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 δ^49/47Ti (δ^49/47Ti = [(⁴⁹Ti/⁴⁷Ti)_sample/(⁴⁹Ti/⁴⁷Ti)_OL-Ti] × 1000) range (− 0.036 ± 0.043‰ to 0.082 ± 0.021 ‰), and no correlation between δ^49/47Ti and the degree of differentiation is observed. By contrast, Fe-Ti oxide saturated group samples show a remarkable δ^49/47Ti variation, ranging from 0.005 ± 0.018‰ to 1.914 ± 0.006 ‰, which are positively correlated with SiO₂ contents, and negatively correlated with MgO contents. In particular, multiple SiO₂ vs. δ^49/47Ti trends are observed in Fe-Ti oxide saturated group, which are controlled by crystal fractionation degrees, magma SiO₂ compositions, and Fe-Ti oxide compositions during magma differentiation. [ABSTRACT FROM AUTHOR]