摘要
查干花钼矿床是内蒙古中西部的一个大型斑岩钼矿床。矿床成矿期花岗岩为似斑状黑云母花岗岩。2个花岗岩样品锆石SHRIMP U-Pb定年结果分别为253.3±2.8Ma(MSWD=1.17)和253.8±3.7Ma(MSWD=1.6),显示成矿期花岗岩形成于253～254Ma,为晚二叠世。与前人辉钼矿Re-Os测年研究(～243Ma)对比显示,矿床的成岩成矿时间差约为10Ma,这与矿床控矿构造及成矿期花岗岩的结构构造特征相符,也与国内外较多的斑岩型矿床成岩可以对比,反映出查干花钼矿床是成矿岩体经历了长时间演化以后岩浆-热液体系的产物。元素地球化学研究显示,成矿期花岗岩具有高硅、高碱、准铝质至过铝质和高钾钙碱性的特征。其源区是受到早期陆缘弧俯冲作用改造及地壳混染的岩石,再经过部分熔融作用所形成。其微量元素继承了早期陆缘弧成因岩石的一些特征。岩浆在形成以后,在深部岩浆房内经历了以斜长石和钾长石为主导的分离结晶作用,并在上侵到地壳浅部区域以后受到了远古宇宝音图群的混染。其形成的构造环境为古生代末期向中生代转换的后碰撞环境。
Located in central-west Inner Mongolia,China,Chaganhua porphyry molybdenum is a newly discovered large scale deposit.Geochronological and elemental data are presented for the ore-forming granites.The data show that the ore-forming granite was emplaced and crystallized in the Late Permian（253～254Ma） .Compared with the molybdenite Re-Os dating（243Ma） from literature,it indicate that the Chaganhua molybdenum deposit was formed about 10Ma after the ore-forming granite was emplaced,which reflects a magmatic-hydrothermal ore forming system after long lived evolution and differentiation of the ore-forming granite.The major elements data show these granites are high K calc-alkaline series,metaluminous-peraluminous and characteristic of high silicon,high alkali.Combined with the trace elements features,it indicates that the ore-forming magmas is most plausibly originated by partial melting of previous subduction modified source,and has inherited some features of subduction related magma.The ore-forming magmas has undergone plagioclase and potash feldspar dominated crystal fractionation process before transported to the ore forming structure and were contaminated by the Baoyintu gneiss.The forming of these granites and Chaganhua deposit were favored by the post-collision regime as the chemical features show.
出处
《岩石学报》
SCIE
EI
CAS
CSCD
北大核心
2012年第2期409-420,共12页
Acta Petrologica Sinica
基金
国家重点自然科学基金项目(41030421)
基本业务费项目(K1012)
地质大调查项目(1212010911029)联合资助
关键词
斑岩钼矿床
高钾钙碱性
花岗岩
元素地球化学
查干花
狼山造山带
Porphyry molybdenum deposit
High K calc-alkaline
Granites
Elements geochemistry
Chaganhua
Langshan orogen
