Stability and structures of hydrous minerals in the transition zone of the Martian mantle

该研究项目旨在研究火星地幔过渡带含水矿物的稳定性和结构。在MgO-FeO（Fe_2O_3）-SiO_2-H_2O体系中，利用多砧装置，在> 10 GPa的压力下合成了含水地幔相。与火星地幔有关的富含铁成分的含水相的稳定性迄今尚未被探索，在这个系统中可能会发现新的相。将使用X射线衍射，特别是分析透射电子显微镜进行相鉴定和表征。TEM检查将涉及通过电子能量损失谱（EELS）确定铁的价态，从而深入了解相的晶体化学和水的掺入机制。为了确定含水相的水储存能力，将通过红外光谱和直接耦合的逸出气体分析（DEGAS）对水浓度进行定量。这些数据对于了解火星现在和过去的水循环和水存量至关重要。这项研究可能会解释火星表面古老海洋的形成，以及巨大的峡谷和外流通道，这可能是由于曾经潮湿的火星内部早期释放的水。

This research project is aimed at studying the stability and structures of hydrous minerals in the transition zone of the Martian mantle. Hydrous mantle phases will be synthesized in the MgO-FeO(Fe2O3)-SiO2-H2O system at pressures > 10 GPa, using the multi-anvil apparatus. The stability of hydrous phases with iron-rich compositions relevant to the Martian mantle has so far not been explored and potentially new phases could be discovered in this system. Phase identification and characterization will be performed using X-ray diffraction and, in particular, analytical transmission electron microscopy. The TEM examination will involve the determination of the valence state of iron by electron energy-loss spectroscopy (EELS), providing insights into the crystal chemistry of phases and incorporation mechanism of water. To determine the water storage capacity of hydrous phases, the water concentrations will be quantified by IR spectroscopy and directly coupled evolved gas analysis (DEGAS). These data are of fundamental importance for understanding the present and past water cycle and water inventory of Mars. The study may provide explanations for the formation of an ancient ocean, and huge canyons and outflow channels on the surface of Mars that are possibly due to early release of water from a once wet Martian interior.