Evidence of mantle-rooted fluids and multi-level circulation ore-forming dynamics: A case study from the Xiadian gold deposit,Shandong province,China

Metallogensis of the Xiadian gold deposit in Shandong Province has been a question under dispute for a long time. There are many points such as metamorphic hydrothermal, magamatic hydrothermal and meteoric water. Detailed study shows that mantle-rooted fluids were involved in the ore-forming processes. Evidence for this argumentation comes from: (1) discor-dogenic fault; (2) intersecting and accompanying of basic veins and lodes; (3) geochemistry of stable isotopes; (4) geochemistry of fluid inclusions; and (5) multi-level circulation and exchanging of mantle-rooted fluids. Based on the characteristics of the circulation system of mantle-rooted fluids and its close relation to magmatic hydrothermal fluids and meteoric water, ore-bearing fluids are divided into three subsystems: (1) C-H-O-rich fluid circulation subsystem in mantle, (2) Si-rich fluid circulation subsystem in the middle and lower crust; and (3) S-rich fluid circulation subsystem in shallow and surface crust. Ore-forming functions of these subsystems are controlled respectively by their different geodynamic settings.