清镇陨石（EH3）中陨硫钙石的REE微量元素及成因意义

本文运用INAA分析了14个清镇陨石中陨硫钙石单矿物颗粒的难熔元素(La、Ce、Sm、Eu、Yb、Lu、Ca、Sc、Hf和Th),挥发性元素(Na、Cr、Zn、Se、Br等)和亲铁元素(Fe、Ni、Co、Ir、Au、As)含量。结果表明陨硫钙石高度富集难熔亲石元素,是顽火辉石陨石中REE的主要载体,携带了约80％的全岩REE总量。相对于HREE,LREE有更大的富集程度,而且早期凝聚的颗粒较晚期凝聚的颗粒更富集REE,同时陨硫钙石富集挥发性元素Se、Br等。清镇陨硫钙石的微量元素特征揭示了它来自于太阳星云的高温凝聚特征和成因。

REE AND OTHER TRACE ELEMENT CHEMISTRY OF CaS IN QINGZHEN CHONDRITE (EH3) AND THEIR ORIGIN IMPLICATIONS

INAA of 14 single oldhamite grains extracted from the Qingzhen chondrite (EH3) for refractory (La,Ce,Sm,Eu,Yb,Lu,Ca,Sc,Hf,Th),volatile (Na,Cr,Zn,Se,Br etc.) and siderophile elements (Fe,Ni,Co,Ir,Au,As) reveals that oldhamite is highly enriched in refractory elements,acting as the principal carrier of REE and contains about 80% of all REE in the bulk rock of the Qingzhen enstatite chondrite.Furthermore,LREE has larger enrichment relative to HREE in the Qingzhen oldhamite.In general,the oldhamite form metal-sulfide as-sembleges is more enriched in REE than that from the matrix,i.e.the earlier the oldhamite grains condensed,the more they are enriched in REE.Meanwhile,it is also enriched in volatile elements such as Se,Br etc.In terms of the trace element distribution of the Qingzhen oldhamite it is a high-temperature condensate from the nebula with the solar composition and its condensate origin are suggested.