propagation from one step to the next, better calibrations are required to increase the accuracy and robustness of existing isotope and element to temperature proxy relationships. Towards that goal, we determined Mg/Ca, Sr/Ca and the oxygen isotopic composition of Trilobatus sacculifer (previously referenced as Globigerinoides sacculifer) collected from surface waters (0-10 m) along a north-south transect in the eastern basin of the tropical and subtropical Atlantic Ocean. We established a new paleotemperature calibration based on Mg/Ca and on the combination of Mg/Ca and Sr/Ca. Subsequently, a sensitivity analysis was performed in which one, two or three different equations were considered. Results indicate that foraminiferal Mg/Ca allows for an accurate reconstruction of surface water temperature. Combining equations, delta O-18 can be reconstructed with a precision of about +/- 0.5 parts per thousand. However, the best possible salinity reconstruction based on locally calibrated equations only allowed for a reconstruction with an uncertainty of +/- 2.49. This was confirmed by a Monte Carlo simulation, applied to test successive reconstructions in an "ideal case" in which explanatory variables are known. This simulation shows that from a purely statistical point of view, successive reconstructions involving Mg/Ca and delta O-18 preclude salinity reconstructions with a precision better than +/- 1.69 and hardly better than +/- 2.65 due to error propagation. Nevertheless, a direct linear fit to reconstruct salinity based on the same measured variables (Mg/Ca and delta O-18(c)) was established. This direct reconstruction of salinity led to a much better estimation of salinity (+/- 0.26) than the successive reconstructions.
Plan de classement
Limnologie physique / Océanographie physique [032] ; Limnologie biologique / Océanographie biologique [034]
Description Géographique
ATLANTIQUE ; ZONE TROPICALE
Localisation
Fonds IRD [F B010080932] ; Nouméa
Identifiant IRD
fdi:010080932
Contact