The Mg/Ca–temperature relationship in brachiopod shells: calibrating a potential palaeoseasonality proxy

Butler, S., Bailey, T. R., Lear, C. H., Curry, G. B., Cherns, L. and McDonald, I. (2015) The Mg/Ca–temperature relationship in brachiopod shells: calibrating a potential palaeoseasonality proxy. Chemical Geology, 397, pp. 106-117. (doi: 10.1016/j.chemgeo.2015.01.009)

Abstract

Brachiopods are long-lived, long-ranging, extant organisms, of which some groups precipitate a relatively diagenetically stable low magnesium calcite shell. Previous work has suggested that the incorporation of Mg into brachiopod calcite may be controlled by temperature (Brand et al., 2013). Here we build upon this work by using laser ablation sampling to define the intra-shell variations in two modern brachiopod species,Terebratulina retusa (Linnaeus, 1758) and Liothyrella neozelanica (Thomson, 1918). We studied three T. retusa shells collected live from the Firth of Lorne, Scotland, which witnessed annual temperature variations on the order of 7 °C, in addition to four L. neozelanica shells, which were dredged from a water depth transect (168–1488 m) off the north coast of New Zealand. The comparison of intra-shell Mg/Ca profiles with shell δ¹⁸O confirms a temperature control on brachiopod Mg/Ca and supports the use of brachiopod Mg/Ca as a palaeoseasonality indicator. Our preliminary temperature calibrations are Mg/Ca = 1.76 ± 0.27 e^{(0.16 ± 0.03)T}, R² = 0.75, for T. retusa and Mg/Ca = 0.49 ± 1.27 e^{(0.2 ± 0.11)T}, R² = 0.32, for L. neozelanica (errors are 95% confidence intervals).

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Curry, Professor Gordon
• Authors: Butler, S., Bailey, T. R., Lear, C. H., Curry, G. B., Cherns, L., and McDonald, I.
• College/School: College of Science and Engineering > School of Geographical and Earth Sciences
• Journal Name: Chemical Geology
• Publisher: Elsevier B.V.
• ISSN: 0009-2541
• ISSN (Online): 1872-6836
• Copyright Holders: Copyright © 2015 The Authors
• First Published: First published in Chemical Geology 397:106-117
• Publisher Policy: Reproduced under a Creative Commons License