【作者】 章永梅；

【导师】 顾雪祥；

【作者基本信息】 中国地质大学(北京) ， 矿物学、岩石学、矿床学， 2012， 博士

【摘要】 柳坝沟-哈达门沟金矿田是华北地台北缘中段乌拉山地区最大的金矿田，以广泛发育钾长石化碱交代蚀变为重要特征。长期以来，有关该矿田的研究大多集中在哈达门沟矿床，但在成岩成矿年代学、成矿物质来源和矿床成因等方面一直存在争议，有关碱交代蚀变、成矿流体特征和岩浆岩地球化学等方面的研究也较为薄弱，对柳坝沟金矿床的研究工作尚未开展，这在一定程度上制约了该区深部和外围的找矿进程。本文重点解剖了柳坝沟金矿床，并和哈达门沟金矿床进行了对比研究，深化了对矿田成矿地质背景、矿床地质特征、控矿因素和矿床成因的认识，指明了下一步的找矿方向。矿床产于晚太古代乌拉山群变质岩中，受断裂构造控制。矿体呈近EW向脉状产出，矿石类型有石英脉型、石英-钾长石脉型和钾硅化蚀变岩型。近矿围岩蚀变以钾长石化、硅化为主，向外侧逐渐过渡为绿帘石化、绿泥石化和碳酸盐化，局部见绢云母化。成矿过程分为钾长石-石英、石英-黄铁矿-绢云母-绿帘石/绿泥石、石英-金-多金属硫化物和碳酸盐4个阶段。元素地球化学、流体包裹体以及同位素研究表明，成矿流体以岩浆水为主，晚期有大气降水的加入；主矿化阶段的成矿流体总体属中高温度（200～350℃）、中低/中高盐度（5～45 %NaCl eq.）、中等密度（0.88～0.96 g/cm~3）的NaCl-H2O-CO2体系，沸腾可能是促使金等矿质大量沉淀富集的主要原因。成矿作用发生于中三叠世（218 Ma），与西沙德盖钼矿床（225 Ma）的成矿时代一致。成矿物质可能主要来源于以西沙德盖（245 Ma）、沙德盖（231 Ma）等岩体为代表的富硅、富碱质的印支期花岗质岩浆，部分来源于晚太古代乌拉山群变质岩。矿床属于与（偏）碱性岩浆（脉）有关的中高温岩浆热液矿床。原生晕地球化学研究结果表明，柳坝沟金矿床中Au、Mo、Ag、Pb、Ba为与成矿有关的元素组合，As、Sb、Hg、Ba为头晕元素组合，W、Mo、Pb、Bi为尾晕元素组合，Cu、Zn、Ag总体位于中部，基本属正向分带序列；局部头尾晕共存，As、Sb、Bi等反分带，显示出多阶段叠加成矿的特点。柳坝沟矿床主体上自西向东剥蚀程度逐渐变小，其剥蚀程度总体上小于哈达门沟矿床。综合地化参数和异常强度特征，认为柳坝沟矿床西段和中东段成矿远景好。上述认识得到了成因矿物学、流体包裹体、氢氧和硫同位素数据的佐证和钻探工程验证。综合研究认为，矿床受地层、构造、岩浆岩、围岩蚀变、地球物理、地球化学和矿物学等因素控制，在此基础上，确定了找矿标志，探讨了构造-岩浆-成矿作用过程，建立了矿床的成因模式和勘查模型。更多还原

【Abstract】 The Liubagou-Hadamengou gold field, located in middle north margin of NorthChina Platform, is the largest one in the Wulashan area characterizing by widespreadK-feldspathization. For a long time, most studies on this ore field were focused on theHadamengou ore deposit. However, some disputes still exist in diagenetic-metallogenic chronology, ore-forming materials and ore genesis, and the researcheson alkaline-metasomatic alteration, characteristics of ore-forming fluids andgeochemistry of magmatic rock is weak in this deposit. As for the nearby Liubagoudeposit, even no research has been carried out. Therefore, the peripheral and deepprospecting work of this area has been restricted to some extent. In this paper, basedon the detailed research on the Liubagou deposit and comparative studies on theLiubagou and Hadamengou deposits, the understandings about this ore field werefurther deepened on the aspects of metallogenic background, geological features ofore deposit, ore-controlling factors and ore genesis. Furthermore, the prospectingdirection was pointed out in this area.The ore field are hosted by Late Archaean metamorphic rocks of WulashanGroup, and controlled by faults. Ore bodies occur as nearly EW-trending vein, withore types of quartz vein, quartz-K-feldspar vein and potassic-silicified altered rock.Wall rock alterations are dominated by K-feldspathization and silicification adjacentto ore veins, and gradually transited to epidotization, chloritization, carbonatization,and weak sericitization away from ore bodies. Mineralization process is divided intofour stages, including K-feldspar-quartz stage, quartz-pyrite-sericite-epidote/chloritestage, quartz-gold-polymetallic sulphides stage and carbonate stage.Element geochemistry, fluid inclusion and isotope studies indicate that theore-forming fluids were dominated by magmatic water, though some meteoric waterwas added during later mineralization stage. The ore-forming fluids of mainmineralizing stage belonged to the NaCl-H₂O-CO₂system of medium-hightemperature （200³50℃）, medium-low / medium-high salinity （5⁴5 % NaCl eq.）and medium density （0.88⁰.96 g/cm3） generally. Boiling may have caused the precipitation of gold and other metals. Mineralization occurred in Middle Triassic（218 Ma）, this age is consistent with the metallogenic epoch of the Xishadegaimolybdenum deposit （225 Ma）. Metallogenic materials mainly derived from silicon-,alkali-rich Indosinian granite represented by Xishadegai （245 Ma） and Shadegai （231Ma） rock mass, and partly from Late Archaean metamorphic rocks of WulashanGroup. Hence, the Liubagou-Hadamengou ore field shows features of magmatichydrothermal （medium to high temperature） alkaline-related gold deposits.Primary halo results of the Liubagou deposit show that, the ore-formingassemblage is Au, Mo, Ag, Pb and Ba. The head halo is As, Sb, Hg and Ba, the rearhalo is W, Mo, Pb and Bi, as well as Cu, Zn and Ag generally occur in the middlesection of ore body. Thus, axial zoning sequence is basically positive. Meanwhile,coexistence of head and rear halos, as well as reverse zoning feature of As, Sb and Bishow the characteristics of multistage superimposed mineralization. In terms ofdenudation, it gradually declines from western to eastern part of num. 313 veins. Theore bodies of the Liubagou gold deposit are less denudated than the ones of theHadamengou gold deposit. Combined with features of geochemical parameters andintensity of anomaly, the western and eastern parts of num. 313 veins have a good oreprospecting potential. The understandings mentioned above are supported by resultsof studies on genetic mineralogy, fluid inclusion, as well as H-O and S isotopes andverified by drilling project.Comprehensive studies suggest that the ore deposit is controlled by the factorssuch as strata, structures, magmas, wall rock alteration, geophysics, geochemistry,mineralogy etc. Based on this, prospecting criteria is confirmed andtectonism-magmatism-mineralizaiton is discussed. Meanwhile, genetic andexploration models are established.更多还原