【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。更多还原

【Abstract】 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±3Ma and 322±3Ma respectively.Lithological and geochemical analysis show that two plutons belong to low-K tholeiitic 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.更多还原