滇西梁河—潞西地区新生代英安岩的源区及成因——来自地球化学的证据

The source and origin of Cenozoic dacites in Lianghe-Luxi area,western Yunnan Province: geochemical evidence

报道了滇西梁河—潞西地区新生代英安岩的主量、微量、稀土元素和Nd同位素地球化学研究成果。英安岩富集轻稀土元素、大离子亲石元素(Rb、Th、U、K),相对亏损重稀土元素和Nb、Ta、Sr、P、Ti,具有Eu负异常和Pb正异常。火山岩的εNd(0)为-10.3^-8.72,Nd同位素模式年龄(tDM)为1.2~1.4Ga。这些地球化学特征表明,研究区英安岩源于区域基底岩系的部分熔融,并与该地区同期幔源玄武质岩浆发生了不同程度的混合。

Major elements,trace elements,REE and Nd isotopic geochemistry of the Cenozoic dacites from Lianghe-Luxi area,western Yunnan Province,were studied in this paper,and the results show that the dacites are enriched in light REE,large-ion lithophile elements and Pb and depleted in Nb,Ta,Sr,P,Ti and heavy REE,with negative Eu anomaly and positive Pb anomaly.These rocks have εNd（0） values from-10.3 to-8.72 and Nd isotopic model ages（tDM） from1.2 to 1.4Ga.It is suggested that the Lianghe-Luxi Cenozoic dacites were derived dominantly by partial melting of crystalline basement rock mixed in different degrees with melts of coeval mantle-derived basaltic magma.