Allende碳质球粒陨石中某些斜长石的阴极发光现象及其产生的机理

对Allende陨石的富钙铝包裹体中的斜长石,用电子探针和扫描电镜进行阴极发光的研究。作者对三颗生长在富钙铝包裹体中无尖晶石区域内的斜长石晶体进行了详细的研究。在电子束的轰击下它们都显示出深、浅蓝色的阴极发光带。电子探针定量分析表明,在深蓝色发光带中,杂质元素Na和Mg的含量较高(约为500～1000ppm),而在浅蓝色发光带中,Na、Mg含量相对较低(约为100～500ppm),同时Na的含量与Mg的含量呈正相关。 矿物中微量杂质的存在与矿物的阴极发光之间存在着某些规律性的联系,因此矿物的阴极发光可以作为研究矿物的一种特殊标志。此外,不同微量元素的存在也可以给出某些成因信息。 本文对引起阴极发光的物理机制也进行了讨论。

CATHODOLUMINESCENCE AND ITS MECHANISM IN PLAGIOCLASE FROM THE ALLENDE CARBONACEOUS CHONDRITE

Cathodoluminescence with scanning electron microscopy and electron microprobe is applied to the study of some plagioclases in CAIs of the Allende chondrite. The author conducted a careful investigation on three plagioclase grains occurring in spinel-free island in a CAIs from Allende. All of them display two cathodoluminescence zones of distint brightness. Electron microprobe analyses of the two different luminescence domains have confirmed the previous findings that the dark blue luminescence zones are enriched in MgO and Na_2O contents (100-500 ppm). It is obvious that there exists a relationship between the special variations of cathodolumlnescence emission and the distribution of impurities within minerals. The possible physical mechanism of cathodoluminescence in anorthite is also discussed in the present paper.