内蒙古哈达门沟金矿床成因及控矿规律探讨

哈达门沟金矿床地处华北克拉通北缘阴山隆起带南缘乌拉山复背斜南翼，金矿体主要产于新太古界乌拉山群变质岩中，主要矿石类型包括含金石英脉、含金石英一钾长石脉、含金钾化蚀变岩等。成矿流体主要为中低温（160—300℃）、中低盐度（5％-15％），气相成分以H2O和CO2为主，液相组分阴离子以Cl^-和SO2^-为主，阳离子以Na^＋、K^＋和Ca^2＋为主。矿石6Ms变化于-21．7‰～5．4‰，极差为27．1‰，说明成矿物质来源的复杂性，平均值为-10．6‰，表现出亏损重硫的特点，硫继承了太古代地层中硫的同位素特点，并混有深部含矿流体的硫。矿石铅同位素组成、单阶段模式年龄、Th／U比值、肛值变化范围较大，表现出多源特点，在铅构造模式图上，投点比较分散，表明哈达门沟矿石铅来源的复杂性。氢一氧同位素表明，成矿流体来源于岩浆水和部分变质热液，后期有天水的混入。矿石辉钼矿Re-Os同位素加权平均年龄为（386．4±2．7）Ma，等时线年龄为（386．6±6．1）Ma，金矿床主要成矿时代为早泥盆世，后期有多期热液活动叠加。矿床形成于弧一陆碰撞后的伸展构造背景。金矿脉严格受构造控制，具有等距分布，矿体在平面上和垂向上分段富集、分支复合、舒缓波状以及侧伏等现象，矿化表现为上金下钼、成矿多期多阶段等规律特点。

Study on genesis and ore-controlling rules of Hadamengou gold deposit in Inner Mongolia

Hadamengou gold deposit in Inner Mongolia is one of the important deposits, located in the southern margin of Wulashan antielinorium of Yinshan uplift, on the north margin of North China Craton. The gold orebodies mainly lie in the metamorphic rock of Wulashan Group, Archaeozoic erathem, the main ore types of which include gold-beating quartz vein type, gold-bearing quartz-potassic feldspar vein type, and gold-beating altered rock type. The ore-forming fluid is characterized by intermediate-low temperature （ 160 - 300 ℃ ）, and mid-low salinity （ 5 % - 15 % ）. The gas component of fluid inclusions is dominated by H20 and CO2. The main anions in the liquid composi- tion are CI- and SO42- and the cations are Na＋ ,K＋ and Ca2＋. The sulfur isotope composition of the ore 34S vary from -21.7 %o to 5.4 %0 with the change range of 27.1%0 and the average value is -10.6 %o, indicating the sources of ore-forming material are complex and sulfur isotope composition inherited the characteristics of those in archean strata, mixed with sulfur in deep-sourced ore-beating fluids. Lead isotopic compositions of the ore, single-stage model age, Th/U ratios, and/z value all vary in a large range,featuring multiple sources characteristics. In plumbotectonic model diagram by Zartman and Doe, the lead isotopic compositions of ore mineral plotted scattered which demonstrates that the ore lead came from mixed lead. Hydrogen and oxygen isotopes show that the ore-forming fluid was derived from magmatic and small metamorphic water and later mixed with meteoric water. Molybdenite Re-Os weighted mean age is （386.4 ±2.7 ） Ma and isochron age of the ore stone is （ 386.6 ± 6.1 ） Ma, which shows the main metallogenic epoch is early devonian and later multi-phase hydrothermal activity probably superimposed on the early stages. The deposit formed in intracontinental extensional tectonic setting after arc-continental collision. Gold-bearing veins are bound strictly by fault structures and distributed in parallel and equidistant arrangement, section enriched, bifurcation-com- plex, lateral trending, and smooth-out waveforms, etc. The mineralization appeared to have the characteristics of being multi-period and multi-stage with gold on the upper portion and molybdenum at the lower portion.