掺锶磷灰石和掺钡磷灰石的高温高压稳定性研究

Apatite is one of the carrier of strontium and barium elements. It's common that natural apatite enriches strontium and barium, which lead to the extensive use of strontium-bearing apatite and barium-bearing apatite in geological researches, such as magma evolution and geochronology. Generally, geological events refer to large scale of pressure and temperature ranges. Therefore, we need to understand the stable pressure-temperature fields of strontium-bearing apatite and barium-bearing apatite. These information, however, is unknown though lots of studies on physical-chemical properties of strontium enriched apatite and barium enriched apatite have been reported. Besides, barium doping apatite is much less than strontrium doping one in natural rocks. We speculate that the terrible stability of barium doping apatite under pressure is one of the reason. Experiments are required to verify whether our speculation is true or not. The aim of this project is to constrain the stable pressure-temperature fields of strontium-bearing calcium apatite and barium-bearing calcium apatite, by using high temperature high pressure experiments.

磷灰石是锶和钡的重要载体之一，很多天然磷灰石中富有锶或者钡元素，富锶的磷灰石和富钡的磷灰石也在研究地质事件中（岩浆演化、地质定年等）得到了应用。地质事件经常涉及到温度和压力的变化，因此我们需要知道富锶的磷灰石和富钡的磷灰石的稳定温压范围，用于对地质事件经历的温压范围进行约束。我们前期的研究表明锶或者钡完全取代磷灰石的钙之后，磷灰石的温压稳定性大幅度下降，但是天然磷灰石中锶或者钡只是部分取代钙，这种部分取代对磷灰石的稳定性有何影响还不得而知。此外，钡磷灰石比锶磷灰石少见得多，其原因之一可能是少量钡的掺入就会导致磷灰石的稳定性大幅度降低，事实如何还需要实验去证实。因此本项目拟通过高温高压实验的方法确定掺锶磷灰石和掺钡磷灰石的稳定温压范围。