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

本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。采用多砧装置，在压力bbb10 GPa的条件下，在MgO-FeO(Fe2O3)-SiO2-H2O体系中合成含水地幔相。迄今为止，与火星地幔相关的富铁组成的含水相的稳定性尚未被探索，潜在的新相可能在这个体系中被发现。相识别和表征将使用x射线衍射，特别是分析透射电子显微镜进行。TEM检查将包括通过电子能量损失光谱（EELS）确定铁的价态，为相的晶体化学和水的掺入机制提供见解。为了确定含水相的储水能力，将采用红外光谱和直接耦合演化气分析（DEGAS）来定量水的浓度。这些数据对于了解火星现在和过去的水循环和水库存具有根本的重要性。这项研究可能为火星表面远古海洋、巨大峡谷和流出通道的形成提供解释，这些可能是由于火星曾经潮湿的内部早期释放的水造成的。

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.