塔里木西南缘布雅花岗岩体地球化学特征及构造意义  

Geochemistry and tectonic significance of Buya granite in southwestern margin of Tarim, NW China

作　　者：朱彦菲 李平 朱志新[1,2] 靳刘圆 刘鑫[1] 陈邦学 

机构地区：[1]新疆大学地质与矿业工程学院,乌鲁木齐830046 [2]新疆地质调查院,乌鲁木齐830011 [3]新疆地矿局第十一地质勘查大队,新疆昌吉831100

出　　处：《地质科学》2015年第3期810-823,共14页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：中国地质调查局项目“重要造山带关键地区区域地质专项调查”和“环塔里木前寒武纪成矿作用及大型找矿靶区优选研究”（编号：12120114064301,1212011140056）资助.

摘　　要：布雅花岗岩体侵位于塔里木南缘铁克里克断隆带下元古界埃连卡特岩群，其主体由二长花岗岩组成。锆石LA-ICP-MSU-Pb定年结果表明，布雅花岗岩体形成于晚奥陶世（457．03—445．07Ma），是早古生代岩浆作用的产物。岩石地球化学表明其具高钾钙碱性系列特征，岩体为准铝质I型花岗岩，并具有高Ba-sr花岗岩的岩石地球化学特征，即高Ba、sr和LREE含量，高Sr／Y、La／Yb值，低Y（5．9×10-6-8．0×10-6）、Yb（O．41×10-6-0．72×10-6）和HREE（4．01×10-6～5．02×10-6），轻重稀土元素强烈分异，无明显Eu负异常，亏损Nb、P、Ti等高场强元素。根据该岩体岩石地球化学特征及前人对高Ba-Sr花岗岩成因研究成果，笔者认为该岩体可能为岩石圈的拆沉和减薄作用引发地幔岩石圈发生部分熔融，后伴随着角闪石、黑云母和副矿物的分离结晶形成了高Ba-Sr的布雅花岗岩，其物质来源很可能与含远洋沉积物（含碳酸盐岩）俯冲板片析出流体／熔体交代的富集地幔以及早元古埃连卡特岩群基底物质所组成的混合源区有紧密联系。Buya granites emplaced into Ailiankate Group which located in Tiekelike tectonic belt of the southern margin of Tarim, which mainly consists of Monzonitic granite. Zircon LA-ICP-MS U-Pb dating results show that Buya granite formation in the Late Ordovician （457.03-445.07 Ma） and belongs to the product of Early Paleozoic magmatism. Rock geochemistry indicates that its features with high-K calc-alkaline series, with aluminum 1 -type granites, and have geochemical characteristics of high Ba-Sr granites, namely high Ba, Sr and LREE content, high Sr/Y, La/Yb values, low Y（5.9×10-6-8. 0×10-6） , Yb（0.41×10-6-0. 72×10-6 ） and HREE （4.01×10-6- 5.02×10-6 ）, LREE and HREE strongly differentiation, without significantly negative Eu anomaly, low Nb, P, Ti high field strength elements. According to the rock geochemical characteristics and high Ba-Sr granite genesis of previous research, I believe that the rock partial melting may cause by delamination and thinning of the lithosphere of mantle lithosphere, and formed Buya high Ba-Sr granites accompanied by fractional crystallization of hornblende, biotite and accessory mineral. Its source material is likely to mixed source including enriched mantle which contains ocean sediments （including carbonate rocks） subducted slab precipitate fluid/melt and substances of Early Proterozoic Ailiankate Group.

关 键 词：塔里木 铁克里克 高Ba—Sr花岗岩 布雅 新疆 

分 类 号：P588[天文地球—岩石学] P597[天文地球—地质学]