内蒙古霍各乞铜多金属矿床含矿建造及矿床成因

Ore-bearing formation and genesis of the Huogeqi copper multimetal ore deposit in Inner Mongolia

霍各乞铜多金属矿床含矿岩层自下而上为:底板黑云石英片岩→碳质板岩(Pb、Zn主要赋矿层)→下条带石英岩(Cu次要含矿层)→透辉、透闪石岩(Pb、Zn及Fe主要赋矿层)→上条带石英岩(Cu主要赋矿层)→顶板二云石英片岩.斜长角闪岩出现在含矿层之下,顺层产出,与围岩侵入接触.矿石δ34S多集中在8‰～20‰,以火山硫为主;矿石的铅同位素组成属正常铅,在构造演化图上,落在上地幔与造山带铅演化线之间的克拉通化地壳边部.含矿建造ΣREE多在84 77×10-6～234 49×10-6,(La/Yb)N均>1.矿物包裹体组分类型为Na-Ca-F,Na-Ca-Cl型;均一温度150～464℃;成矿压力5MPa,pH6 5～7,Eh-0 5～0 18.经综合分析研究,该矿床属大陆裂谷环境的海底火山喷气沉积层控(变质)型,并总结出该区寻找此类矿床的找矿标志.

The ore-bearing layers of Huogeqi copper multi-metal ore deposit , from the bottom to the upper strata, are as follow:the footwall,biotite quartz schist→carbonaceous slate (the main ore-bearing bed of Pb and Zn)→lower ribbon quartzite (the minor ore-bearing bed of Cu)→diopside tremolite strata(the main ore-bearing bed of Pb and Zn and Fe)→upper strip quartzite (he main ore-bearing bed of Cu)→the top layer,mica quartz schist. Amphibolite, which occurs along the strata and intrusive contact to surrounding rock,is under the ore-bearing bed.δ^(34)S values of ore occur mainly between 8‰ to 20‰ and most of them are volcanogenic sulfur.The lead-isotope composition belongs to normal lead which enters the area of cratonization earth crust in the structure evolution diagram of lead evolution curve between upper mantle and orogenic belt. Most of ΣREE of ore-bearing formation are between 84.77×10^(-6) and 234.49×10^(-6), (La/Yb)_N are more than 1. The composition styles of inclusions are Na-Ca-F and Na-Ca-Cl. Their homogenization temperature is 150～464℃ and metallogenic pressures are 5MPa,pH 6.5～7, Eh -0.5～0.18. This ore deposit belongs to the sea bottom volcanic eruption-sedimentary-stratabound(metamorphic) type in the environment of continent rift.