华北地块北缘西段巴音诺尔公—狼山地区牙马图岩体的岩浆混合成因——岩相学和元素地球化学证据  

Magma Mixing Origin of Yamatu Granite in Nuoergong—Langshan Area,Western Part of the Northern Margin of North China Craton: Petrological and Geochemical Evidences

作　　者：张建军[1,2] 王涛[2] 张招崇[1] 童英[2] 张磊[2] 史兴俊[1,2] 郭磊[2] 李舢[2] 曾涛[2] 

机构地区：[1]中国地质大学,北京100083 [2]中国地质科学院地质研究所,北京100037

出　　处：《地质论评》2012年第1期53-66,共14页Geological Review

基　　金：973项目(编号2001CB409800;2007CB411307);中国地质调查局资助项目(编号1212010611803;1212010611817;1212010811033);国家自然科学基金资助项目(编号40702010)的成果

摘　　要：华北地块北缘西段巴音诺尔公—狼山地区的牙马图岩体以二长花岗岩为主,岩体中广泛发育岩浆暗色包体,二者界线明显。包体为岩浆结构,大多数具有塑性外形,发育淬冷边、反向脉,存在多种不平衡结构和矿物组合,如斜长石环带、石英眼斑、针状磷灰石等,显示岩浆混合特征;包体的SiO2含量为48.40%～55.40%,寄主花岗岩SiO2含量为65.03%～72.85%,具有明显的SiO2含量间隔;与寄主花岗岩相比,包体的Fe、Mg、Ca、Ti含量较高;包体和寄主花岗岩的主要氧化物之间具有很好的线性关系,微量元素和稀土元素特征相似。包体和寄主花岗岩的这些地球化学特征显示出明显的岩浆混合趋势。岩相学和元素地球化学特征表明暗色包体是基性岩浆侵入到酸性岩浆淬冷的产物,牙马图岩体存在两种岩浆的混合作用。The Yamatu pluton in Nuoergong—Langshan area is located in the western part of the northern margin of the North China Craton. It consists mainly of monzogranite with many dioritic and gabbro enclaves. These enclaves have plastic shape and magmatic structure, quench boundary,back-up veins and unbalanced textures, such as acicular apatite, quartz ocellar texture and plagioclase zoning. Geochemically, SiO2 of the enclave samples vary from 48.40% to 55.40%, and the contents of Fe, Mg, Ca and Ti in the enclave samples are higher than those of their host granites. The enclaves and their host granites have similar characteristic of major and trace elements, and show good linear relationship in Harker diagrams of the enclaves and their host granites.These characteristics suggest that there should be obvious genetic relationship between the enclaves and their host granites. The TFeO—MgO diagram of the enclaves and their host granite shows a very clear trend of magma mixing. Petrography and geochemistry also evidence magma mixing. The enclaves from the Yamatu pluton are probbaly derived from quenching of mafic magma into felsic magma.

关 键 词：暗色包体 花岗岩 岩浆混合 地球化学 阿拉善 

分 类 号：P586[天文地球—岩石学]