Variability in magnesium, carbon and oxygen isotope compositions of brachiopod shells

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Hauptverfasser: Rollion-Bard, C, Saulnier, S, Vigier, N, Schumacher, A, Chaussidon, Marc, Lécuyer, Christophe
Format: Dataset Open Access
Sprache:en
Veröffentlicht: PANGAEA 2017
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author Rollion-Bard, C
Saulnier, S
Vigier, N
Schumacher, A
Chaussidon, Marc
Lécuyer, Christophe
author_facet Rollion-Bard, C
Saulnier, S
Vigier, N
Schumacher, A
Chaussidon, Marc
Lécuyer, Christophe
collection Datos científicos de ciencias marinas y ambientales
contents This study presents the carbon, oxygen, and magnesium isotope compositions of two modern brachiopods, Terebratalia transversa and Frieleia halli, and one fossil specimen (2.3 Ma), Terebratula scillae. The aim of this study is to investigate the variability of these isotopic compositions and to evaluate the potential of brachiopods as a proxy of past seawater d26Mg values. The two investigated brachiopod shells present the same range of d26Mg variation (up to 2 per mil). This variation cannot be ascribed to changes in environmental parameters (temperature or pH). As has been previously observed, the primary layer of calcite shows the largest degree of oxygen and carbon isotope disequilibrium relative to seawater. In contrast, the d26Mg value of the primary layer is comparable to that of the secondary calcite layer value. In both T. scillae and T. transversa, negative trends are observable between magnesium isotopic compositions and oxygen and carbon isotopic compositions. These trends can be explained by kinetic effects linked to changes in growth rate during the brachiopod life. The innermost calcite layer of T. transversa is in isotopic equilibrium for both oxygen and magnesium and could therefore be the best target for reconstructing past d26Mg values of seawater.
format Dataset Open Access
id pangaea_https___doi_org_10_1594_PANGAEA_873386
institution PANGAEA
language en
publishDate 2017
publisher PANGAEA
record_format pangaea
spellingShingle Variability in magnesium, carbon and oxygen isotope compositions of brachiopod shells
Rollion-Bard, C
Saulnier, S
Vigier, N
Schumacher, A
Chaussidon, Marc
Lécuyer, Christophe

This study presents the carbon, oxygen, and magnesium isotope compositions of two modern brachiopods, Terebratalia transversa and Frieleia halli, and one fossil specimen (2.3 Ma), Terebratula scillae. The aim of this study is to investigate the variability of these isotopic compositions and to evaluate the potential of brachiopods as a proxy of past seawater d26Mg values. The two investigated brachiopod shells present the same range of d26Mg variation (up to 2 per mil). This variation cannot be ascribed to changes in environmental parameters (temperature or pH). As has been previously observed, the primary layer of calcite shows the largest degree of oxygen and carbon isotope disequilibrium relative to seawater. In contrast, the d26Mg value of the primary layer is comparable to that of the secondary calcite layer value. In both T. scillae and T. transversa, negative trends are observable between magnesium isotopic compositions and oxygen and carbon isotopic compositions. These trends can be explained by kinetic effects linked to changes in growth rate during the brachiopod life. The innermost calcite layer of T. transversa is in isotopic equilibrium for both oxygen and magnesium and could therefore be the best target for reconstructing past d26Mg values of seawater.
title Variability in magnesium, carbon and oxygen isotope compositions of brachiopod shells
topic
url https://doi.org/10.1594/PANGAEA.873386