西秦岭温泉岩浆混合花岗岩的地球化学特征

西秦岭温泉岩体是壳、幔岩浆混合的产物。寄主岩石(酸性端元)属铝过饱和钙碱性系列,贫CaO富FeOtotal,ANKC值大于1 1,NK/A均小于0 9,富Mo、Sn、Bi、W等高温热液成矿元素及Co、Ni、Cr等亲铁元素,LREE/HREE为10～15。基性端元暗色微细粒镁铁质包体及基性岩墙,富Na2O、K2O,而贫FeOtotal,异常富集轻稀土和Ba、Rb、Sr、Zr、Th、Hf、Nb等大离子亲石元素,而贫Co、Ni、Cr等亲铁元素,LREE/HREE为9 98～13 5,异常富轻稀土。由2端元岩浆混合形成的岩浆混合花岗岩,地球化学特征介于2端元间,并有显著的过渡特征和依从关系,反映了重要的岩浆混合信息。

THE GEOCHEMICAL FEATURES OF THE WENQUAN MAGMA-MINGLING GRANITE IN WESTERN QINLING

The Wenquan magma-mingling granite in western Qinling is the mingling product from magmas of crust and mantle. The host rocks belong to the aluminium-supersaturation and calc-alkali series, and are characterized as being poor in CaO,rich in FeO(total) and high-temperature hydrothermal metallogenic elements such as Mo, Sn and Cr. Petrochemical analysis indicates that the ANKC value is over 1.1, the NK/A ratio is less than 0.9,and the LREE/HREE ratio is between 10 and 15. In the mafic enclaves and basic veins , Na2O and K2O are richer and FeO(total) is poorer, and, the light REE and larger-ion lithophile elements such as Ba,Rb,Sr,Zr,Th,Hf and Nb are extremely rich, the siderophile elements are also poorer and the LREE/HREE ratio is between 9.98 and 13.5. The abnormal distribution of the trace elements indicates the noticeably exchanging and complying between the two end-members, and the intensively mingling granite shows the markable transition between crust and mantle.