Titanium isotopic fractionation during magmatic differentiation

To better investigate the behavior of titanium (Ti) isotopes during magmatic processes, we report high-precision Ti isotope compositions for 60 terrestrial igneous rocks from different geological settings worldwide. Based on their major element compositions and petrographic descriptions, these samples can be subdivided into two groups: Fe-Ti oxide unsaturated and Fe-Ti oxide saturated. The Fe-Ti oxide unsaturated group samples show a narrow delta Ti-49/47 (delta Ti-49/47 = [(Ti-49/Ti-47)(sample)/(Ti-49/Ti-47)(OL-Ti)] x 1000) range (- 0.036 +/- 0.043 parts per thousand to 0.082 +/- 0.021 parts per thousand), and no correlation between delta Ti-49/47 and the degree of differentiation is observed. By contrast, Fe-Ti oxide saturated group samples show a remarkable delta Ti-49/47 variation, ranging from 0.005 +/- 0.018 parts per thousand to 1.914 +/- 0.006 parts per thousand, which are positively correlated with SiO(2)contents, and negatively correlated with MgO contents. In particular, multiple SiO(2)vs. delta Ti-49/47 trends are observed in Fe-Ti oxide saturated group, which are controlled by crystal fractionation degrees, magma SiO(2)compositions, and Fe-Ti oxide compositions during magma differentiation.