投稿时间：2024-08-19
修订日期：2025-04-17
网络发布日期：2025-07-01
中文摘要:拜仁达坝矿床是大兴安岭南段内典型的大型-超大型银多金属矿床。野外观察和矿相学研究表明该矿床热液成矿作用可划分为2个阶段：Ⅰ铜铅锌多金属硫化物-石英-萤石阶段；Ⅱ银多金属硫化物-石英-方解石阶段。为了查明该矿床银的赋存状态和富集机制，对矿床中主要矿石矿物组合进行了扫描电子显微镜-能谱分析和电子探针成分分析。结果显示，拜仁达坝矿床中含银矿物主要沉淀在Ⅱ阶段，银主要以多种独立银矿物形式存在，其次以显微-次显微银(辉锑铅银矿)呈他形粒状或细小不混溶包裹物出溶在方铅矿中，少量以类质同象银赋存于黝锡矿、方铅矿和黄铜矿等硫化物中。结合前人对该矿床的流体包裹体研究发现，当温度降至200℃左右时，Ag+开始与溶液内的Cu+、Pb+、Sb3+等金属离子结合直接沉淀或交代早期硫化物形成银黝铜矿(＜170℃)。随着成矿流体进一步演化和温度的降低，Ag+逐渐增加Cu+减少，依次形成辉锑铅银矿、深红银矿、脆银矿、辉银矿。当体系中Ag+逐渐消耗殆尽时，硫锑铅矿和不含银的方铅矿等矿物逐步沉淀。总之，成矿热液温度下降和pH值上升共同控制着拜仁达坝矿床的矿石矿物沉淀顺序、银的赋存状态及银矿物种类。
Abstract:The Bairendaba is a typical large and super-large Ag polymetallic deposit in southern Great Xing’an Range. Field observation and ore mineralogy studies reveal two-stage hydrothermal mineralization in the Bairendaba deposit: (Ⅰ) Cu-Pb-Zn polymetallic sulfides-quartz-fluorite stage and (Ⅱ) Ag polymetallic sulfides-quartz-calcite stage. To determine silver occurrence state and enrichment mechanism in the deposit, SEM-EDS and EPMA were performed on ore minerals. The results show that the silver minerals in the deposit are mainly precipitated in the stage-Ⅱ, and silver mainly occurs as various independent silver minerals, followed by the micro-submicroscopic silver (diaphorite) as anhedral granular or fine-grained immiscible solution occurs in galena, and a small amount of isomorphic silver occurs in sulfides such as stannite, galena and chalcopyrite. Combined with previous fluid inclusion studies of the deposit, it was found that, Ag+ began to combine with Cu+, Pb+, Sb3+ and other metal ions in the solution when the temperature dropped to about 200℃, and directly precipitated or replaced the early sulfides to form freibergite(＜170℃). With the ore-forming fluid evolved further and the decrease of temperature, the Ag+ gradually increased while Cu+ decreased, the diaphorite, pyrargyrite, stephanite and argentite were formed successively. When Ag+ was nearly exhausted in the system, minerals such as boulangerite and non-silver galena gradually precipitated. In general, the decrease of hydrothermal temperature and the increase of pH value control the precipitation sequence of ore minerals, silver occurrence state and the species of silver minerals in Bairendaba deposit.
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基金项目:本文得到内蒙古自治区自然科学基金青年基金(编号：2024QN04002和2024QN04006)和内蒙古科技厅中央引导地方科技发展资金项目(编号：2022ZY0084)联合资助
引用文本：
杨沙沙,曹明雨,苏慧敏,密文天,胡子付,李耿,李海东.2025.大兴安岭南段拜仁达坝Ag-Pb-Zn多金属矿床矿相学特征与银的赋存状态及沉淀机制[J].矿床地质,44(3):537~558YANG ShaSha,CAO MingYu,SU HuiMin,MI WenTian,HU ZiFu,LI Geng,LI HaiDong.2025.Mineral characteristics, silver occurrence state and enrichment mechanisms of Bairendaba Ag-Pb-Zn polymetallic deposit in southern Great Xing'an Range[J].Mineral Deposits44(3):537~558
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