Mineralization styles and structure-controlled mineralization rules of the Sanhe Pb-Zn Deposit in Inner Mongolia

Abstract

The Sanhe Pb-Zn deposit is studied in this paper through detailed field and underground geological investigations, structural geological surveys, drilling profile analysis combined with petrological and mineralogical analysis of ores and altered wall-rocks. We then discussed the ore-controlling structures and their distribution patterns, the styles of mineralization and alteration, the coupling relation between the mineralization and fault structures. Our results show that the mineralization in the Sanhe deposit show structure-controlled characteristics, and with dominant ore bodies trending NWW, dipping SSW. The extent of the ore-controlling faults can reach hundreds of meters to a few kilometers long, with relative stable occurrence. In the field, the ore-controlling faults occur as altered foliated zones but with tensional breccia veins and druse texture in them, showing a reactivated shear fault signature. NWW- and NNE- trending faults show post-ore deformation characteristics and usually with lamprophyre, syenite porphyry or calcite ±quartz ±fluorite ±clay mineral veins occuring in them. The NNW- and NNE- trending faults and related veins crosscut the mineralized carbonate-quartz veins and NWW-trending faults indicating a post-ore brittle deformation and hydrothermal activity. The post-ore faults and related hydrothermal veins usually occur as branching, bifurcation or irregular shapes and with druse texture in the center of the veins implying a extensional faults. Although the post-ore faults can slightly dislocate the ore bodies and contemporaneous hydrothermal veins, the displacement is negligible for exploration. The alteration around the non-mineralized calcite veins is dominated by clay alteration together with minor disseminated pyrite. Combined the structure-controlled mineralization and the alteration related Pb-Zn minerlization, it is concluded that the NWW-tending faults with silicification, pyritization, chloritization alteration halo, can be used as significant prospecting criteria in the deposit and the neighbouring area.

Keywords

• sanhe lead-zinc deposit
• mineralization styles
• structure-controlled mineralization rules
• wall-rock alteration
• ore prospecting criteria