南天山东段白土滩二叠纪花岗质杂岩体锆石定年、地球化学及构造意义  

Zircon Geochronology and Geochemical Characteristics and Tectonic Significance of Permian Granitic Complex at Baitutan,Southern Tianshan

作　　者：芮婷[1] 陈淑娥[1] 樊双虎[1] 苏春乾[1] 职荣军[1] 刘明[1] 王江伟[1] 毛友亮 

机构地区：[1]长安大学地球科学与资源学院,陕西西安710054

出　　处：《新疆地质》2014年第1期42-47,共6页Xinjiang Geology

基　　金：中国地质调查局项目(1212011120465)资助

摘　　要：白土滩花岗质杂岩体主要由黑云二长花岗岩、正长花岗岩和花岗闪长岩构成。通过锆石LA-ICP-MS U-Pb法测得黑云二长花岗岩和正长花岗岩的年龄分别为(291±2)Ma和(277±3)Ma。岩石地球化学研究表明,与黑云二长花岗岩相比,花岗闪长岩中硅、碱较低,而铝较高;高∑REE和∑LREE,低铕负异常;富Cr,Zn,Sr,Zr,Ba和Hf,贫Rb,Ta和Th,Nb/Ta和Zr/Hf均升高,DI,Rb/Sr下降,从花岗闪长岩到黑云二长花岗岩表现出连续分异演化的趋势。结合区域地质特征认为,白土滩花岗质杂岩体为高钾钙碱性I型花岗岩,其源区物质是含水的、碱性和高钾钙碱性的安山岩和玄武质安山岩,形成于南天山东段碰撞造山的碰撞-后碰撞阶段。The Baitutan granitic complex is mainly composed of monzogranites,orthoclase granites and granodiorites. Zircon LA-ICP-MS U-Pb dating gave ages of (291±2) Ma and (277±3) Ma for the monzogranite and orthoclase granite. Geochemically,in comparison with the monzogranite, the granodiorite is lower in Si,alkai,DI,Eu,Rb,Ta,Th and Rb/Sr,but higher in ∑REE,∑LREE,Nb/Ta and Zr/Hf, and richer in Cr, Zn, Sr, Zr, Ba and Hf. A continuous differentiation ternd is exhibited from granodiorite to monzogranite. Based on geological setting and geochemical characteristics, it is showed that Baitutan granitic complex is high-K calc-alkaline 1 I-type granites, the source material is aqueous, alkaline and high-K calc-alkaline andesite and basaltic andesite. It is produced in a trsnsitional tectonic setting from continental collision tectonic environment of orogenic epoch to post-collisonal.

关 键 词：白土滩 锆石LA-ICP-MS定年 高钾钙碱性I型花岗岩 构造环境 

分 类 号：P588.121[天文地球—岩石学] P597.3[天文地球—地质学]