临沧超大型锗矿床的沉积环境、成岩过程和热液作用与锗的富集

Sedimentation, diagenesis, hydrothermal process and mineralization of germanium in the Lincang superlarge germanium deposit in Yunnan Province, China

临沧超大型锗矿床的形成与其沉积、成岩和热液作用有密切联系。详细研究了该矿床煤岩产出特征、煤岩组成、无机矿物、微量元素、腐殖体反射率，认为该矿床中的锗主要源于盆地西线的白云母花岗岩的风化作用。在沉积作用阶段，锗被湖水中的低等生物和腐植酸富集，为形成矿化煤打下基础。临沧褐煤经历了泥炭化阶段、早期成岩阶段和热液改造阶段。泥炭化阶段，沉积物中锗被凝胶体吸附和配合。早期成岩阶段，与腐殖酸结合的锗，在碱性还原条件下，大部分发生转移进入到腐殖体的结构中；小部分锗仍与没有缩合成腐殖体的腐植酸形成螫合物或腐殖酸盐。热液改造阶段，循环加热的天水或来自基底的流体经过处于构造软弱带中的煤层，SO2-4被还原，生成热液黄铁矿，同时沉淀出方解石，对于锗起到叠加富集的作用。

The mineralization was related closely to sedimentation, diagenesis and thermal processes. Investigations were carried out on coal occurrence, maceral composition, inorganic minerals, trace elements, and huminite reflectance. It was concluded that the source of Lincang superiarge deposit was mainly the muscovite granite in the west edge of Bangmai Basin. During sedimentation, Ge was leached out and entered the basin where Ge was adsorbed by lower organism and humic substances in water. Lincang lignite underwent three thermal processes:peatification, early diagenesis and hydrothermal transformation. During peatification, Ge was adsorbed or complexed by humic colloids. During early diagenesis, the Ge associated with humic acids was hard to mobilize or transport. Most of Ge entered the structure of huminite while a small amount of Ge was associated with residual humic acids as complex or humate. During hydrothermal transformation, the heated natural water or deep fluid from basement encountered the coal layer within tectonic weak zone. SO2-4 was reduced by coal organic matter, and pyrite and calcite formed. Hydrothermal process may be significant to mineralization.