Structural control over equilibrium silicon and oxygen isotopic fractionation: A first-principles density-functional theory study

Isotopic fractionation factors for oxygen and silicon in selected silicates (quartz, enstatite, forsterite, lizardite, kaolinite) have been calculated using first-principles methods. Good agreement between theory and experiment is obtained in the case of oxygen. In the case of silicon, agreement and differences with existing estimates of equilibrium fractionation factors are discussed. The relationships between silicon fractionation factors and oxygen fractionation factors, silicate polymerization degree and chemical composition is studied. The previously stated relationship with the polymerization degree of the mineral is not confirmed. Nevertheless, our calculation suggests that silicon fractionation depends on the cationic content of the mineral, in a way similar to oxygen. Oxygen fractionation properties could thus provide some insights on silicon fractionation behavior.

Source: arXiv:2609.03486v1 - http://arxiv.org/abs/2609.03486v1 PDF: https://arxiv.org/pdf/2609.03486v1 Original Link: http://arxiv.org/abs/2609.03486v1