|Strong kinetic effects on Sr/Ca ratios in the calcitic bivalve Pecten maximus|
|Lorrain, A.; Gillikin, D.P.; Paulet, Y.-M.; Chauvaud, L.; Le Mercier, A.; Navez, J.; André, L. (2005). Strong kinetic effects on Sr/Ca ratios in the calcitic bivalve Pecten maximus. Geology 33(12): 965-968. dx.doi.org/10.1130/G22048.1|
|In: Geology. Geological Society of America: Boulder. ISSN 0091-7613, more|
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Although Sr/Ca ratios in abiogenic calcite are strongly controlled by precipitation rates, such a kinetic effect has never been demonstrated in calcitic bivalve shells. Therefore, we report Sr/Ca ratios together with daily growth rates in the calcitic shells of four individuals of the bivalve Pecten maximus (age class I). Ratios of Sr/Ca were found to be variable among individuals that grew at the same location, illustrating that vital effects dominate over environmental controls. Although daily growth rate was correlated with shell Sr/Ca ratios, it explained only half of the Sr/Ca variations. However, daily shell surface area increment, an estimation of the total quantity of carbonate precipitated for a given time, explained 74% of the Sr/Ca variability in the shells of P. maximus. This proves, for the first time in a calcitic bivalve, that shell Sr/Ca partitioning is mainly controlled by kinetic effects. The Sr/Ca ratio should therefore be tested as a potential proxy of calcification rate in modern or fossil calcitic biocarbonates.