摘要
Abstract
The Shaxi deposit is one of the important porphyry Cu-Au deposits in the Middle-Lower Yangtze River Metallogenic Belt,where gold grades vary markedly within the ore bodies and ores of different grades exhibit distinct mineralogical and geochemical characteristics.This study focuses on high-grade gold ores from the Fengtaishan ore block of the Shaxi deposit.Based on optical mineralogical observations,TIMA automated mineral analysis,electron probe microanalysis(EPMA),and in situ LA-ICP-MS analyses,the elemental composition,mineral assemblages,and gold occurrence characteristics of the high-grade ores were systematically investigated and compared with those of low-grade gold ores from the same ore block.The results show that the high-grade gold ores contain relatively high concentrations of Cu,Au,and Ag,and have a significantly higher overall abundance of sulfides than the low-grade ores.The metallic mineral assemblage is dominated by chalcopyrite and bornite.Gold occurs mainly as visible gold minerals,including native gold and electrum,and is predominantly present as liberated grains,whereas invisible gold accounts for only a very small proportion.Comparative analysis shows that high-and low-grade gold ores display systematic differences in sulfide abundance,the proportion of visible gold,and the grain-size distribution of gold minerals.These differences reflect distinct mineralogical and geochemical responses to gold enrichment within the Shaxi deposit and provide basic information for distinguishing ore-grade variations and identifying high-grade gold mineralization.关键词
沙溪矿床/高品位金矿石/矿物组成/金的赋存状态/地球化学特征Key words
Shaxi deposit/high-grade gold ore/mineral assemblage/gold occurrence/geochemical characteristics分类
矿业与冶金
