高硫-低硫化浅成低温热液矿床的短波红外矿物分布特征及找矿模型——以西藏铁格隆南(荣那矿段)、斯弄多矿床为例

Alteration Zoning and Prospecting Model of Epithermal Deposit Revealed by Shortwave Infrared Technique: A Case Study of Tiegelongnan and Sinongduo Deposits

本文以铁格隆南(荣那矿段)高硫化浅成低温热液矿床和斯弄多低硫化浅成低温热液矿床为研究对象,运用短波红外技术快速厘定了上述两个矿床的蚀变矿物类型及组合特征,构建了基于短波红外勘查技术的找矿模型。研究发现:铁格隆南矿床(荣那矿段)的蚀变矿物垂向分带组合为:高岭石→高岭石+(地开石+明矾石)→高岭石+明矾石+(地开石)→高岭石+地开石+明矾石。由于高硫化浅成低温热液交代黄铁绢英岩化带的斑岩型矿体,致使上部矿石中还有少量交代残余的绢云母;斯弄多低硫化浅成低温热液矿床的蚀变矿物垂向分布为:白(绢)云母+(钠云母)→白(绢)云母+钠云母+(伊利石)→白(绢)云母+钠云母+蒙脱石+伊利石→白(绢)云母+钠白云母+蒙脱石+伊利石,其中顶部白(绢)云母是后期黑云母花岗斑岩蚀变所产生,本身与成矿无关;矿体主要赋存在伊利石+蒙脱石带,随着蒙脱石被伊利石化,矿体也逐渐尖灭。

With the Tiegelongnan(Rongna ore block)high sulfidation epithermal deposit and the Sinongduo lowsulfidation epithermal deposit as the research objects and on the basis of the shortwave infrared technology,theauthors determined alteration and mineral assemblages of the two deposits,and built a shortwave infraredprospecting model.It is found that the alteration minerals in the Tiegelongnan deposit(Rongna)exhibitsvertical zoning of kaolinite→kaolinite+(dickite+alunite)→kaolinite+alunite+(dickite)→kaolinite+alunite+dickite.Owing to the metasomatism of hydrothermal on beresitization zone of porphyry,there is a small amount ofremanent sericite on the top.Minerals in the Sinongduo deposit show the vertical zoning of muscovite+(paragonite)→muscovite+paragonite+(illite)→muscovite+paragonite+illite→muscovite+paragonite+montmorillonite+illite.The muscovite at the top was produced by the alteration of the late biotite granite porphyry.It had nothing to dowith mineralization.The orebody is mainly hosted in the illite+montmorillonite belt,and the orebody is graduallypinched out as the montmorillonite with illitization.