磷灰石单晶体同步辐射X射线荧光探针成分分析

Analysis of Apatite Crystals by Synchrotron Radiation X-ray Fluorescence Microprobe

采用同步辐射X荧光(SRXRF)探针技术对河北峪耳崖和甘肃大水两地花岗岩中单颗粒磷灰石的化学成分进行了分析。结果显示,磷灰石含有P、Cl、S、K、Ca、Mn、Fe、La、Ce、Nd、Sm、Gd、Yb、Sr、Y、Zr、U、Th等多种元素,峪耳崖磷灰石富含Mn、Fe,大水磷灰石则富含As。峪耳崖花岗岩为S型,大水花岗岩为I型,两地磷灰石在稀土元素(REE)含量上具有明显差别:大水磷灰石呈右倾的REE配分模式和明显的轻稀土(LREE)富集;而峪耳崖呈现上凸的REE配分模式和LREE亏损。依据磷灰石的REE配分模式可有效地区分不同类型的花岗岩,以此作为花岗岩岩浆演化的指示。

Synchrotron radiation X-ray fluorescence （SRXRF） microprobe was used in chemical component analysis of single granule apatite crystal from Yu＇erya, Hebei province and Dashui district, Gansu province. The result shows that apatites contain many elements including P, Cl, S, K, Ca, Mn, Fe, La, Ce, Nd, Sm, Gd, Yb, Sr, Y, Zr, U and Th and show different characteristics for their origins. Apatites from Yu＇ erya granite contain higher Mn and Fe, but lower As than those from Dashui. Apatites from these two districts have a great difference in rare earth element （REE） contents. Dashui apatites, I-type granite, show right-inclined pattern with strong LREE enrichment. Yu＇ erya apatites, S-type granite, show upward-convex chondrite patterns with pronounced depletion of LREE. The results have important implications for identifying different types of granite. And apatite chemistry can be used as an excellent indicator for granite petrogenesis study.