The effect of network-formers (Si, Ti, Al and P) on ferric/ferrous ratio in silicate melts: experimental study and improvement of existing models.

岩浆系统中的地球化学过程强烈地依赖于氧逸度和硅酸盐熔体中的Fe ~（3+）/Fe ~（2+）比值。该比率可以使用可用的热力学模型在理论上预测。现有的热力学模型考虑了组成参数，但主要是网络改性阳离子（Ca，Mg，Na，K）。很少有系统的研究，使我们能够考虑到网络形成阳离子（Si，Al，Ti，P）的影响。在这个项目中，Al对硅酸盐熔体中Fe 3 +/Fe 2+比的影响将在1巴下进行实验研究。结果将结合最近以前的数据集上的Si，P和Ti对硅酸盐熔体中的Fe 3 +/Fe 2+比的影响，以提供一个一致的热力学模型准确预测熔体组合物，特别是SiO2，Al 2 O3，TiO 2和P2 O 5，对铁基熔体的Fe 3 +/Fe 2+比的影响。结果是重要的镁铁质熔体在地球上产生的和他们的分化产品（镁铁质熔体），但也为从月球或其他行星系统的玄武岩的形成和演化的解释，这不同于地球玄武岩的Al/Si比。

Geochemical processes occurring in magmatic systems depend strongly on oxygen fugacity and on the Fe3+/Fe2+ ratio in silicate melts. This ratio can be theoretically predicted using available thermodynamic models. The available thermodynamic models take compositional parameters into account, but mainly for network modifying cations (Ca, Mg, Na, K). There are few systematic studies allowing us to take the effects of network forming cations into account (Si, Al, Ti, P). In this project, the effect of Al on the Fe3+/Fe2+ ratio in silicate melts will be investigated experimentally at 1 bar. The results will be combined with recent previous datasets on the effects of Si, P und Ti on the Fe3+/Fe2+ ratio in silicate melts to provide a consistent thermodynamic model predicting accurately the effect of melt composition, in particular SiO2, Al2O3, TiO2 and P2O5, on the Fe3+/Fe2+ ratio of mafic melts. The results are of importance for mafic melts generated in the Earth and for their differentiation products (silicic melts) but also for the interpretation of the formation and evolution of basalts from the Moon or other planetary systems, which differ from Earth basalts by their Al/Si ratio.