吉林省延边卧龙地区青龙村群地球化学特征

青龙村群分布于华北板块北缘东段,岩石类型主要为片麻岩类,少量片岩类、斜长角闪岩类.变质作用由角闪岩相退变为绿片岩相.其原岩为钙碱性安山岩和流纹岩组合.岩石地球化学特征表明:青龙村群所属构造环境为岛弧区,岩浆同源,并经过岛弧区玄武质岩浆的分异作用,而玄武质岩浆产生与富集型MORB地幔经历中等程度部分熔融有关,Ti相对于Zr弱亏损可能与岛弧区俯冲深度有限有关.这表明青龙村群是华北板块北缘古亚洲洋俯冲消减的结果,并且与周围岩群没有可比性.

Geochemical characteristics of Qinglongcun Group in Wolong area, Yanbian

The Qinglongcun Group is located at the eastern part of the north of North China Plate. It consists mainly of schist, gneiss and amphibolite. The group underwent the degraded metamorphism from amphibolite to greenschist facies. Its parental rocks belong to an assemblage of calc-alkaline andesite and rhyolite. Geochemical characteristics of the group indicate an island arc setting. The magma of same derivation experienced differentiation of basaltic magma in island arc, and this basaltic magma was formed by moderate degree of partial melting of the enriched MORB. That Ti depletion related to Zr and Y is probably linked with the depth of subduction of the island arc. The result shows that the Qinglongcun Group can not be correlated to the surrounding groups and may represent subduction of the Paleo-Asian Ocean underneath the northern margin of the North China Plate.