临沧锗矿含碳硅质灰岩的成因及其与锗成矿的关系  

Genesis of carboniferous siliceous limestone in the Lincang germanium deposit and its relation with germanium mineralization

作　　者：戚华文[1] 胡瑞忠[1] 苏文超[1] 漆亮[1] 

机构地区：[1]中国科学院地球化学研究所矿床地球化学开放研究实验室,贵州贵阳550002

出　　处：《地球化学》2002年第2期161-168,共8页Geochimica

基　　金：国家杰出青年基金(49925309);国家重点基础研究发展规划项目(G1999042310)

摘　　要：临沧锗矿是我国近年发现的具有独立开采价值且接近超大型规模的锗矿床,其富锗含煤段中存在薄层含碳硅质灰岩,深入研究含碳硅质灰岩的成因对于揭示锗矿床的成因具有重要的意义。通过对薄层含碳硅质灰岩岩石化学、微量元素、稀土元素和碳、氧同位素的系统研究,并与典型的陆相热水沉积物进行对比,得出以下初步认识:(1)含碳硅质灰岩属陆相热水沉积成因;(2)含碳硅质灰岩的微量元素和稀土元素可能主要来自基底的二云母花岗岩;(3)煤中锗主要由形成含碳硅质岩等热水沉积岩的热水带来。The Lincang germanium deposit is located in the coal bearing clastic Bangmai basin with granites as the basement rock in Lincang County, western Yunnan Province. There are three coal bearing cycles in the basin. Germanium that is present in the form of organic compounds mainly occurs in the lignite of the first coal cycle (N1b2) close to the basement granites. This cycle consists mainly of clastic rocks, coal seams, layered siliceous rocks and carboniferous siliceous limestones. At the top of Ge rich coal seams, the limestones tightly contact with germanium ore bodies. On the basis of major element, trace element, REE, δ13C and δ18O studies on the limestone in the Lincang germanium deposit, and comparison with some typical continental hydrothermal sediments, the genesis of carboniferous siliceous limestone and its relation with germanium mineralization is discussed. The carboniferous siliceous limestone is black with lamination conformation and inner clastic structure. Its CaO and CO2 contents are 79.47%～90.12%, the ratio of Al/(Al+Mn+Fe) vary from 0.004 to 0.04 (0.021 on an average), while the contents of CaO and CO2 of modern travertins in the Tengchong region are 93.47%～94.04% and Al/(Al+Mn+Fe) ratio 0.01～0.016. The limestone is mainly enriched in Sb, Ge, W, Ba, Cs, Sr and As. Its trace element characteristics are very similar to those of modern travertins in the Tengchong region. In the U Th diagram of different sediments (Rona, 1984), the Lincang limestones distribute in the area of Langban hydrothermal sediments. Compared to the basement, two mica granite, the limestone is obviously enriched in Ge, Sr, Ba and W, but the general trace element composition resembles that of the granites. Both the REE contents of the Lincang limestones and the Tengchong travertins are very low (less than 4.252 μg/g), their NASC normalized REE distribution patterns are basically accordant with each other, with obvious positive Eu anomaly. Meanwhile, the chondrite normalized REE distribution patterns of the Linca

关 键 词：含碳硅质灰岩 陆相热水沉积 锗矿床 岩石成因论 矿床成因论 云南 氧同位素 

分 类 号：P618.75[天文地球—矿床学] P588.244[天文地球—地质学]