文档介绍：摘要研究区处于阿尔泰山脉东段南缘,位于西伯利亚板块西南边缘、准噶尔板块的东北边缘,是西伯利亚板块和准噶尔板块斜向碰撞对接的构造部位。本文以新疆青河卫东乡变质基性岩为研究对象,通过详细野外路线调查、重点剖面测制和室内镜下薄片分析, 对该变质基性岩野外分布情况、延伸方向、规模和产状及岩石组合特征、岩相学特征进行了认真研究。同时,对样品进行了岩石地球化学分析测试和同位素年代学测试,从地球化学和同位素地质年代学方面探讨该变质基性岩的形成构造环境和形成时代,取得了以下初步认识: 通过实测剖面分析卫东乡姜巴斯套组沉积环境应为深海一次深海一浅海。(±) Ma(MSWD=),表明其形成时代为晚泥盆世一早石炭世(D3—℃1)。地球化学特征分析显示,卫东乡变质基性火山岩具有贫碱、尤其是贫钾,低Ti02 的特征,应为低钾拉斑玄武岩。其稀土分配模式为LREE弱富集型,具有较高的EREE。 MORB标准化的微量元素蛛网图呈现出大离子亲石元素(K,Sr,Rb,Ba)富集,亏损高场强元素,具Nb、Ta和Hf的负异常。这些地球化学特征表明卫东乡变质基性火山岩形成于弧后盆地环境。,从晚泥盆世开始, 由于准噶尔洋在向北面的大陆之下俯冲,形成了沿额尔齐斯一乌伦古湖俯冲带、喀拉通克岛弧带、阿舍勒一克兰弧后盆地带。因此研究区在晚泥盆一早石炭世的形成环境与整体区域上的构造环境应该是相对应的。关键词:变质基性岩;地球化学;姜巴斯套组:;弧后盆地;阿尔泰山 ABSTRACT Researched area islocated atthesouthmargin ofthe eastsectionofAltaimountain.,the southwest margin ofSiberiaplate,northeastmargin ofJunggar plate,where istheoblique collisionandjointing position of thetWo ofWeidong,Qinghe,Xinjiang is selected astheresearchobject detailedwild-,fieldgeological survey,key sectionmeasuring andindoormicroscope study,the wild—fielddistribution,scale,occurrence andassemblage andpetrology ,,thepetrogeochemistry analysis and isotopicdating ofrock samples were can discuss thetectonic environment andformationage ofmetabasites viageochemistry andisotopegeochronology. Maincognitions are acquired as follows: Thesedimentaryenvironment ofJiangbasitao formation inWeidong Country shouldbe fromdeep-sea,sub-deep sea toepeiric seabyanalysis ofthemeasured profile.. The LA··ICP-.MS zirconU·-Pbisotope age ofmetadacite ofJiangbasitao formation in Weidong shows thatthe formation age ofJiangbasitao isfrom latedevonian to earlycarboniferous(D:;_℃1). The geochemical analysis showed thatthemetabasites havethecharacteristics、)~rithpoor alkali,especially poor potassium should belowpotassium distributionmodel of rare-earthelements is weak LREE