内蒙古白云鄂博矿区富钾板岩的热水沉积成因特征  

GENETIC CHARACTERISTIC OF HYDROTHERMAL SEDIMENTATION OF K-RICH SLATE IN BAIYUN'EBO MINE,INNER MONGOLIA

作　　者：肖荣阁[1] 史淑玲[1] 安国英[1] 张汉成[1] 费红彩[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083

出　　处：《现代地质》2003年第3期281-286,T005,T006,共8页Geoscience

基　　金：国家自然科学基金项目(40073013);国土资源部国际合作与科技司自由探索项目(2000440)。

摘　　要：通过对白云鄂博富钾板岩的岩石学、矿物学及岩石化学的研究,提出富钾板岩是一种热水沉积钾长石岩的认识。富钾板岩是白云鄂博矿区的一种重要岩性,与上下岩层呈不规则层状或夹层产出,致密状微晶或隐晶质结构。其中钾长石含量在80%以上,X射线衍射分析表明其2θ(2-01)=21 00,2θ(060)=41 800,2θ(2-04)=50 560,求得三斜度Δ=0 91,有序度δ=0 89,属于典型的低钠、低温、有序最大的微斜长石,微斜长石成分占98%以上。岩石中富含微量元素B、F、Sr、Ba,平均质量分数分别为26×10-6、3386×10-6、119×10-6和1735×10-6,结合X射线衍射分析表明微斜长石中有冰长石成分。稀土元素以轻稀土富集、重稀土亏损、个别出现正铕异常为特征。根据热水流体中钾浓度与温度的相关性及热水沉积、交代和充填物中经常出现钾长石矿物,分析认为白云鄂博矿区出现的富钾板岩是热水沉积钾长石岩,其形成于火山期后的溶液活动阶段。Krich slate in Baiyun'ebo mine occurs in irregular form or interstratification with condensed microlite or cryptocrystalline structure. The content of Kfeldspar is more than 80%.By analysis of Xray diffraction,the data obtained are as follows:2θ(2-01)=2100, 2θ(060)=41800, 2θ(2-04)=50560,and triclinic degree is 091 and order degree is 089.So,Kfeldspar is typically epithermal microcline with lowerNa and the largest order, making up to 98%. There are high contents of trace elements such incompatible elements as B, F, Sr, and Ba,averaged out 26×10-6,3?386×10-6,119×10-6, and 1?735×10-6,respectively. Combined with the analysis of Xray diffraction, microcline contains somewhat of dulavia.The Krich slate is rich in light REE and poor in heavy REE, and even shows europium abnormal. Based on the correlation between K concentration and temperature, and analysis of the fact that Kfeldspar often appears in the replacement and filling material,it is suggested that Krich slate in Baiyun'ebo is hydrothermal sediment, which formed at the late period of volcanic solution activity.

关 键 词：富钾板岩 微斜长石 微量元素 稀土元素 白云鄂博矿区 

分 类 号：P581[天文地球—岩石学]