摘要
团结峰地区新发现的基性-超基性岩与E-MORB、硅质岩共同组成蛇绿岩残片,基性-超基性岩为碱性系列岩石。稀土元素球粒陨石分布模式由超基性岩平坦型逐渐过渡到基性岩轻稀土富集的右倾型,无明显Eu异常,δEu为0.97~1.14,(La/Yb)_N为1.18~11.23,轻重稀土分异明显。微量元素K,Rb,Ba,Th,Ta,Nb富集,MORB标准化微量元素蛛网图与大陆板内碱性玄武岩分布形态相似,可能形成于初始洋壳陆内裂谷环境。基性-超基性岩可能起源于具E-MORB性质的软流圈地幔,岩浆上升过程中经轻微地壳混染。基性岩形成年龄为228~251 Ma,陆内裂解时间为晚二叠世晚期至中三叠世晚期。团结峰地区蛇绿岩形成时代、物质组分及分布位置可与西兰乌金蛇绿混杂岩带对比,乔尔天山-岔路口断裂可能是西兰乌金蛇绿混杂岩带的西延部分,该推断对研究昆仑山构造演化具重要意义。
Relict fragments of ophiolite are newly found in Tuanjiefeng Area of West Kunlun Mountain,consisting three suites called basic-ultrabasic rocks,E-MORB and Siliceous Rocks respectively.Among them,basic-ultrabasic rock are alkaline series rocks.Chondrite assigned pattern of rare earth elements ranges in tape from the flat type of ultrabasic rocks to the right type of light rare earth enrichment of basic rocks.As a result, Eu and（La/Yb）N are normal,which are 0.97-1.14 and 1.18-11.23 respectively,the fraction-ation between HREE and LREE is not obvious. Trace elements K,Rb,Ba,Th,Ta,Nb are obviously enriched and Cobweb diagram of trace elements of MORB standard is similar to distribution of alkaline basalt in continental intraplate,forming in stage of intracontinental rift in initial oceanic crust.Basic-ultrabasic rocks may originate from asthenospheric mantle with E-MORB nature,experiencing a slight crustal contamination in the process of magma ascent.The basic rock age is 228-251 Ma,and the intra continental cleavage can be traced back to the late Late Permian,and extended to the late middle three Triassic.The contrast in Formation age,material composition and distribution position of ophiolite between in Tuanjiefeng Area and Xilan Wujin can infer that Qiaoer Tianshan-Chalukou fault may be the part of the Xilanwujin ophiolite melange zone,which has a great significance to the study of the tectonic evolution of Kunlun Mountain.
作者
魏永峰
肖渊甫
冯昌荣
罗巍
林美英
冯邦国
Wei Yongfeng;Xiao Yuanfu;Feng Changrong;Luo Wei;Lin Meiying;Feng Bangguo(College of Earth Sciences,Chengdu University of Technology,Chengdu 610059 China;Geology Exploring andDistrict Surveying Team,Shuangliu,Sichuan,610213,China;No.2 Geological party,Xingjiang Bureau of Geology andMineral Exploration and Development,Kashgar,Xinjiang,844000,China)
出处
《新疆地质》
CAS
CSCD
北大核心
2018年第2期202-208,共7页
Xinjiang Geology
基金
昆仑-阿尔金成矿带地质矿产调查(1212011220646)项目资助
