The influence of Al on the stability region of DHMS and water transports into the Earth's interior

(1)在14 ~ 25 GPa的MgO-Al2O3-SiO2-H2O体系中，研究了富al致密水合硅酸镁D相（PhD）在900℃~ 1500℃下的稳定性。富al的PhD在地幔过渡带压力下分解为Egg相，在上、下地幔压力下随着温度升高分解为δ-AlOOH相。广阔的含铝PhD稳定区是地幔过渡带中水的重要储藏点。(2)在900℃-1500℃条件下，研究了MgO-Al2O3-FeO-SiO2-H2O （MAFSH）体系中水欠饱和（2 wt%）模拟物在15 ~ 21 GPa范围内的相关系。结果表明，在15 ~ 16.5 GPa和1050℃以下，与瓦德利石或环伍德石共存的E相至少稳定；当压力高于16.5 GPa、温度低于1100℃时，D相与环伍德石共存。(3)在本研究中，我们确定了aloh - feooh二元体系在15-25 GPa和700℃-1200℃下的相关系。x射线衍射测量表明，δ-AlOOH和ε-FeOOH在较宽的压力和温度范围内部分形成固溶体。结果表明，在1200℃和20gpa下，在不脱水和不熔化的情况下，形成了二元共晶图。我们的研究结果表明，俯冲到深部地幔的cacl2型氢氧化物在很大的组成范围内形成了固溶体。到目前为止，我已经发表了三篇论文。我们将在几个月后再处罚三篇论文。

(1) We investigated the stability of the Al-rich dense hydrous magnesium silicate Phase D (PhD) in a MgO-Al2O3-SiO2-H2O system between 14 and 25 GPa at 900℃-1,500 ℃. Al-rich PhD decomposes to Phase Egg at pressure of the mantle transition zone, whereas it decomposes to δ-AlOOH phase with a temperature increase at pressure of the uppermost lower mantle.The wide stability region of Al-bearing PhD would contribute an important storage site for water in the mantle transition zone.(2)We investigated the phase relation of a water-undersaturated (2 wt%) analog of Martian mantle in simplified MgO-Al2O3-FeO-SiO2-H2O (MAFSH) system between 15 and 21 GPa at 900℃-1500 °C . Results showed that phase E coexisting with wadsleyite or ringwoodite was at least stable at 15-16.5 GPa and below 1050 °C. Phase D coexisted with ringwoodite at pressures higher than 16.5 GPa and temperatures below 1100 °C.(3) In this study, we ascertain the phase relations in the AlOOH-FeOOH binary system at 15-25 GPa and 700℃-1200 °C. X-ray diffraction measurements of quenched samples show that δ-AlOOH and ε-FeOOH partly form solid solutions over wide pressure and temperature ranges. Our results demonstrate that a binary eutectic diagram is formed without dehydration or melting below 1200 °C at 20 GPa. Our results suggest that the CaCl2-type hydroxides subducted into the deep mantle form a solid solution over a wide composition range.Until now, I have published three papers. We will punlish three more papers a few months later.