高温高压条件下磷灰石在沉积物体系中的稳定性及其对全球磷循环的深部启示

全球磷循环是地球生物圈最重要的营养元素循环系统之一，但是目前的全球磷循环基本上只是关注于表层生物圈。全球磷循环在地球深部的过程和模式还没有得到充分的研究。磷灰石是地球上最普遍的含磷矿物，而沉积物体系是生物圈中最大的磷储库。本申请项目拟以磷灰石-陆源沉积物、磷灰石-远洋沉积物、磷灰石-全球俯冲沉积物这三个体系作为研究对象，在1～10GPa和800～1500 K的压力和温度条件下，采用高温高压实验装置（活塞-圆筒装置、六面顶装置）开展系统的高温高压实验研究，利用X射线衍射仪、拉曼光谱仪、电子探针、扫描电镜等进行物相、物质成份、结构形态等方面的分析测试，详细研究磷灰石在沉积物体系中的稳定性，揭示磷在沉积物硅酸盐矿物中的含量及其分配随压力和温度的变化规律，探讨全球磷循环在地球深部的行为特征和模式。

The global phosphorus cycle is one of the most important nutritive element systems in the biosphere. However, reported studies mostly focus on the surface and shallow parts of the biosphere. There is little information about the global phosphorus cycle in the deep Earth. It is known that apatite is the most common P-bearing mineral in the Earth and sediment is the largest inventory for phosphorus in the biosphere. In this proposal high-pressure and high-temperature experiments will be carried out on three systems including apatite-terrigenous sediment, apatite-pelagic sediment, and apatite-global subducted sediment, respectively. By using piston-cylinder apparatus and six-axis high-pressure press, the pressure and temperature ranges are from 1 to 10 GPa and 800 to 1500 K, respectively. The experimental products will be characterized and analyzed by X-ray diffraction, Raman spectroscopy, electron microprobe and scanning electron microscope to identify the phases and their chemical compositions and structural morphology. The stability of apatite in the three sedimentary systems will be determined. The P2O5 contents and partitionings in silicate minerals and their changes with experimental conditions (pressure and temperature) will be clarified. Based on the results, the model for global phosphorus cycle in the deep Earth will be discussed.