TY - JOUR
T1 - Coupled Mg/Ca and clumped isotope analyses of foraminifera provide consistent water temperatures
AU - Breitenbach, Sebastian F.M.
AU - Mleneck-Vautravers, Maryline J.
AU - Grauel, Anna Lena
AU - Lo, Li
AU - Bernasconi, Stefano M.
AU - Müller, Inigo A.
AU - Rolfe, James
AU - Gázquez, Fernando
AU - Greaves, Mervyn
AU - Hodell, David A.
PY - 2018/9/1
Y1 - 2018/9/1
N2 - The reliable determination of past seawater temperature is fundamental to paleoclimate studies. We test the robustness of two paleotemperature proxies by combining Mg/Ca and clumped isotopes (Δ47) on the same specimens of core top planktonic foraminifera. The strength of this approach is that Mg/Ca and Δ47 are measured on the same specimens of foraminifera, thereby providing two independent estimates of temperature. This replication constitutes a rigorous test of individual methods with the advantage that the same approach can be applied to fossil specimens. Aliquots for Mg/Ca and clumped analyses are treated in the same manner following a modified cleaning procedure of foraminifera for trace element and isotopic analyses. We analysed eight species of planktonic foraminifera from coretop samples over a wide range of temperatures from 2 to 29°C. We provide a new clumped isotope temperature calibrations using subaqueous cave carbonates, which is consistent with recent studies. Tandem Mg/Ca–Δ47 results follow an exponential curve as predicted by temperature calibration equations. Observed deviations from the predicted Mg/Ca-Δ47 relationship are attributed to the effects of Fe-Mn oxide coatings, contamination, or dissolution of foraminiferal tests. This coupled approach provides a high degree of confidence in temperature estimates when Mg/Ca and Δ47 yield concordant results, and can be used to infer the past δ18O of seawater (δ18Osw) for paleoclimate studies.
AB - The reliable determination of past seawater temperature is fundamental to paleoclimate studies. We test the robustness of two paleotemperature proxies by combining Mg/Ca and clumped isotopes (Δ47) on the same specimens of core top planktonic foraminifera. The strength of this approach is that Mg/Ca and Δ47 are measured on the same specimens of foraminifera, thereby providing two independent estimates of temperature. This replication constitutes a rigorous test of individual methods with the advantage that the same approach can be applied to fossil specimens. Aliquots for Mg/Ca and clumped analyses are treated in the same manner following a modified cleaning procedure of foraminifera for trace element and isotopic analyses. We analysed eight species of planktonic foraminifera from coretop samples over a wide range of temperatures from 2 to 29°C. We provide a new clumped isotope temperature calibrations using subaqueous cave carbonates, which is consistent with recent studies. Tandem Mg/Ca–Δ47 results follow an exponential curve as predicted by temperature calibration equations. Observed deviations from the predicted Mg/Ca-Δ47 relationship are attributed to the effects of Fe-Mn oxide coatings, contamination, or dissolution of foraminiferal tests. This coupled approach provides a high degree of confidence in temperature estimates when Mg/Ca and Δ47 yield concordant results, and can be used to infer the past δ18O of seawater (δ18Osw) for paleoclimate studies.
KW - Clumped isotopes
KW - Mg/Ca analysis
KW - Paleoceanography
KW - Paleoclimatology
KW - Planktonic foraminifera
UR - http://www.scopus.com/inward/record.url?scp=85045017561&partnerID=8YFLogxK
U2 - 10.1016/j.gca.2018.03.010
DO - 10.1016/j.gca.2018.03.010
M3 - Article
AN - SCOPUS:85045017561
SN - 0016-7037
VL - 236
SP - 283
EP - 296
JO - Geochimica et Cosmochimica Acta
JF - Geochimica et Cosmochimica Acta
ER -