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对西藏曲珍过铝花岗岩的地球化学研究表明,岩石中SiO_2、Al_2O_3和K_2O的含量均很高,贫TiO_2和Fe_2O_3;SiO_2变化为72．72%～73．34%,为铝和硅过饱和类型,属典型的含白云母过铝质花岗岩(MPG)。稀土元素总量(∑REE)为99．71×10~(-6)-132．85×10~(-6),稀土元素配分曲线显示铕负异常明显,具负铈异常。Nb、P、Ti等高场强元素具有明显的负异常,而La、Nd、Y等大离子亲石元素具有明显的正异常。过铝指数图、微量元素标准化蛛网图、岩石组合R_1-R_2图解、Rb-(Y+Nb)和Nb-Y图解均指示曲珍岩体是产生于同碰撞环境的花岗岩,其定位机制与板片俯冲、碰撞后陆内调整有关。Sr和Nd同位素组成具非常负的ε_(Nd)(t)值(-14．8～-15．4)和非常老的Nd模式年龄,表明其来源可能是古老的上地壳物质,而ε_(Sr)(t)-ε_(Nd)(t)图解也支持其上地壳来源。岩体具有较高~(87)Sr/~(86)Sr初始比值(0．72699～0．73884)特征,据此推断曲珍过铝花岗岩成因是陆壳部分熔融作用产物。岩浆源区可能以粘土岩为主,砂质岩占次要地位,是成熟陆块部分熔融作用的结果。
The geochemical study on the Quzhen peraluminous granite in Tibet shows that the contents of SiO_2, Al_2O_3 and K_2O in the rock are very high, the contents of TiO_2, Fe_2O_3 and SiO_2 vary from 72.72% to 73.34% Type, is a typical muscovite-bearing peraluminous granite (MPG). The total content of rare earth elements (ΣREE) is 99.71 × 10 -6 -613 × 108 × 10 -6, and the distribution curve of rare earth elements shows the negative anomalies of europium with negative cerium anomalies. High field strength elements such as Nb, P and Ti have obvious negative anomalies, whereas large ion lithophile elements such as La, Nd and Y have obvious positive anomalies. Overlaid aluminum index maps, standardized trace elements of trace elements, rock composition R_1-R_2 diagram, Rb- (Y + Nb) and Nb-Y diagram both indicate that the Quzhen pluton is granite produced in the same collision environment, Subduction, land-based adjustments after the collision. The Sr and Nd isotope compositions have very negative values of ε Nd Nd (-14.8 ~ -15.4) and very old age of Nd mode, indicating that the source rocks may be ancient upper crustal materials, whereas ε_ ( The Sr (t) -ε_ (Nd) (t) scheme also supports its upper crustal origin. The results show that the genesis of Quzhen peraluminous granite is the result of partial melting of continental crust. The magmatic source area may be mainly claystone, with sandy rock taking the secondary position, which is the result of partial melting of mature landmass.