广西凭祥地区金矿床地质地球化学特征研究

凭祥地区金矿床受断层构造与酸性火山岩的双重控制。围岩蚀变为黄铁矿化、绢云母化、硅化等。矿床的形成经历了两个成矿期 :热液成矿期与表生氧化期。热液成矿期金由热液迁移至围岩 ,被黄铁矿与毒砂吸附。表生氧化期黄铁矿与毒砂氧化形成氧化铁矿物 ,金被吸附到氧化铁矿物之上得到富集。对矿化岩石与围岩的微量元素与稀土元素分析结果表明 ,本区金矿以Au As Sb Hg组合为特征 ,As是金的找矿指示元素。根据金矿床的矿物组合与微量元素特征以及矿床地质条件推测 ,本区金矿床属低温热液矿床 ,形成时代为燕山期。

GEOLOGICAL AND GEOCHEMICAL CHARACTERISTICS OF GOLD DEPOSITS IN PINGXIANG AREA, GUANGXI

Gold deposits in the Pingxiang area are controlled by faults and hosted in acid volcanics. The alteration of acid volcanics is characterized by pyritization, sericitization, and silicification. The deposits were formed in two stages, namely hydrothermal mineralization stage and supergene enrichment mineralization stage. Gold migrated into host rocks and adsorbed onto pyrite and arsenopyrite during the hydrothermal mineralization stage. In the supergene mineralization stage, pyrite and arsenopyrite were oxidized to iron (hydr)oxide minerals and gold was enriched by adsorption onto the iron (hydro)oxide minerals. Analytical results for trace elements and rare earth elements of the mineralized rocks and host rocks show that the element association is Au As Sb Hg and As can be used as indicator element for gold prospecting in the area. Based on their mineral assemblage, element association and geological characteristics, the gold deposits are designated to low temperature hydrothermal ones and were formed during the Yanshanian period.