| The lead-zinc deposit concentration district of northeast Yunnan province, located in the southwestern margin of Yangtze Plate, is one of the most important origins of lead and zinc (silver). Taking Huize and Xiaohe lead-zinc deposits as a representative, geomechanics theory and measurement, tectonic-alteration mapping/profiling and tectonic geochemical analysis test are applied in this thesis to compare and research on tectonic systems, tectonic evolution, mineralized alteration zoning laws, regularities of structure-controlling. An important basis of metallogenic theory and prediction of blind deposits has been provided with the establishment of the ore-controlling structural model of the central-northern the Zn-Pb deposit concentration district in northeast Yunan. Results are as follows:1. Huize and Xiaohe lead-zinc deposits are both representative in tectonic background and regional location. Referring to the studies of tectonic trace and mechanical properties, tectonic systems and it’s evolution have been set up. During Jinning-Himalaya, the main compressive stress in northeast Yunnan province experienced the transition from near EW trending â†'NE-SW trending â†'NW-SE trending â†' near EW trending â†'near SN trending, forming the early SN tectonic belt, NW tectonic belt, NE tectonic belt, late SN tectonic belt and EW tectonic belt. After the formation of NE tectonic belt, some areas experienced NE-SW trending.2. By constructing tectonic-alteration sectional catalog, the mineralized alteration zoning laws and the control action of tectonics in Huize lead-zinc deposit were found. From ore body to wall rock, followed by Lead and zinc ore zone, Lead-zinc mineralization pyrite zone â†' Lead-zinc mineralization/pyritization coarse grain dolomite zone â†'Gray coarse grain dolomite zone, beige coarse grain dolomite zone, flesh red coarse grain dolomite zone, Net vein dolomitization limestone zone, Weak dolomitization limestone zone. In Xiaohe lead-zinc deposit, transformation is illustrated as Lead-zinc mineralization zoneâ†'pyrite mineralization zoneâ†' Silicification zoneâ†'dolomitization zone. The ore bodies and the mineralized alteration zones are mainly controlled by compressive and compression-tortion fault.3. Research of grading ore controlling regularity shows that in Huize lead-zinc deposit, Kuangshanchang-Jinniuchang tectonic belt connect regional deep faults and deposit. Kuangshanchang/Qilinchang/Yinchangpo thrust-folding limit the mineralization-alteration zone in the towed fold of the upper wall. As a favorable space of mineralization and hydrothermal alteration, interlayer faults strictly limits ore body’s and mineralization-alteration zone’s boundaries. In Xiaohe lead-zinc deposit, the regularity shows as following. NE main tectonic belts and Yaoshan tectonic belt control Lehong-Xiaohe orefield. Lehong-Shanwangmiao fault and Xiaohejie fault control Xiaohe lead-zinc deposit, restricting it in the rising blocks between the two faults. Secondary faults (NW/SN direction) control the distribution of ore body.4. According to the comparison of Huize lead-zinc deposit and Xiaohe lead-zinc deposit, central-northern section of the Zn-Pb deposit concentration district of northeast Yunnan province’s tectonic-ore-controlling model has been established:under compressive tectonic condition, compressive tectonic of regional and ore field level act as mine-leading tectonics. Secondary structure acts as ore-proportioning tectonics. The compressional faults and compressional-tortion faults (including interlayer faults) of the carbonate formation in the upper wall act as ore-hosting tectonics. However, the manifestations of tectonic ore-controlling might be different, essentially, lead-zinc deposits of the study area still belong to Huize type deposits. |
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