湖南辰溪仙人湾埃洛石型高岭土矿床特征及成因分析

ANALYSIS ON THE CHARACTERISTICS AND ORIGIN OF HALLOYSITE TYPE KAOLIN DEPOSIT AT XIANRENWAN,CHENXI COUNTY,HUNAN

在野外地质矿化特征调查的基础上,通过化学成分分析、光学显微镜、红外吸收光谱、X射线衍射、扫描电镜等手段,对新发现的湖南辰溪仙人湾埃洛石型高岭土矿床特征及成因进行研究发现:此高岭土矿体呈似层状与囊状形态,就位于二叠系/石炭系角度不整合面及二叠统/下二叠统假整合面上,分布在岩溶洞穴体系中。矿石中主要矿物为1nm管状埃洛石,部分为0.7 nm管状埃洛石,原生带矿石中埃洛石的含量达95%以上。该高岭土矿床为次生淋滤胶体溶液沉积-重结晶成因高岭土矿床矿床,系温暖湿润、岩溶发育的环境中,受强淋滤作用,由来自上覆地层砂页岩、煤层、泥灰岩及泥质灰岩中的硅铝物质经过相对富集,形成硅铝溶胶,迁移,在岩溶洞穴中沉淀并再次富集成为凝胶体,脱水老化形成埃洛石。

On the basis of geological investigation on mineralization, the characteristics and origin of halloysitic kaolin deposit have been analyzed by means of chemical composition analysis, optical microscope, infrared absorption spectroscopy, X ray diffraction and scanning electron microscope. The halloysitic ores occurred as sack-like and bed-like orebodies in karst cavities clung to the Permian/Carboniferous unconformity interfaces and the Upper/Lower Permian interface. 1nm halloysite is the dominant mineral for all detected samples, only a small portion has dehydrated and transformed to 0. 7 nm halloysite in parts of these samples. Halloysite content of ores from primary zone reached 95% above. The halloysitic ores at the orefield are secondary colloid precipitation and recrystallization origin. In warm and wet karst environment, under intensively leaching process, matter contain silicon and aluminum from sand-shale rock, coal bed, marlite and argillaceous limestone of overlying strata become relatively enriched, then form sol contain silicon and aluminum. Then the sob is magrated to karst caves and enriched again to form gel. Fi- nally,the gel formed halloysite due to of dehydration and aging.