高温高压下绿辉石成因研究

Genesis Study of Omphacite at High Pressure and High Temperature

在3GPa,1 200℃条件下,分别以碱性玄武岩粉末和等化学计量光谱纯试剂为原料进行高温高压熔融结晶实验,对实验产物进行了电子探针测试和拉曼光谱分析,确定结晶产物为绿辉石,其拉曼谱峰的半高宽较窄且形态尖锐,表明绿辉石晶体中Si—O四面体结构稳定,矿物内部有序度高。结合前人研究成果探讨了绿辉石成因的影响因素及其原始岩浆,结果表明绿辉石的形成可能受母岩成分、体系流体含量和温压条件等多种因素影响。本实验结果为绿辉石和榴辉岩成因学研究提供可能的实验依据。

The melting and recrystallizing experiments of alkali basalt powder and mixture of pure oxides mixed as stoichiometry were performed at 3 GPa and 1 200 ℃. Electronic microprobe analysis and Raman spectra showed that the recrystallized prod ucts were omphacites, the FWHM （full width at half maximum） of the Raman peak was narrow and its shape was sharp, which is attributed to the stable Si--O tetrahedral structure and the high degree of order in omphacite. Based on the results of previous studies, the influencing factors of omphacite genesis and its primary magma were discussed. The results showed that the forma- tion of omphacite could be affected by many factors, such as the composition of parent rocks, the concentration of fluid in the system and the conditions of pressure and temperature. This result could support some experimental evidences on the genesis studies of omphacite and eclogite.