摘要
云南腾冲是中外著名的地热区，区内火山岩浆地热活动强烈，水热显示形式多样，有温泉、热泉、沸泉、水热蚀变岩石、泉华（硅华、盐华、钙华和硫华）等。其中硅华为较高温水热活动产物。新硅华以非晶质硅胶和蛋白石为主，含有少量的玉髓和石英；老硅华以玉髓和石英为主，含有硅胶和蛋白石。由硅华和钙华包裹体测温数据推断，现代热泉系统地热温度范围为１５７—２７０℃，压力为３０×１０５Ｐａ，现今热田的温压低于老硅华时期。已在热海热田发现金矿化，石英脉（花岗岩体中）和硅华具有显著高丰度的金。硅华中金含量最高达到０．３９ｇ／ｔ，平均值０．１６ｇ／ｔ。因此，本区具有良好的找金前景，硅华作为寻找热泉金矿的一种标志。
Being the most important geothermal area with active hydrothermal manifestations in China, Tengchong is world famous for its geothermal resources. Tectonically, Tengchong is located close to the junction zone of the Eurasian plate and the Indian plate. The residual magma gradually cooled down and became an ideal heat source for its overlying hot spring system. It is inferred from the thermometry of geyserite and adarce inclusions that underground temperatures for the hot spring system in Tengchong are 157—270℃. Surface hydrothermal alterations are well developed in the Tengchong active hot spring system. Tengchong has a great variety of special surface geothermal manifestations, such as warm springs, hot springs, boiling springs, sinters (geyserite, travertine, efflorescence etc .), hydrothermal explosive breccias, and hydrothermal altered rocks, which are surface manifestations of geothermal activity in the interior of the earth's crust. In this paper, mineral composition and chemical composition of geyserite in the Tengchong active hot spring system of Yunnan Province were studied by means of analytical electron microscopy (AEM) including transmission electron microscopy (TEM) and energy dispersive X ray spectra (EDS),scanning electron microscopy (SEM), X ray diffraction (XRD), infrared absorption spectra (IR), chemical analysis and optical examination. The results indicate that geyserite consists mainly of amorphous silica (silica gel), opal, chalcedony and quartz, and that silica gel is composed of micron sized (0.2—2μm) SiO 2 spherulites. Silica gel has played an important role in the enrichment of gold. Geyserite is only present in a few high temperature hot water areas, such as the Hot Sea and Ruidia. It is found that the hot spring system contains abundant gold mineralization. Quartz veins and geyserite have remarkably high gold abundance: 0.198 ppm for quartz veins and 0.155 ppm for geyserite (the highest value being 0.39 g/t). The enrichment of gold in geyserite provides an importan
出处
《岩石矿物学杂志》
CAS
CSCD
北大核心
1997年第2期170-178,T001,共10页
Acta Petrologica et Mineralogica
关键词
热泉系统
硅华
矿物学
地质意义
金矿床
active hot spring system
geyserite
hot spring gold deposit
Tengchong of Yunnan Province
