| 云南金顶铅锌矿床地质特征及成因初探 |
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| 引用本文：.1985.Geological characteristics of the Jinding lead -zinc deposit in Yunnan with a special discussion on its genesis[J].Mineral Deposits,4(1):1~10 |
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| Geological characteristics of the Jinding lead -zinc deposit in Yunnan with a special discussion on its genesis |
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| Abstract:The Jinding lead-zinc deposit lies in the northern part of west Yunnan Mesozoic-Cenozoic depression. The strata are composed of two systems, i. e., autochthonous system and allochthonous one; the former refers to sediments of Upper Cretaceous time and Paleocene Yunlong Formation and the latter sediments of Upper Triassic, Jurassic and Lower Cretaceous times. Structurally, the whole mining area comprises an arch with the long axis trending NNE. From east to west, the deposit can be divided into three major ore-bearing members: Jayashan, Beichang and Fengzishan. Sandstone in Lower Cretaceous Jinxing Formation(K1,j)was overall mineralized, making up a thick bedded lead-zinc ore body. This deposit has an apparent vertical zoning with the upper part enriched in lead and the lower part in zinc; horizontally, it also shows an indistinct zoning with the east part enriched in zinc and the west part in lead. The ores might be grouped into sandstone type and limestone type, the former type possessing sedimentary oolitic, cemented and strawberry-like structures, while the latter type assuming metasomatic, corroded, concentric, gel, stockwork and banded structures; the ore minerals are mainly spha- lerite, galena, pyrite, the vein minerals are composed chiefly of quartz, calcite and secondarily of gypsum, celestite and some others. Trace elements in the ores are characterized by Sr>Ba, Sr: Ba=0.5-3, Zn: Cd=25-30, Mn=0.1-0.4％ and C=0.1-0.47％. Besides lead and zinc,the contents of such ore-forming elements as silver, cadmium and thallium in the country rocks are several times or even tens of times higher than the contents of these elements in the normal sedimentary rocks of the same types. Temperatures of inclusions contained in ore and vein minerals as determined by homogenization and decrepitation methods ate 160-334℃, and freezing determination shows that salinities of mineral inclusions are 7.4-1 4.6 wt％NaCl; microscopic studies have identified submineral facies of NaCl; spectrographic analysis of trace gases shows that inclusions generally have 0.01-0.78％CO2 and 0.08-1.21％H2O with celestite possessing the highest quantities of water. Lead isotopic modal ages are 22-83m. Y., approximately corresponding to ages of the stata; δS34 values vary in the range -1.71-30.43‰, character- ized by concentration of light sulfur. These data have led the authors to believe that the Jinding lead-zinc deposit is the product of early sedimentary-diagenesis and mineralization acted upon afterwards by late ore-bearing hydrothermal fluids, belonging hence to stratabonnd lead-zinc deposits of sedimentation plus late transformation type. |
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