内蒙古西乌旗南部石炭纪石英闪长岩地球化学特征及其构造意义  

Geochemical Characteristic of Carboniferous Quartz-Diorite in the Southern Xiwuqi Area,Inner Mongolia and Its Tectonic Significance

作　　者：刘建峰[1] 迟效国[1] 张兴洲[1] 马志红[1] 赵芝[1] 王铁夫[2] 胡兆初[3] 赵秀羽[1] 

机构地区：[1]吉林大学地球科学学院,长春130061 [2]吉林大学测试科学实验中心,长春130026 [3]中国地质大学地质过程与矿产资源国家重点实验室,武汉430074

出　　处：《地质学报》2009年第3期365-376,共12页Acta Geologica Sinica

基　　金：国家油气专项"大庆探区外围中新生代断陷盆地群演化与油气远景"(编号XQ-2007-07);"中国东北地区油气勘探新领域基础地质研究"(编号GO800-06);国家自然科学基金""兴蒙海槽"晚古生代构造演化"(编号40739905)资助的成果

摘　　要：内蒙古西乌旗地区位于贺根山蛇缘岩带和西拉木伦缝合带之间,区内岩浆岩分布广泛。本文对达其浑迪和金星石英闪长岩进行了锆石LA-ICP-MSU-Pb定年,结果表明两个岩体分别形成于325±3Ma和322±3Ma。岩石学和地球化学分析结果显示岩石属于低钾拉斑系列和钙碱性系列,相对富集Rb、Ba、K等大离子亲石元素(LILE),亏损Nb、Ta、Ti、P等高场强元素化学。地球化学成分表明岩体具有俯冲带成因的特征。通过区域对比分析,苏左旗和西乌旗地区均发育一套角闪闪长岩、石英闪长岩、英云闪长岩及花岗闪长岩组合,与岛弧和活动大陆边缘岩浆岩组合相似,共同构成早石炭世晚期到晚石炭世的岩浆弧,该岩浆弧的出现与古亚洲洋板片向北俯冲有关。The Xiwuqi area of Inner Mongolia is tectonically situated at the suture zone between Hegenshan and Xar Moron faults. Magmatic rocks occur widely in the area. LA-ICP-MS dating for zircon separated from the Daqinhundi and Jinxing quartz-diorite plutons indicates that both plutons formed at 325-t-3Ma and 322 -l-3Ma respectively. Lithological and geochemical analysis show that two plutons belong to low-K tholeiitie and calk-alkaline series, and are enriched in large ion lithophile elements （LILE） such as Rb, Ba and K, and depleted in high field strength elements （HFSE） such as Nb, Ta, Ti and P. Geochemical compositions also show that the plutons are characterized by subduction genesis. Combined with regional data, a suite consisting of hornblende diorite, quartz-diorite, tonalite and granodiorite is developed in the Suzuoqi and Xiwuqi areas and similar to the complex in island arc and active continental margin. This set of rocks form early and late Carbonifous magmatic arc, presence of which may be related to the northward subduction of paleo-Asian ocean slab.

关 键 词：西乌旗 石英闪长岩 地球化学 晚石炭世 古亚洲洋 

分 类 号：P597.3[天文地球—地球化学]