递增变质作用过程中化学元素的演化规律———以山西五台群变质同位地层为例

GEOCHEMICAL EVOLUTION OF METAMORPHIC STRATOHORIZONS IN WUTAI GROUP DURING PROGRESSIVE METAMORPHISM,SHANXI PROVINCE

山西五台群文溪组和柏枝岩组岩石学特征和岩石化学、微量元素及稀土元素特征研究表明，这两个组中相应层位地球化学特征基本一致。递增变质作用使岩石贫Ｎａ２Ｏ、Ｋ２Ｏ及大离子亲石元素和相对富集ＦｅＯ、ＭｇＯ及铁族元素。由于变质作用仅使稀土元素总量发生微小变化，而不改变其总体分布型式。

A study on the rocks of Wenxi and Baizhiyan Formations in Wutai Group through petrology, petrochemistry, trace elements and REE geochemistry shows that the correspondent stratohorizons in the formations have roughly the same geochemical characteristics. Due to progressive metamorphism highly metamorphic rocks are poor in Na 2O, K 2O, large ion lithphile elements and rich in FeO, MgO and siderophile elements. Although a small change occured on the total content of REE due to the metamorphism, REE chondrite normalized distribution patterns of the stratohorizons had always no changing. According to the study, REE is an excellent indicator to the forming and evolution process of the rocks.