δ18O and Mg/Ca thermometry in planktonic foraminifera: a multi-proxy approach towards tracing coastal upwelling dynamics

DOI

Planktonic foraminifera δ18O and Mg/Ca ratios are widely considered as a powerful proxy to reconstruct past seawater-column temperature in coastal upwelling regions. Due to the complexity in the interpretation of planktonic foraminifera δ18O data with respect to past seawater temperatures, temperature determination based on the foraminifera shell Mg/Ca ratio is believed to be more accurate. However, scarce Mg/Ca calibration data exists for coastal upwelling regions, resulting in incoherent results of past seawater reconstructions. The current study along the NW Iberia coastal upwelling system intends to define the best Mg/Ca temperature equation for the most representative species of this region (Neogloboquadrina incompta, Globigerina bulloides and Globorotalia inflata). Seawater temperature from δ18O and Mg/Ca of these three planktonic foraminifera species were compared with the surface sediments alkenone derived SST, and with the in-situ temperatures measured at the depths where these foraminifera species currently live and calcify. The equations that better reflect each species calcification depth were selected as our regional equations for δ18O and Mg/Ca temperature reconstructions. The δ18O estimated temperatures for surface sediment specimens were comparable with in-situ seawater-column temperature measurements, whereas the Mg/Ca derived temperatures seem to underestimate in-situ values, in special for G. bulloides from samples affected by stronger coastal upwelling. The G. bulloides δ18O and Mg/Ca estimated temperatures from samples located offshore, further from coastal upwelling influence, are comparable to surface sediment alkenone derived temperatures. Our study shows that in upwelling areas, regional calibration of planktonic foraminifera Mg/Ca temperature equations is necessary for reliable interpretations of high-resolution past temperature variability in these important environments.

Supplement to: Salgueiro, Emilia; Voelker, Antje H L; Martin, Pamela A; Rodrigues, Teresa; Zúñiga, D; Froján, María; de la Granda, Francisco; Villacieros-Robineau, Nicolás; Alonso-Perez, F; Alberto, Ana; Rebotim, Andreia; González-Álvarez, Raquel; Castro, Carmen G; Abrantes, Fatima F (accepted): δ¹⁸O and Mg/Ca Thermometry in Planktonic Foraminifera: A Multiproxy Approach Toward Tracing Coastal Upwelling Dynamics. Paleoceanography and Paleoclimatology, 35(2)

Identifier
DOI https://doi.org/10.1594/PANGAEA.910309
Related Identifier https://doi.org/10.1029/2019PA003726
Metadata Access https://ws.pangaea.de/oai/provider?verb=GetRecord&metadataPrefix=datacite4&identifier=oai:pangaea.de:doi:10.1594/PANGAEA.910309
Provenance
Creator Salgueiro, Emilia ORCID logo; Voelker, Antje H L ORCID logo; Martin, Pamela A; Rodrigues, Teresa ORCID logo; Zúñiga, D ORCID logo; Froján, María; de la Granda, Francisco; Villacieros-Robineau, Nicolás ORCID logo; Alonso-Perez, F; Alberto, Ana ORCID logo; Rebotim, Andreia ORCID logo; González-Álvarez, Raquel ORCID logo; Castro, Carmen G (ORCID: 0000-0001-7415-078X); Abrantes, Fatima F ORCID logo
Publisher PANGAEA
Publication Year 2019
Rights Creative Commons Attribution 4.0 International; https://creativecommons.org/licenses/by/4.0/
OpenAccess true
Representation
Resource Type Supplementary Publication Series of Datasets; Collection
Format application/zip
Size 7 datasets
Discipline Earth System Research
Spatial Coverage (-10.189W, 41.551S, -8.980E, 42.919N)
Temporal Coverage Begin 2006-08-22T06:14:00Z
Temporal Coverage End 2012-09-10T00:00:00Z