摘要
阴山地块是华北克拉通西部太古代基底出露最大最完整的地区。固阳地区是阴山地块最具代表性的地区,主要由中西部低级别变质的晚太古代花岗-绿岩地体和东部的高级变质杂岩地体组成。统计结果表明,无论是绿岩带,花岗岩类侵入体,还是高级别变质杂岩的原岩都形成于晚太古代末期(2562～2510Ma),形成时间上相互重叠,在～2500Ma,～2480Ma分别经历了两期变质事件,第一期为逆时针的P-T轨迹,与洋脊俯冲有关;第二期则表现顺时针的P-T轨迹,与晚期碰撞造山有关。科马提岩-科马提质玄武岩、高镁安山岩-富Nb火山岩、TTG和Sanukitoid多种具有特殊构造意义的岩石同时发育。综合已有资料获得如下启示,阴山地块在晚太古代受板块体制控制,并先后经历了洋脊俯冲和碰撞造山过程。将区域内的BIF与相关岩石联系起来考虑,得出BIF的形成与洋脊俯冲有关,BIF中的Si来源于绿岩带底部的玄武岩,Fe来源于同层位的科马提岩。
The Yinshan Block is a coherent Neoarchean basement of the Western Block in the North China Craton.The representative is at Guyang area,which composed of granite-greenstone rocks at western and high-grade metamorphic complexes at eastern.The result of statistics of zircon U-Pb age statistics show either the granite-greenstone or the protoliths of the high-grade metamorphic complexes formed at the late Neoarchean （2562 ～ 2510Ma）,and experienced two stage metamorphic event at ～ 2500Ma,～ 2480Ma respectively.The P-T path of the ～ 2.50Ga metamorphism is an anti-clockwise type,which is related with the mid-oceanic ridge subduction.There are a variety of special rocks which indicating the certain tectonic background in this area,such as：komatiite,komatiitic basalt,Nb-rich basalt,high-Mg andesite,TTGs and Sanukitoid.In conclusion,the Yinshan block is controlled by the plate tectonics,and experienced the mid-oceanic ridge subducted and collision orogeny successively.The BIFs in this are related with the mid-oceanic ridge subduction.The Si and Fe of BIFs are derived from the basalt at the bottom of greenstone belt and the komatiite,respectively.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2013年第7期2329-2339,共11页
Acta Petrologica Sinica
基金
国家重点基础研究发展计划"973"项目(2012CB416605)
国家自然科学基金项目(41202138)
博士后基金(2012M510539)联合资助
