黑龙江金厂富钴斑岩型金矿床钴赋存状态和富集机理研究

钴是我国战略性关键金属，对外依存度达95%。目前大陆钴矿类型分为沉积层控型、岩浆型、风化型和热液型四大类，其中热液型富钴矿床亚类多样，多与基性-超基性岩有关，国内外尚无典型斑岩型富钴矿床的明确报道。黑龙江金厂大型金矿床（~76吨），矿体特征分为角砾岩型、裂控型和细脉浸染型，为斑岩型金矿床，初步研究揭示存在明显的钴富集，是研究斑岩型富钴矿床的理想对象。本申请拟以金厂为研究对象，利用EPMA、LA-MC-ICP-MS、SIMS等开展矿物原位结构、元素和同位素研究，查明钴的赋存状态和分布特征，揭示成矿过程中的同位素组成（如S-Fe和Cl-O-Sr-Nd），约束钴的物质来源。结合各阶段流体包裹体显微测温和原位成分研究，重点关注挥发份氯、硫与钴的协变关系，揭示钴在岩浆热液流体中的迁移行为，探讨钴沉淀的主控因素。该研究将有助于揭示钴在斑岩矿床中的地球化学行为和富集机理，并为斑岩型富钴矿床提供典型范例。

Cobalt is a strategic critical metal with its dependence on foreign sources of 95% in China. At present, the terrestrial cobalt deposits are mainly divided into four types: sediment-hosted stratiform type, magmatic type, lateritic type and hydrothermal type. Among them, hydrothermal cobalt-rich deposits have many sub-types, which are usually related to mafic-ultramafic rocks. Up to now, none of a typical Co-rich porphyry deposit is reported in the world. Heilongjiang Jinchang deposit is a large-scale gold deposit (~76 tons). The ore body features can be divided into breccia type, crack-controlled type and veinlet disseminated type. It is a porphyry type gold deposit. Preliminary research revealed obvious cobalt enrichment in this deposit. Thus, the Jinchang deposit provides us an ideal target to investigate the enrichment mechanism of Co in porphyry deposits. This project will fucus on this deposit, using the EPMA, LA-MC-ICP-MS, SIMS techniques to conduct in-situ mineral structure, element and isotope analyses, to determine the occurrence and distribution characteristics of cobalt. In addition, the isotopic compositions (such as S-Fe and Cl-O-Sr-Nd) will be used to constrain the source of cobalt. Combined with the microscopic temperature measurement and in-situ compositions of fluid inclusions at various stages, the covariant relationship between volatiles (chlorine and sulfur) and cobalt will be discussed to reveal the migration behavior of cobalt in magmatic hydrothermal fluids, and also to constrain the main controlling factors of its precipitation. This research will strengthen the geochemical behavior and enrichment mechanism of cobalt in porphyry deposits, and provide a typical example of cobalt-rich porphyry deposit.