【摘要】 纳日贡玛一带的始新世—渐新世斑岩体多以不规则小岩株形式产出,由二长花岗斑岩组成;岩石化学类型为亚碱性的富钾钙碱性系列,SiO2、Al2O3、K2O、Na2O、LREE,Sr、Rb、Ba、Th、Ce、Mo、Cu、Au、Ag含量高,CaO、TiO2、HREE、Y、Yb、Cr、Sc、Co、Ni亏损。稀土分馏明显,Eu异常不明显。斑岩源岩为壳源,有洋壳物质的混染;其形成模式为陆内俯冲导致软流圈上涌,并向下地壳注入诱发下地壳物质熔融产生岩浆。更多还原

【Abstract】 The Eocene Oligocene ore-bearing porphyry occurs as irregular stocks in the Narigongma region,Qinghai.The porphyry is composed of monzonitic granite porphyry in the subalkaline K-rich calc-alkaline series,and characterized by higher contents of SiO2,Al2O3,K2O,Na2O,LREE and Sr,Rb,Ba,Th,Ce,Mo,Cu,Au and Ag,depletion in CaO,TiO2,HREE,Y,Yb,Cr,Sc,Co and Ni,and well-balanced the element Eu.The geochemical signatures shows that the porphyry may be derived from the continental crust contaminated by the oceanic crust,and initiated from the magmas created by the melting of the lower crust due to the upwelling of the rheosphere triggered by intracontinental subduction.更多还原