云南岩脚铅锌矿床地质特征及区域成矿作用对比
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摘要
岩脚铅锌矿床位于思茅中新生代拗陷盆地中,矿体主要赋存于下白垩统景星组地层中,零星小矿体赋存于和平乡组地层中。矿体主要呈脉状、透镜状产出,并受断裂构造控制,含矿岩性为黄白、灰白、黄绿色粉—细粒、中粒石英砂岩、岩屑石英砂岩。矿石中金属矿物组合为闪锌矿、方铅矿、黄铁矿、黄铜矿、毒砂,围岩蚀变主要有黄铁矿化、方解石化。区域岩石地球化学特征表明,盆地红层(T-E)中的Pb、Zn元素含量均较地壳克拉克值富集,盆地内红层可能为该区铅锌成矿提供了物质来源。其成矿过程为,在早白垩世,伴随碎屑岩的沉积作用,铅锌在岩石矿物颗粒之间初步沉淀、富集,伴随喜山期构造运动的发生、发展、深化,深部热卤水及构造热液在应力驱动下沿深大断裂向上运移,与所经岩层发生水岩反应,不断萃取所经岩层中的Pb、Zn等矿质,形成成矿热液,主要沿断裂、裂隙充填形成与其产状一致的脉状矿体,部分矿液叠加于早期形成的低品位矿体之上使之变富。矿床成因类型为沉积—热液改造型。
Yanjiao lead-zinc deposit is located in the Mesozoic-Cenozoic depression basin of Simao.The ore bodies are mainly hosted in the lower Cretaceous Jingxing Formation strata and sporadic small ore bodies are hosted in the Hepingxiang formation strata.The ore bodies are mainly veined and lenticular and controlled by faults.The ore-bearing lithology is yellowish-white,gray-white,yellowish-green powder-fine-grained,medium-grained quartz sandstone and lithic quartz sandstone.The metallic minerals in the ore are sphalerite,galena,pyrite,chalcopyrite and arsenopyrite.The main surrounding rock alteration is pyritization and calcification.The regional geochemical and petrochemical characteristics indicated that the Pb and Zn contents in the red beds(T-E)of the basinwere more abundant than those in the crustal Clark values,and the red beds in the basin may provide material sources for the Pb-Zn mineralization in this area.The metallogenic process was that in the early Cretaceous,accompanied by the sedimentation of clastic rocks,lead and zinc precipitated and enriched among the rock mineral grains,accompanied by the occurrence,development and deepening of the Himalayan tectonic movement,the deep hot brine and tectonic hydrothermal fluid migrated upward along the deep and large faults driven by the stress,and reacted with the rock beds.The Pb,Zn and other minerals in the strata were continuously extracted to form ore-forming hydrothermal fluid,which was mainly filled along faults and joints to form vein-like ore bodies with the same occurrence.Some ore fluids were superimposed on the low-grade ore bodies formed in the early stage to enrich them.The genetic type of deposit is sedimentary hydrothermal alteration deposit.
Yanjiao lead-zinc deposit is located in the Mesozoic-Cenozoic depression basin of Simao.The ore bodies are mainly hosted in the lower Cretaceous Jingxing Formation strata and sporadic small ore bodies are hosted in the Hepingxiang formation strata.The ore bodies are mainly veined and lenticular and controlled by faults.The ore-bearing lithology is yellowish-white,gray-white,yellowish-green powder-fine-grained,medium-grained quartz sandstone and lithic quartz sandstone.The metallic minerals in the ore are sphalerite,galena,pyrite,chalcopyrite and arsenopyrite.The main surrounding rock alteration is pyritization and calcification.The regional geochemical and petrochemical characteristics indicated that the Pb and Zn contents in the red beds(T-E)of the basinwere more abundant than those in the crustal Clark values,and the red beds in the basin may provide material sources for the Pb-Zn mineralization in this area.The metallogenic process was that in the early Cretaceous,accompanied by the sedimentation of clastic rocks,lead and zinc precipitated and enriched among the rock mineral grains,accompanied by the occurrence,development and deepening of the Himalayan tectonic movement,the deep hot brine and tectonic hydrothermal fluid migrated upward along the deep and large faults driven by the stress,and reacted with the rock beds.The Pb,Zn and other minerals in the strata were continuously extracted to form ore-forming hydrothermal fluid,which was mainly filled along faults and joints to form vein-like ore bodies with the same occurrence.Some ore fluids were superimposed on the low-grade ore bodies formed in the early stage to enrich them.The genetic type of deposit is sedimentary hydrothermal alteration deposit.
引文
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[2]李永才,刘吉金,魏江,等.云南岩脚铅锌矿床深部盲矿预测的构造叠加晕模型[J].矿产勘查,2016,7(3):479-487.
[3]管烨,王安建,李朋武,等.云南兰坪—思茅盆地中轴构造带的特征及其研究意义[J].中国地质,2006,33(4):832-841.
[4]罗君烈.滇西特提斯造山带的演化及基本特征[J].云南地质,1990,9(4):247-290.
[5]朱创业,夏文杰,伊海生,等.兰坪—思茅中生代盆地性质及构造演化[J].成都理工学院学报,1997,24(4):24-30.
[6]薛春纪,CHI Guoxiang,陈毓川,等.西南三江兰坪盆地大规模成矿的流体动力学过程—流体包裹体和盆地流体模拟证据[J].地学前缘,2007,14(5):147-157.
[7]李峰,黄敦义,浦为民.兰坪—思茅盆地红层铜矿成矿规律[J].大地构造与成矿学,1995,19(4):322-335.
[8]郝宏达,宋玉财,庄天明,等.金顶超大型铅锌矿床的成矿金属来源—来自铅同位素组成的制约[J].矿床地质,2017,36(2):379-390.
[9]王晓虎,宋玉财,候增谦,等.兰坪盆地北部白秧坪铅锌铜银多金属矿床地质特征[J].岩石矿物学杂志,2011,30(3):507-518.