大兴安岭岔路口斑岩钼矿床流体成分及成矿意义

岔路口超大型斑岩型钼矿床位于大兴安岭北段，以网脉状和角砾岩型矿化为主.该矿床经历了4个成矿阶段:Ⅰ.石英-钾长石；Ⅱ.石英-辉钼矿；Ⅲ.石英-多金属硫化物；Ⅳ.石英-萤石-方解石.包裹体的岩相学及激光拉曼研究揭示，石英斑晶内的熔体-流体包裹体中熔体成分有更长石和钠长石，为岩浆出溶作用形成；子矿物多相包裹体(S型)中含有钾盐、石盐、赤铁矿和石膏等子矿物，显示出成矿流体为高氧逸度.第Ⅰ成矿阶段包裹体有气液两相(L+V型)、富CO₂三相(C型)和含石盐、钾盐、赤铁矿及硬石膏等子矿物的多相(S型)等类型，第Ⅱ成矿阶段除了有L+V型、C型以及含钾盐、石盐、黄铜矿和辉钼矿等子矿物多相(S型)外，还可以见到S型包裹体与气相包裹体(V型)共存；第Ⅲ成矿阶段以L+V型和含方解石的S型包裹体为主；第Ⅳ成矿阶段除见到L+V型包裹体外，还可以见到液相包裹体(L型).显微测温结果显示从早到晚，流体包裹体均一温度从530 ℃变为120 ℃、盐度从66.7% NaCl equiv变为1.2% NaCl equiv，呈现逐渐降低的趋势.群体包裹体成分显示各阶段均含有气相CO₂，液相成分中Na+，K+，Ca2+，SO₄2-，Cl-含量很高，而F-含量极少.成矿流体总体属于富含CO₂的高盐度、高氧逸度的NaCl-H₂O-CO₂体系，在流体演化过程中温度、氧逸度、盐度和CO₂含量逐渐降低.温度、盐度、CO₂含量逐渐降低及绢云母化影响了矿石沉淀. 

Compositions and Microthermometry of Fluid Inclusions of Chalukou Porphyry Mo Deposit from Great Xing'an Range: Implications for Ore Genesis

The Chalukou Mo deposit lies in the northern Great Xing'an Range, in which veinlet and breccia dominate mineralization. The whole hydrothermal ore-forming processes involve the following four stages: I. quartz-potash feldspar stage; II. quartz-molybdenite stage; III. quartz-polymetallic sulfide stage; IV. quartz-fluorite-calcite stage. The petrographic and laser Raman spectroscopy study show that the melt-fluid inclusions in quartz phenocryst contain component of oligoclase and albite, indicating they directly exsolved from primary magma. Halite, sylvite, hematite, and gypsum are recognized as daughter minerals in S-type inclusions of granite porphyry, suggesting high oxygen fugacity. The stageⅠquartz captures (L+V)-type, C-type, and S-type (contain halite, sylvite, hematite, and anhydrite daughter minerals) fluid inclusions. The stage Ⅱ quartz captures (L+V)-type, C-type, and S-type (contain halite, sylvite, chalcopyrite, and molybdenite daughter minerals) fluid inclusions, in addition, V-type and S-type fluid inclusions are coexistent. In the stage III, there are (L+V)-type and S-type with calcite as daughter minerals. Stage IV develops (L+V)-type and L-type fluid inclusions. Microthermometric data show the homogenization temperatures (530 ℃→120 ℃) and salinities (66.7% NaCl equiv→1.2% NaCl equiv) decrease gradually. The gas components have a certain amount of CO₂ in every stage, and the liquid components in fluid inclusions have Na+, K+, Ca2+, Cl-, and SO₄2-, and small amount of F-. The initial fluids are high oxygen fugacity and salinity NaCl-H₂O-CO₂ fluid system with abundant CO₂. The homogenization temperatures, salinities, lgf_O2, and CO₂ content tend to fall from the early to late stage. The decline of homogenization temperatures, salinities, and CO₂ content as well as sericitization greatly hinder the depositing of metallogenic elements.