刚果(金)加丹加鲁苏西铜钴矿床S、C、O、Sr同位素特征及矿床成因

Characteristics of S,C,O and Sr isotopes and genesis of the Luiswishi Cu-Co deposit in Katanga,Democratic Republic of Gongo

鲁苏西铜钴矿床位于刚果(金)加丹加铜钴矿带,是该区域典型层控铜钴矿床。该矿床的矿石类型依据氧化程度可分为硫化矿和氧化矿。野外地质观察和区域资料分析表明,硫化矿的成矿期可分为成岩早期和造山期,矿石矿物为黄铜矿、斑铜矿、硫铜钴矿和辉铜矿。氧化矿主要为铜钴硫化物在富水表生环境下淋滤而成。矿床的同位素数据分析表明:该矿床成岩期的硫化物为以生物还原作用为主,硫源来自元古宙海水,碳源以海相无机碳为主,放射性锶同位素与基底物质有关;造山期硫化物生成以热化学还原作用为主,成矿流体来自蒸发盐的溶解,硫源来自早期硫化物再活化和蒸发盐溶解,碳氧同位素表明成矿流体与围岩发生了强烈的缓冲反应。综合分析表明,蒸发相的海水为鲁苏西铜钴矿富集和成岩早期成矿提供了有利条件,造山期改造和表生期氧化对矿床品位的富集影响明显。

The Luiswishi deposit is one of the stratiform-hosted Cu-Co deposits in Katanga(DRC),the northern part of the Central African Copperbelt and in the peripheral of the Lufilian Orogenic Belt.The ore types in the Luswishi mine are classified as oxidized ore in oxidization zone and sulfide ore in depth based on the field survey and literature review.The mineralization stage consists of early diagentic,syn-orogenic and oxidation periods.Chalcopyrite,bornite,carrollite and chalcocite are the main Cu-Co sulfides;while malachite,chrysocolla and heterogenite are the most valuable oxidized ore.The isotope features of sulfides indicate that bacterial and thermochemical sulfate reductions mainly occurred during the diagenetic and syn-orogenic periods,respectively.From the analysis of isotopic characteristics it can be concluded that the main source of diagenetic mineralization might be leached from basement and the resulting minerals remobilized to provide source in the syn-orogenic period.Carbonate and organic matter in the Roan Group provided favorable conditions for the Cu^(2+) reduction in oxidized solution and precipitation in the carbonate strata.The supergene mineralization enriched the Luiswishi copper-cobalt deposit.