【作者】 郑直； 吕达人； 周国平；

【Author】 Zheng Zhi,Lu Daren and Zhou Guoping (Institute of Mineral Deposits,Chinese Academy of Geological Sciences)

【机构】 矿床地质研究所；

【摘要】 腾冲地热区以热海热田为中心,其面积达100km~2,包括了数十个泉群。热区水热蚀变作用强烈,岩石发生强烈硅化、高岭土化和泥化作用,出现了以高岭石为主的一系列中低温蚀变矿物。根据蚀变矿物组合特征,蚀变区分为五个带:(1)硅化带;(2)明矾石化带; (3)高岭土化带;(4)泥化带;(5)规则混层带。从硅化带至泥化带,从热泉中心依次向外分布,规则混层带的分布和区域构造线一致。造成蚀变区大量高岭土化作用的主要因素是构造断裂活动和含铝岩石的多孔疏松结构。更多还原

【Abstract】 Tengchong,one of the largest geothermal area in China,covers an area of about 6000 km² and is noted for a great number of hot springs.Because of frequent geothermal activities,all the original rocks,mainly Late Tertiary arkose and arkosic conglomerate composed of granitic gravels,have been altered intensely.Of the alterations,kaolinization at surface has resulted in the formation of a kaolin deposit with latent economic value.The geothermal water shows slight acidity（ph=6—7.5）,varies from 70℃to 98℃in temperature and contains some H₂S.The hydrothermal alteration mineral assemblages can be represented by（1） siliceous minerals,dominantly quartz and opal;（2） sulfates,mainly alunite;（3） kaolin minerals,chiefly ordered-kaolinite with small amounts of halloysite and dickite;（4） montmorillonite and chlorite;（5） interstratified minerals consisting of regular interstratifications of I/M and Ch/M and also some of irregular ones;（6） phosphates such as goyazite and woodhouseite.Of all these,kaolinite is the most abundant clay mineral. From the center of the hot springs outwards several alteration zones can occur in the sequence of silicified—alunitized—kaolinized—argillized zone, and the distribution of regular interstratification zone is coincident with that of NS-trending faulted zone. The development of the altered minerals are controlled by three factors: （1） the property of original rocks.Generally speaking,granitoid has been altered into kaolinite,and basaltic rocks into smectite and chlorite;（2） the epithermal alteration which has led to the assemblage of kaolinite,alunite and quartz,and sulfur-bearing geothermal water which is responsible for the development of alunite and halloysite;（3） fault structure controlling the occurrence of hot springs and the distribution of regular interstratified minerals.更多还原