新疆南天山东段早石炭世——早二叠世花岗岩类及其对南天山洋盆闭合时间的约束  

Geological Characteristics of Middle-Late Paleozoic Granitoid Plutons in the East Section of Chinese South Tianshan and Its Constraints to the Closure Time of South Tianshan Ocean

作　　者：尼加提.阿布都逊 木合塔尔.扎日 贾晓亮[3] 

机构地区：[1]新疆大学地质与矿业工程学院,新疆乌鲁木齐830046 [2]新疆大学中亚造山带大陆动力学与成矿预测自治区重点实验室,新疆乌鲁木齐830046 [3]西北大学大陆动力学国家重点实验室,陕西西安710069

出　　处：《现代地质》2016年第2期263-273,共11页Geoscience

基　　金：国家自然科学基金项目(41502213;41562010;41162006)

摘　　要：选择南天山东段早石炭世-早二叠世典型花岗岩类,即阿訇开里得南岩体、盲起苏岩体、东泉戈壁岩体和库米什北岩体进行岩石学与地球化学对比研究.结果表明,这些岩体属于准铝质-过铝质高钾钙碱性系列花岗岩,富集Ba、Rb、Th、U等大离子亲石元素,亏损Nb、Ta、Zr、Hf等高场强元素,稀土元素配分模式呈右倾型,富集轻稀土元素、亏损重稀土元素,铕出现中等负异常（δEu=0.52～0.96）.基于上述相似特征,并结合前人研究成果,认为它们形成于陆-陆碰撞环境.基于南天山造山带东西段高压变质岩、岩浆岩、沉积岩和蛇绿混杂岩等方面的岩石成岩年龄对比,认为南天山晚古生代构造演化过程具有区域差异性,碰撞作用在其东段发生于早石炭世,而在其西段发生于晚石炭世.南天山洋东段闭合时间早于西段.Four typical granitoids exposed in east section of south Tianshan are chosen for this study.Geochemi-cal analyses show that these intrusions are metaluminous to peraluminous high-K calc-alkaline series and rela-tively rich in LILEs of Rb,Ba,Th and U,poor in HFSEs of Nb,Ta,Zr,Hf.The chondrite-normalized REE diagrams show that these intrusions are rich in LREE and depleted in HREE with high fractionations of LREE and HREE and moderate negative Eu anomalies(δEu =0.52 -0.96).Such similar geochemical and petrologi-cal characteristics and previous studies indicated that the granitoids formed during the continental collision stage.Correlation of diagenetic ages for high pressure metamorphic rocks,plutons,sedimentary formations and ophiolitic mélanges exposed in the east-west section of south Tianshan indicates regional differences during late Paleozoic tectonic evolution process of south Tianshan which can be characterized by early Carboniferous colli-sion on the eastern part and late Carboniferous collision on the western part,supporting that the closure time of the east section was earlier than the west section of the Paleo-south Tianshan ocean.

关 键 词：南天山 库鲁克塔格 花岗岩类 构造演化 闭合时间 

分 类 号：P542[天文地球—构造地质学]