Mg/Ca-Temperature Calibration of Polar Benthic foraminifera species for reconstruction of bottom water temperatures on the Antarctic shelf


Contact
Gerhard.Kuhn [ at ] awi.de

Abstract

Benthic foraminifera Mg/Ca is a well-established bottom water temperature (BWT) proxy used in paleoclimate studies. The relationship between Mg/Ca and BWT for numerous species has been determined using core-top and culturing studies. However, the scarcity of calcareous microfossils in Antarctic shelf sediments and poorly defined calibrations at low temperatures has limited the use of the foraminiferal Mg/Ca paleothermometer in ice proximal Antarctic sediments. Here we present paired ocean temperature and modern benthic foraminifera Mg/Ca data for three species, Trifarina angulosa, Bulimina aculeata, and Globocassidulina subglobosa, but with a particular focus on Trifarina angulosa. The core-top data from several Antarctic sectors span a BWT range of −1.7 to +1.2 °C and constrain the relationship between Mg/Ca and cold temperatures. We compare our results to published lower-latitude core-top data for species in the same or related genera, and in the case of Trifarina angulosa, produce a regional calibration. The resulting regional equation for Trifarina angulosa is Temperature (°C) = (Mg/Ca −1.14 ± 0.035)/0.069 ± 0.033). Addition of our Trifarina angulosa data to the previously published Uvigerina spp. dataset provides an alternative global calibration, although some data points appear to be offset from this relationship and are discussed. Mg-temperature relationships for Bulimina aculeata and Globocassidulina subglobosa are also combined with previously published data to produce calibration equations of Temperature (°C) = (Mg/Ca-1.04 ± 0.07)/0.099 ± 0.01 and Temperature (°C) = (Mg/Ca-0.99 ± 0.03)/0.087 ± 0.01, respectively. These refined calibrations highlight the potential utility of benthic foraminifera Mg/Ca-paleothermometry for reconstructing past BWT in Antarctic margin settings.



Item Type
Article
Authors
Divisions
Primary Division
Programs
Primary Topic
Peer revision
ISI/Scopus peer-reviewed
Publication Status
Published
Eprint ID
52557
DOI 10.1016/j.gca.2020.05.027

Cite as
Mawbey, E. M. , Hendry, K. R. , Greaves, M. J. , Hillenbrand, C. D. , Kuhn, G. , Spencer-Jones, C. L. , McClymont, E. L. , Vadman, K. J. , Shevenell, A. E. , Jernas, P. E. and Smith, J. A. (2020): Mg/Ca-Temperature Calibration of Polar Benthic foraminifera species for reconstruction of bottom water temperatures on the Antarctic shelf , Geochimica et Cosmochimica Acta, 283 , pp. 54-66 . doi: 10.1016/j.gca.2020.05.027


Share


Citation

Research Platforms

Campaigns


Actions
Edit Item Edit Item