【摘要】 内蒙古呼扎盖吐钼矿床是得尔布干成矿带上新发现的一座斑岩型钼矿床,钼矿体分布在燕山早期花岗闪长岩岩体内及其流纹岩接触带中,矿床以辉钼矿化和黄铁矿化为主,伴随有铅锌矿化和少量的黄铜矿化。成矿过程主要分为4个阶段:硅化阶段、石英-辉钼矿阶段、石英-多金属硫化物阶段和石英-方解石阶段。流体包裹体可分为富液相包裹体、富气相包裹体、含子矿物的多相包裹体和含CO₂的三相包裹体4种类型。以主成矿阶段为研究重点,对不同成矿阶段（Ⅱ→Ⅳ阶段）矿脉中石英/方解石中的包裹体进行了显微测温和激光拉曼探针分析。结果显示:石英-辉钼矿阶段,包裹体均一温度主要集中在280～400℃之间,盐度变化范围在2.57%～51.68%。该阶段富气相包裹体、含子矿物的多相包裹体和含CO₂的三相包裹体共存,L型包裹体液相成分主要为H₂O-NaCl,V型包裹体气相成分除H₂O为主外,部分还含有CO₂,含石盐子晶的三相包裹体,检测到不透明子矿物黄铜矿的峰值。发育铅锌矿化和黄铜矿化的石英-多金属硫化物阶段,包裹体均一温度集中在180～280℃之间,盐度变化范围为0.18%～9.73%。成矿晚期石英-方解石脉中仅发育L型的气-液两相流体包裹体,均一温度集中在140～240℃之间,盐度变化范围为0.35%～7.17%。结合最新研究成果,本文认为该矿床初始流体是中等盐度和密度的岩浆流体,在主成矿阶段由于压力释放发生流体沸腾作用,成矿流体系统的物理化学条件和氧化-还原环境发生骤变,导致辉钼矿和其他硫化物等成矿物质在脉状裂隙中发生卸载沉淀。更多还原

【Abstract】 The Huzhagaitu molybdenum deposit is a newly discovered porphyry deposit in the middle segment of the Derbugan metallogenic belt in Inner Mongolia. The molybdenum orebodies are mainly hosted within the Early Yanshan granodiorite, and its contact zone with rhyolite. The deposit is dominated by molybdenum mineralization and pyrite mineralization, accompanied by lead-zinc mineralization and a small amount of copper mineralization. The ore-forming process can be divided into four stages: silicification stage, quartz-molybdenum stage, quartz-polymetallic sulphide stage, and quartz-calcite stage. There are four types of fluid inclusions: liquid-rich phase inclusions, vapor-rich phase inclusions, multiphase inclusions including daughter minerals and CO₂-bearing three-phase inclusions. With the main mineralization stage as the focus of our research, this study carried out microscopic temperature measurement and laser Raman microprobe analysis for the inclusions in quartz or calcite in different mineralization stages（stage II to IV）. The results show that the homogenization temperatures of the inclusions in the quartz-molybdenum-pyrite stage are mainly concentrated between 280℃ and 400℃, and the salinities vary from 2.57% to 51.68%. In this stage, vapor-rich phase inclusions and multiphase inclusions including daughter minerals coexist with CO₂-bearing three-phase inclusions. The liquid phase composition of L-type inclusions is mainly H₂O-NaCl. The gas phase composition of V-type inclusions is mainly H₂O, and some of them also contain CO₂. Characteristic peak of laser Raman shift of daughter mineral chalcopyrite was detected in halite-bearing three phase inclusions. In the quartz-pyrite stage with lead-zinc mineralization and chalcopyrite mineralization, the homogenization temperatures of the inclusions are concentrated between 180℃ and 280℃, and the salinities vary from 0.18% to 9.73%. In late stage, only L-type inclusions occur in quartz-calcite veins, with the homogenization temperatures mainly ranging between 140℃ and 240℃, salinities varying from 0.35% to 7.17%. Combined with the latest research results, this paper suggests that the initial fluid of the deposit was magmatic fluid characterized by medium salinity and medium density. In the main stage of mineralization, the boiling of ore-forming fluid due to pressure release resulted in sudden change of the physical and chemical conditions of the ore-forming fluid system and the oxidation-reduction environment, causing the unloading and precipitation of molybdenite and other sulfide minerals in vein fractures.更多还原