海底喷流热水流体的来源一直是一个长期争论的问题，其成矿流体系统究竟是以海水为主还是以岩浆出溶流体为主？这两者分别对海底热水流体成矿系统产生多大的贡献？在成矿过程中两者如何混合又如何运移？传统技术方法难以给出确切的证据。基于以上考虑，本项目以四川呷村—赋存于晚三叠世海相钙碱性酸性火山岩系的典型块状硫化物(VMS)矿床为研究对象，从三维空间系统采集从下盘脉状-网脉状矿体热液石英脉、上盘块状矿体中的脉石石英，以及围绕矿体的热液蚀变矿物，开展系统的锂同位素研究，利用在同位素分馏过程中锂同位素表现出的独特个性，再加上海水中和岩浆水两个源区中的锂同位素比值差异较大的特性，并结合氧同位素分析，鉴别成矿流体系统中不同流体端员及其来源, 追踪和揭示端员流体混合过程, 详细再塑块状硫化物矿床的成矿过程。

As one of the world’s most important deposit type, VMS deposits represent a significant source of the world's Cu, Zn, Pb, Au, and Ag ores, and thus their genesis has caught much attention of the geoscience community. It is generally accepted that ore-forming fluids of such deposits were derived from the mixing of convective seawater with magmatic hydrothermal fluids, but specific proportions of the two types of fluids in ore-forming hydrothermal solution and their roles in the formation of VMS deposits still remain the subject of much debate. Additionally, detailed mixing process and subsequent evolution path of ore-forming fluids during formation of such deposits are still poorly understood. Traditional isotope tracer techniques had been intensively applied to determine the source and evolution process of ore-forming fluids in VMS deposits, but these methods are doomed to be ineffective. In the study, we plan to use lithium isotope tracer, a recently-emerged technique that can differ magmatic hydrothermal fluids from seawater easily due to their distinctly different lithium isotopic composition, to investigate the source and evolution process of ore-forming fluids in the Gacun deposits, Sichuan. During the study, samples from stringer-stockwork zones in the footwall, massive ore zones in the hanging wall, and alteration zones surrounding main orebodies will be systematically collected for lithium isotopic measurement. The aims of this study are to: (1) identify the source of ore-forming fluids in VMS deposits; (2) track mixing and subsequent evolution processes of different fluid end-members; and (3) reinforce genetic model for VMS deposits.