熊耳山区中生代流体作用和成矿特征研究

The Shanggong gold deposit, the Kangshan gold-silver deposit and the Tieluping silver deposit, occur in NE-trending faults within the high-grade metamorphic basement and the MesoProterozoic volcanic cover of the Xiong'er Terrane. Their ore-forming process includes three stages marked, from early to late, by mineral associations of quartz-pyrite, multi-sulfides and carbonates, respectively. These three stage fluidization were occurred at high-, moderate- and low-temperature environments, respectively. From early to late, the capturing pressure of fluid inclusions became lower, suggesting the buried depth became shallower. This shows that the metallogeny was coeval with synorogenic crust-uplifting. As constrained by D-O-C isotope systematics, the ore fluid evolved from metamorphic, through mixing, to meteoric fluids. Combination of fluid boiling and mixing is usually the key for large-scale metallic accumulation. Boiling and mixing are usually caused by the compression-to-extension transition, which indicates that the large-scale mineralization in the Xiong'er terrane occurred in the collisional tectonic transition. C-Pb-Sr isotope systematics rules out the possibility that the metals were derived from various geological bodies in the Xiong'er terrane, including lower crust and mantle. Instead, they should be sourced from the sedimentary associations composed of the Luanchuan and Guandaokou Groups south of the Machaoying fault. Hence a tectonic model for collisional petrogenesis, metallogenesis and fluidization has been exclusively proved, i.e., a crustal slab containing the Luanchuan and Guandaokou Groups was subducted northwards beneath the Xiong'er Terrane along the Machaoying fault and provided enough ore-forming fluids through metamorphic devolatilization for the overlapping Xiong'er Terrane to develop the Au-Ag ore belt.

河南熊耳山地区金等矿床是碰撞造山体制形成的热液矿床，本项目运用激光拉曼探针、阴极发光显微热台联测系统、激光显微探针氩定年系统等先进技术，对其成矿流体综合研究，揭示成矿流体演化及其与构造演化的关系，据此窥探碰撞造山体制流体作用和成矿流体作用的规律性，试图弥补关于碰撞体制成矿流体研究之不足，故十分必要。