江南造山带西南缘造山型金矿含炭质石英脉与金成矿关系研究

Study on Metallogenic Relations of Carboniferous Quartz Veins in Orogenic Gold Deposits in Southwest Margin of Jiangnan Orogenic Belt

江南造山带为金多金属复合成矿带,其矿床成因备受关注。许多矿床地质学者在这一问题上做出了大量的研究,对炭质在空间上与自然金及硫化物矿物有一定的联系,且有利于金的成矿已达成普遍共识,但就炭质的来源问题及它是如何影响金沉淀成矿机制的问题,尚有一定的争议。文章通过大量野外调查和室内显微镜下观察以及采用电感耦合等离子质谱仪(ICP-MS)对研究区金矿含炭质石英脉测试分析研究得出:炭质对金的矿化富集机制不仅存在化学作用的影响,也存在物理作用方面的影响。炭质可作为还原剂与Au(HS)2-发生氧化还原反应,使溶液中金的溶解度降低;亦可与硫化物矿物从热液中同时沉淀出来,实质是消耗热液中HS-的同时,破坏了Au(HS)2-的稳定性;同时,炭质所具备的较软弱、有滑感的物理性质,对金的富集有一定程度的帮助。

The Jiangnan Orogenic Belt is a gold-polymetallic complex metallogenic belt,and the genesis of its deposits has attracted much attention.Many ore deposit geologists have done a lot of research on this issue,and have reached a general consensus on the spatial relationship between carbon and natural gold and sulfide minerals,which is conducive to gold mineralization.However,there are still some disputes about the source of carbon and how it affects the mechanism of gold precipitation and mineralization.Based on a large number of field investigations,laboratory microscopic observations and ICP-MS analysis of the quartz veins of the carbonaceous quartz veins in the gold deposits in the study area,it is concluded that there are not only chemical but also physical effects on the mechanism of gold mineralization and enrichment.Carbon can be used as reductant to react with Au(HS)2-to reduce the solubility of gold in solution;it can also precipitate with sulfide minerals from hydrothermal solution at the same time,which is essentially to consume HS-in hydrothermal solution and destroy the stability of Au(HS)2-at the same time.At the same time,the weak and slippery physical properties of carbon are helpful to enrich gold to a certain extent.