石榴石中磷固溶度的高温高压实验研究

The storage and migration of phosphorus in the deep Earth is an important part of the global phosphorus cycle. Garnet, the silicate mineral with the largest phosphorus accommodating capacity, is an ideal carrier for phosphorus in the mantle. Previous studies reported the content of P2O5 in a large number of natural and experimental garnets, but these results are basically in the case of unsaturated phosphorus and do not represent the solubility (maximum content) of phosphorus in garnets. In this proposal, the solubility of P2O5 in garnets will be systematically investigated in different P2O5-garnet systems under high-pressure and high-temperature conditions. The Kawai-type apparatus will be adopted to carry out experiments at conditions of 3-20 GPa and 1000-1800 K. The effects of temperature, pressure, and chemical composition on the solubility of phosphorus in the garnet will be revealed, and the storage and transport of phosphorus in the garnet will be clarified, to further explore the behavior and mode of global phosphorus cycle in the deep Earth.

磷在地球深部的储存和运移是全球磷循环的重要组成部分。石榴石是容纳磷能力最强的固相硅酸盐矿物，是地幔中磷的理想载体。前人分析了大量天然和实验石榴石样品中P2O5的含量，但基本都是磷不饱和情况下的结果，不能代表磷在石榴石中的固溶度（最大含量）。本申请项目拟以P2O5-石榴石体系为研究对象，利用Kawai型高温高压实验装置在3～20 GPa和1000～1800 K的压力和温度条件下开展实验工作，系统地研究高温高压条件下不同化学成分石榴石中P2O5的固溶度，揭示磷在石榴石中的固溶度随着成分、温度和压力的变化规律，阐明上地幔硅酸盐矿物石榴石中磷的储存和运移，进而探讨全球磷循环的深部特征和模式。

磷在地球深部的储存和运移是全球磷循环的重要组成部分。石榴子石是容纳磷能力最强的固相硅酸盐矿物，是上地幔中磷的理想载体。本申请项目以P2O5-石榴子石（镁铝榴石、铁铝榴石、锰铝榴石、钙铝榴石钙铁榴石）体系为实验初始物，利用Kawai型高温高压实验装置在3～20 GPa和1000～1800 K的压力和温度条件下研究了不同石榴石端元组分中P2O5的固溶度。揭示了磷在石榴石中的固溶度随着成分、温度和压力的变化规律，阐明上地幔硅酸盐矿物石榴石中磷的储存和运移，进而探讨全球磷循环的深部特征和模式。针对P2O5-镁铝榴石体系高温高压实验部分产物中出现的Al2SiO5、Mg3(PO4)2和Mg2P2O7相，开展了Al2SiO5多型（矽线石、红柱石、蓝晶石）的高温拉曼光谱测试及其热力学性质研究、Mg3(PO4)2多型（I、II、III相）及α-和β-Mg2P2O7相的高温X射线衍射和拉曼光谱研究，探讨了其热膨胀性及振动特性。