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在中国大陆科学钻探主孔榴辉岩中发现了重晶石。重晶石以包裹体形式保存在石榴子石中,多为浑圆状,表面积平均约250μm2。通过电子探针测试,重晶石中SrO含量大多超过20%,为锶重晶石,其化学分子式为(Ba0.4836~0.6180Sr0.3787~0.4722Ca0.0064~0.0889)S0.9688~0.9963O4。同时还发现榴辉岩中的石榴子石有柯石英假象,温压条件计算表明该榴辉岩的峰期温压条件为696~730℃,2.9~3.2GPa。电子探针成分测定包裹这些重晶石的石榴子石为峰期变质矿物,这进一步说明重晶石也经历过超高压变质。重晶石通常形成于强氧化和高盐度流体作用的条件下,本文的研究表明超高压变质过程中至少出现了一定范围内的强氧化环境和高盐度流体作用,但其地球动力学意义有待进一步研究。
Barite was found in the eclogite of the main scientific drills in mainland China. Barite in the form of inclusions stored in garnet, mostly rounded, with an average surface area of about 250μm2. Through the electronic probe test, the content of SrO in barite is mostly more than 20%, which is strontium barite whose chemical formula is (Ba0.4836 ~ 0.6180Sr0.3787 ~ 0.4722Ca0.0064 ~ 0.0889) S0.9688 ~ 0.9963O4 . At the same time, it was also found that the garnet in the eclogite has the coesite artifact. The calculation of the temperature and pressure shows that the peak temperature and pressure of the eclogite are 696 ~ 730 ℃ and 2.9 ~ 3.2GPa. The electron probe composition determination of the garnet containing these barites is a peak metamorphic mineral, further illustrating that barite also undergoes ultra-high pressure metamorphism. Barite is usually formed under the action of strong oxidation and high salinity fluid. The research in this paper shows that at least some strong oxidizing environments and high salinity fluids appear in the process of UHP metamorphism, but its geodynamic significance For further study.