Jurnal Internasional Komposisi Isotop Magnesium Tes Foraminifers Bentik Besar: Implikasi untuk Biomineralisasi – Maeda – – Geokimia, Geofisika, Geosystems
The composition of Mg isotopes in biogenic CaCO 3 is expected to reflect the ocean Mg cycle, but its practical application for paleoenvironmental reconstruction is complicated by the influence of sea water temperatures and biologically mediated isotope fractions. In this study, we investigate the relationship between water temperature, growth rate, and Mg isotope ratios (1945 26 Mg) of high biogenic β-Mg calcite which forms a large benthic foraminifera test. We breed large benthic foraminifers that are reproduced asexually ( Amphisorus kudakajimensis and Calcarina gaudichaudii ) at 21-30 ° C. We measure the Mg / Ca ratio, Mg chemical speciation and Calcarina gaudichaudii ) at 21-30 ° C. ] 26 Mg for both species. The Mg / Ca ratio shows a significant temperature dependence for both species, while the value of 1945 26 Mg for different populations C . gaudichaudii showed an increase in discrimination of heavy isotopes with an increase in temperature. X-ray absorption from the spectrum of near-edge structures from the foraminiferal test shows Mg speciation is consistent with inorganic calcite, indicating an ideal Mg substitution for Ca in the crystal lattice. Values δ 26 Mg for both species close to inorganic calcite and other marine organisms that deposit high calcite – Mg. These results indicate that the deposition of μM-high calcite tests for both species is similar to inorganic calcite and the fractionation of Mg isotopes for both species is only slightly affected by individual physiological processes related to growth temperature. Carb values 26 Mg carb-sol from several field samples included in the range ∆ 26 Mg carb-sol range for inorganic calcite, giving preliminary evidence that the effects of intraspecific differences in values δ 26 Mg can be averaged by careful selection of samples for analysis.