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

Mawbey, Elaine M.; Hendry, Katharine H.; Greaves, Mervyn J.; Hillenbrand, Claus-Dieter; Kuhn, Gerhard; Spencer-Jones, Charlotte L.; McClymont, Erin L.; Vadman, Kara J.; Shevenell, Amelia E.; Jernas, Patrycja E.; Smith, James A.

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


Authors

Elaine M. Mawbey

Katharine H. Hendry

Mervyn J. Greaves

Claus-Dieter Hillenbrand

Gerhard Kuhn

Charlotte L. Spencer-Jones

Kara J. Vadman

Amelia E. Shevenell

Patrycja E. Jernas

James A. Smith



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 and 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, although further work is required before they are routinely used.

Citation

Mawbey, E. M., Hendry, K. H., Greaves, M. J., Hillenbrand, C., Kuhn, G., Spencer-Jones, C. L., …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, 54-66. https://doi.org/10.1016/j.gca.2020.05.027

Journal Article Type Article
Acceptance Date May 23, 2020
Online Publication Date Jun 4, 2020
Publication Date 2020-08
Deposit Date Jun 7, 2020
Publicly Available Date Mar 29, 2024
Journal Geochimica et Cosmochimica Acta
Print ISSN 0016-7037
Publisher Meteoritical Society
Peer Reviewed Peer Reviewed
Volume 283
Pages 54-66
DOI https://doi.org/10.1016/j.gca.2020.05.027

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