Mg isotope fractionation during calcite precipitation: An experimental study
| Type | : | ACL |
|---|---|---|
| Nature | : | Production scientifique |
| Au bénéfice du Laboratoire | : | Non |
| Statut de publication | : | Publié |
| Année de publication | : | 2012 |
| Auteurs (4) | : | SAULNIER S ROLLION-BARD C VIGIER Nathalie CHAUSSIDON M |
| Revue scientifique | : | Geochimica et Cosmochimica Acta |
| Volume | : | 91 |
| Fascicule | : | |
| Pages | : | 75-91 |
| DOI | : | 10.1016/j.gca.2012.05.024 |
| URL | : | <go to isi>://wos:000307120800006 |
| Abstract | : | Experimental precipitations of calcite and other carbonate minerals were performed under various conditions of pH, temperature and solution Mg/Ca to determine the Mg partition coefficient and Mg isotope fractionation. Fifteen experiments were performed at pH ranging from 7.41 +/- 0.07 to 8.51 +/- 0.39, temperature ranging from 16.2 +/- 0.7 to 26.5 +/- 0.3 degrees C and Mg/Ca-solution ranging from 0.11 to 0.52 mol/mol. The apparent Mg partition coefficient between calcite and solution (D-Mg) spans a large range of values from 0.018 +/- 0.014 to 0.15 +/- 0.11 and carbonate Mg isotope fractionation (Delta Mg-26) ranges from -2.53 +/- 0.25 parts per thousand to -1.33 +/- 0.14 parts per thousand and does not correlate with either pH or temperature. The range in D-Mg and Delta Mg-26 suggests non-equilibrium partitioning controlled by the processes of calcite growth, i.e. mixing between calcite grown at equilibrium and fluid inclusions, and entrapment of a surface Mg-rich calcite layer in isotopic equilibrium with the solution. The equilibrium Mg isotope fractionation between inorganic calcite and solution is estimated to be -2.13 +/- 0.24 parts per thousand. Additional Mg elemental and isotopic fractionations are observed to occur during biogenic formation of calcite due to variable removal of Mg by the organisms (high-Mg calcite corals, foraminifera) of seawater Mg from their calcification medium. (C) 2012 Elsevier Ltd. All rights reserved. |
| Mots-clés | : | - |
| Commentaire | : | Times Cited: 12 13 |
| Tags | : | - |
| Fichier attaché | : | - |
| Citation | : |
Saulnier S, Rollion-Bard C, Vigier N, Chaussidon M (2012) Mg isotope fractionation during calcite precipitation: An experimental study. Geochim Cosmochim Ac 91: 75-91 | doi: 10.1016/j.gca.2012.05.024
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