新疆阿拉尔花岗岩MFC过程的微量元素综合效应  

COMPLEX TRACE ELEMENT EFFECTS OF THE MIXING -FRACTIONAL CRYSTALLIZATION COMPOSITE PROCESS IN THE ARAL GRANITE OF THE ALTAY MOUNTAINS,NORTHERN XINJIANG

作　　者：刘伟[1] 

机构地区：[1]中国科学院矿物资源探查研究中心

出　　处：《地质论评》1997年第5期465-475,共11页Geological Review

基　　金：中国科学院院长基金特别支持项目;中国科学院武汉分院择优支持项目;国家自然科学基金(编号49373164)

摘　　要：新疆阿拉尔花岗岩的微量元素比值相关图显示了线性样点列与幂函数曲线形式的样点列相交的复杂图型。该图型用简单混合或者单一结晶分异模型都不能解释。本文建立了混合-结晶分异复合过程的微量元素综合效应模型。模型1(D_1<D_3,D_2<D_3,D_1≠D_2或者D_1>D_3,D_2>D_3,D_1≠D_2):从初始混合线引发出幂函数曲线束形式的结晶分异线。特殊情况(D_1=D_2≠D_3)有结晶分异线简化为通过原点的直线束形式(A>0)或者与初始混合线重合(A=0)。模型2(D_1>D_3>D_2或者D_1<D_3<D_2):从初始混合线引发出双曲线形式的结晶分界线。模拟结果表明:阿拉尔岩体经历了混合-结晶分异复合过程,混合方式可能为残留作模型。在后期结晶分异过程中,所论7个微量元素的不相容性序列为:D_(Th)<D_(La)<D_Y≈D_(Nb)≈D_(Ta)<D_(Hf)<D_(Zr),该序列对同造山深熔花岗岩可能具有普遍意义。Complex patterns of intersection of linear with power function curvilinear data point arrays are observed on the ratio-ratio correlation plots of trace elements in the Aral granite, Altay Mountains, northern Xinjiang. The complex patterns cannot be resolved with either a simple mixing model or a pure fractional crystallization model. Two models for the complex trace element effects of the mixing - fractional crystallization composite process are developed in the paper. Model 1 (D1<D3,D2<D3,D1≠D2 or D1>D3,D2>D3,D1≠D2): fractional crystallization curves assume a cluster of concave-up or convex-up power function curves which start from the initial mixing line. Special case(D1=D2≠D3) : the fractional crystallization curves either are simplified into a cluster of straight lines passing through the origin (A>0) or coincide with the initial mixing line (A>0). Model 2 (D1>D3>D2 or D1<D3<D2): the fractional crystallization curves assume the form of hyperbolic curves which start from the initial mixing line. It is demonstrated through modelling that the Aral pluton experienced the mixing - fractional crystallization composite process. The mixing mode is probably described by the restite model. The incompatibility sequence of the 7 concerned trace elements is DTh<DLa<DY≈DNb≈DTa<DZr. The sequence may be generally applicable to the syntectonic anatectic granites.

关 键 词：花岗岩 微量元素 综合效应 新疆 

分 类 号：P588.121[天文地球—岩石学]