矾山杂岩体多元长石的成分、结构及其研究意义  

The Chemical Composition and Texture of the Multicomponents Feldspar in the Fanshan Complex,and Their Implications

作　　者：牟保磊[1] 邵济安[1] 张辉[2] 林斌[1] 阎国翰[1] 

机构地区：[1]北京大学地球与空间科学学院,北京100871 [2]中国科学院地球化学研究所,贵阳550002

出　　处：《矿物岩石地球化学通报》2013年第1期70-80,共11页Bulletin of Mineralogy, Petrology and Geochemistry

基　　金：国家自然科学基金资助项目(41172196)

摘　　要：华北早中生代矾山钾质碱性超镁铁岩-正长岩杂岩体由3个岩相带组成,本文在不同相带矿物学系统研究的基础上,重点对该区不同期次钾长石的组分和结构进行了详细的研究,其结果反映杂岩体总的具有富钾的特点,但各岩相带长石成分的差异则显示出不同期次岩浆成分上的不同。通过对长石的微量元素的进一步研究,本文首次确认了矾山地区钡冰长石和锶钡冰长石的存在。通过对不同阶段长石锶钡含量的比较研究,揭示了本区存在多次富钡流体的交代作用。该项研究对揭示本区岩石成因及其岩浆演化具有重要意义。岩浆晚期锶、钡元素的明显提高暗示:该区早中生代作为岩浆源区的岩石圈地幔有不断富集的趋势。The early mesozoic Fanshan potassic alkaline ultramafic-syenite complex in north China consists of three lithofacies. On the basis of the systematic mineralogy researches, this study focuses on compositions and textures of K-feldspars formed in different stages. The results show that the complex is generally rich in K and that the feld- spars in different lithofacies have different compositions, reflecting variation of the magmatic composition in differ- ent stages. Trace elements of the feldspars are further studied with hyalophane and strontium hyalophane identified for the first time in this area. The comparing study of the feldspars bearing Sr and Ba of different stages reveals multiphase mesomatism of K-rich fluids. This work is important to better understand lithogeny and magmatic evo- lutions of this area. The significant increasing of Sr and Ba contents in the later-period magma implies that the lithospheric mantle, which is the magma source, tended to enrich in the study area in the early Mesozoic.

关 键 词：化学组成 钾长石 钡冰长石 锶钡冰长石 矾山杂岩体 

分 类 号：P583[天文地球—岩石学]