VMS型矿床在变质变形过程的元素迁移规律：以阿舍勒铜矿和可可塔勒铅锌矿为例

Volcanogenic Massive Sulfide (VMS) deposits provide huge amounts of Cu, Pb and Zn metals, and have therefore drawn high attentions from geoscientists and mining professionals. However, the element remobilization rules of VMS deposits during metamorphism and deformation are poorly understood. Our previous studies had illustrated the Ashele VMS Cu and Keketale VMS Pb-Zn deposits in the southern Altay experienced intense metal remobilization. In this proposal, based on the detailed identification of the ore minerals from the primary seafloor ore-forming stages to the subsequent reworked stages, we systematically analyze the contents and in-situ distributions of trace elements in the above-mentioned sulfides using LA-ICP-MS technique, and try to discover the available parameters that indicate element remobilization of the Ashele and Keketale VMS deposits. We aim to reveal the element remobilization rules of VMS deposits overprinted by metamorphism and deformation, and also to provide guidance to exploration of the metamorphosed VMS deposits in the orogen.

VMS型矿床受矿业界和学术界高度重视。借助现代洋底发现的黑烟囱，对VMS型矿床海底热液阶段成矿机理的认识已较为成熟。但大部分有工业价值的VMS型矿床都保存在现今造山带内，对其“登陆”后的保存和改造变化关注较少，尤其是其遭受变质变形改造时相关成矿元素的迁移规律研究匮乏。阿尔泰造山带是世界著名的VMS型矿带，阿舍勒铜矿和可可塔勒铅锌矿是该成矿带内具有VMS成矿特征的超大型矿床。本项目拟重点查明两个矿床变质变形条件及其对硫化物富集的控制规律；精细识别从原生海底热液成矿阶段到变质变形阶段的组构和矿物组合；利用LA-ICP-MS技术对上述硫化物及其过渡类型进行原位微区分析；提取用于指示VMS型矿床组分活化再迁移的指标性参数；对比分析富铜型和富铅锌型VMS矿石活化条件和组分迁移规律的异同点。预期成果可阐明VMS型矿床在不同变质变形条件下的元素迁移富集规律，为造山带内改造型VMS矿床的勘查提供科学支撑。

VMS型矿床受矿业界和学术界高度重视。借助现代洋底发现的黑烟囱，对VMS型矿床海底热液阶段成矿机理的认识已较为成熟。但大部分有工业价值的VMS型矿床都保存在现今造山带内，对其“登陆”后的保存和改造变化关注较少，尤其是其遭受变质变形改造时相关成矿元素的迁移规律研究匮乏。阿尔泰造山带是世界著名的VMS型矿带，阿舍勒铜矿和可可塔勒铅锌矿是该成矿带内具有VMS成矿特征的超大型矿床。本项目系统开展了矿物生成序列、成矿流体演化和成矿温度-压力条件等方面的研究，识别出阿舍勒VMS型铜矿和可可塔勒铅锌矿在区域变质过程中活化再富集的特征，该过程对于提高两个矿床的品位和储量具有重要意义，进而总结并提出了VMS型矿床的活化再富集的物理和化学识别标志。阐明了VMS型矿床在不同变质变形条件下的元素迁移富集规律，为造山带内改造型VMS矿床的勘查提供科学支撑。项目还识别出阿尔泰造山带内造山型锑金、铜、铅锌矿床的典型矿例，从而为完善造山型矿床理论提供重要资料。通过系统解剖本区印支期5个金、铜、铅锌矿床，发现其成矿年龄普遍晚于成岩年龄，成矿流体为富CO2变质流体，提出了该期成矿事件源于中亚造山带晚二叠-三叠纪造山作用，对于中亚造山带印支期成矿事件的认识具有开拓性意义。