| Paomaping lead-zinc deposit is located in the northeast of Jinding giant orefield in Lanping basin, northwestern Yunnan, SW China. The wall rock of Paomaping lead-zinc deposit is carbonate. Three exceeding industrial grade orebody from the top down, at level 2350m,2180m,2140m, respectively. Orebody along to wall rock almostly,with NE-SW strike, NW dip and high angle. It is a common phenomenon in mining area that sulfate, sufide and carbonate intergrow or company with each other. Therefore, various structure and texture in the orebody. Conclusions were obtained from geological mapping in Jinding orefield, geological logging in Paomaping gallery at level 2140m and evidence from the ore macro- and micro-texture.(1) Ore-forming is controlled with several thrust faults, underlaying the uncomformity surface of Yunlong formation and Sanhedong formation. Two large and thick gypsum rocks are present in the hanging wall and footwall of orebody.(2) Four mineralization and alteration zones from the center of orebody to the margin:dense massive lead-zinc orebody, vein type and disseminated ores, hematite-barytocelestite-calcitization and carbonatization.(3) Based on observation of a good deal of sections, four types relationship between sulfate-sulfide-carbonate have been concluded:encapsulate structure% intergrowth、growth zoning and Leisegang zoning. Establish the M-S-C-O multicomponent system logfo2-pH equilibrium phase diagram in 150 ℃ and 10wt%NaClequ. The advantage filed of each sulfate, sulfide and carbonate can be used to explanate the phenomenon of intergrowth and companion. In addition, oscillatory zoning of barytocelestite and Leisegang zoning consists of sulfate, sulfide, carbonate are all result from the intrinsic and internall inequilibrium in solid-solution.(4) With respect of barytocelestite, the replacement of Ba to Sr result in that incremental Sr atom in cellular linearly increase the cell parameter(Δa、Δb、ΔC、 V)and crystal plane spacing (d(hki)), linearly decrease the diffraction angle(Δ2θ). However, the fluctuant change locally may result from the replacement of othe atom with obvious atom radius gap between the replacer and Sr.(5) Five types of breccias in the deposit, whicn are separated by the cements. First type is fractured limestone with veins of red calcium and ferruginous clay-rich clastic cement. The second one is collapse breccia or solution breccia cemented by sulfide within orebody. The third one is solution breccias which present besides orebody, the cemented is composed of hydrothermal minerals, like calcite, celestine. The forth one is pseudo-breccia consist of an irregular framework of limestone cross-cut by labyrinth vugs are lined or filled with white calcite cement. The last one is composed of limestone fragment in a light grey green and light flesh red sandstone matrix.(6) Frequent tectonic activities, breccias composed of sphalerite limestone or sphalerite calcite fragment and hydrothermal mineral cements, colloidal sphalerite and pyrite, are all indicate possible existence of the ore-forming processes of multi-episoic fluid mixing. What’s more, ore-forming fluids may be characteristic of overpressure and episode.(7) Mineralization sequences of one ore-forming episode have been establish. Base on the sequences of mineralization, the evolution track of hydrothermal fluid feature of one episode could be depicted in M-S-C-O multicomponent system logfo2-pH equilibrium phase diagram. |
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