新疆中天山科克苏地区高钾钙碱性花岗岩地球化学特征、成因及形成环境

High-Potassic Calc-Alkaline Granitoids from Kekesu Area in Central Tianshan,Xinjiang:Petrogenesis,Geochemical and Tectonic Setting

以新疆中天山科克苏地区高钾钙碱性花岗岩为研究对象,分析该花岗岩全岩主微量元素及Sr-Nd同位素,发现该花岗岩具高Si,Na,K,Al,低Fe,P,Ti,Mg^#特征;富集Rb等大离子亲石元素（LILE）元素,亏损Nb,Ti等高场强（HFS）元素;主量元素（Fe,Mg,Ca,P,Ti）及部分微量元素（Ba,Sr）多与Si O2呈负相关。地球化学特征表明,科克苏地区高钾钙碱性花岗岩岩浆经历了结晶分异过程。该花岗岩εNd（T）为负值,Mg^#,Ce,Pb,U,Nb等指示岩浆来源为地壳物质的部分熔融。Rb,Y,Nb,Ta等揭示该高钾钙碱性花岗岩形成于后碰撞环境。

The granitoids from Kekesu area in central Tianshan Xinjiang belong to the high-potassic calc-alkaline series and exhibit high Si、Na、K、Al and low Fe、P、Ti、Mg^#characteristics. These granitoids are all enriched in Rb and depleted in Nb、Ti and have lower εNd（T） values. Most of the major elements（such as Fe、Mg、Ca、P、Ti） and some trace elements（such as Ba、Sr） show a negative correlstion with Si O2,indicating that the granitoids from Kekesu area underwent the fractional crystallization. The value of εNd（T） is negative,besides the element of Mg^#、Ce、Pb、U、Nb which could indicate the source of granitoids all show the graitoids from Kekeu area come from the crust（including metaigneous or igenous）,so the source of granitoids is crust partial melting. Those elements,such as Rb、Y、Nb、Ta,indicate the granitoids formed in post-collision setting.