新疆三塘湖盆地牛东区块晚石炭世一二叠纪火山岩特征与构造环境分析  

THE CHARACTERISTICS AND TECTONIC SETTING OF THE LATE CARBONIFEROUS-PERMIAN VOLCANIC ROCKS FROM NIUDONG AREA,SANTANGHU BASIN,EASTERN XINJIANG

作　　者：聂保锋[1,2] 于炳松[2] 李正科[3] 文川江[3] 刘永顺[1] 宋本彪[4] 

机构地区：[1]首都师范大学资源环境与旅游学院,北京100037 [2]中国地质大学地质过程与矿产资源国家重点实验室,北京100083 [3]中国石油吐哈油田公司勘探开发研究院,新疆哈密839009 [4]中国石油勘探开发研究院,北京100083

出　　处：《新疆地质》2009年第3期217-221,共5页Xinjiang Geology

基　　金：国家重点基础研究发展计划“973”项目(2005CB422103、2006CB202302)资助

摘　　要：为探讨三塘湖盆地牛东区块晚石炭世—二叠纪火山岩类型、成因特点及区域构造背景,系统研究了其岩石学和地球化学特征,结果显示,火山岩属中-基性岩类.玄武岩主要组成斑晶矿物是斜长石、辉石和少量橄榄石,为钠质碱性系列.安山岩主要组成矿物是斜长石、少量辉石,为低钾-中钾钙碱系列.火山岩稀土元素含量较高,w(EREE)在104.60×10^(-6)～203.28×10^(-6),w(LREE/HREE)比值为6.92～18.75,La_N/Yb_N比值为7.07～35.18,属轻稀土元素富集型.稀土元素分布模式为右倾曲线,无Eu负异常,δEu为0.88～1.05.δCe为0.91～1.04.火山岩富含LILE(特别是Ba,K)和LREE,强烈亏损HFSE(Nb,Ta),具很高的LREE/HREE比值.判别图解表明,研究区晚石炭世—二叠纪岩浆活动既显示板内演化特征,又有陆缘弧火山岩地球化学痕迹.综合区域地质资料和前人研究成果,推断研究区晚石炭世—二叠纪火山岩可能是弧火山岩浆在造山后期伸展裂陷环境中的喷发产物.To make a further study of rock types ,Genesis of the late Carboniferous -Permian volcanic rocks from Niudong area,Santanghu basin, eastern Xinjiang and the regional structural background,petrology and geochemistry is discussed in this paper .The main volcanic rocks are defined as basic to intermediate volcanic rocks. The main phenocrysts of the basalt are plagioclases, pyroxenes ,and olivincs, belong to the Na-rich alkaline series.The andesite is composed of plagioclases and pyroxenes,are low- K calcalkali rocks, the both volcanic rocks show LREE/HREE= 6.92-18.75, LaN/YbN= 7.07- 35.18 ,Eu--0.88-1.05, δCe =0.91-1.04.It indicate that the volcanic rocks are enriched in light rare earth element（LREE） and without remarkable Eu depletion. The trace elements are characterized by enrichment in LILE content s, intensive depletion in HFSE contents, the andesites indicate that the Santanghu area was in the active contineutalmargin, The geochemical analysis of volcanic rocks shows not only the signature of within-plate setting,but also indicating that some characteristics of subduction zone.

关 键 词：新疆 三塘湖盆地 牛东区块 火山岩系列 构造环境分析 

分 类 号：P588.14[天文地球—岩石学]