云南大坪金矿床围岩蚀变和同位素地球化学特征

云南大坪金矿床主要赋存于闪长岩体中。由围岩至矿脉,形成自变质闪长岩带、绿泥石化带和碳酸盐化带的蚀变围岩分带,后二带与金矿化关系密切,宽度不一,渐渐过渡。在绿泥石化带中,带出的成分有SiO₂、Al₂O₃、Na₂O、FeO、Fe₂O₃、MnO、CaO、MgO、H₂O⁺、Li、W、Ta、Zr、V、Sc、Sn、Mo、Cr、Co、Ni、Cu、Pb、Au 和LREE,带入的成分有K₂O、P₂O₅、Ba、HREE(包括Y)、Ag、Zn。碳酸盐化带过程中, 带出的成分有SiO₂、Al₂O₃、Na₂O、K₂O、Ba、HREE(包括Y)、Mo、Sn、Pb、Zn、Ag,带入的成分有FeO、Fe₂O₃、M nO、CaO、MgO、H₂O+、P₂O₅、Li、Ta、Zr、V、Sc、Cr、Co、Ni、Au 和LREE,基本不变的成分有W、Cu。矿脉中铁白云石的δ¹⁴C值为-4.81‰,接近于深成碳;(⁸⁷Sr/⁸⁶Sr)为0.709019±72,∈Nd (0)为-17.34, fSm/Nd为-0.34,起源于地壳;蚀变强烈的围岩的δ¹⁸O值高,表明蚀变热液为非大气降水;金属硫化物(黄铁矿、方铅矿、黄铜矿和闪锌矿)的δ³⁴S为-4.0‰～11.1‰,成矿热液的Σ³⁴S从早阶段到晚阶段增高。

THE GEOCHEMISTRY CHARACTERISTICS OF WALLROCK ALTERATION AND ISOTOPES OF THE DAHE GEOCHEMISTRY CHARACTERISTICS OF WALLROCK ALTERATION AND ISOTOPES OF THE DAPING GOLD DEPOSIT

The Daping gold deposit,Yunnan,is dominantly hosted by diorite.From the distal wallrock to the vein,alteration zonings of autometamorphic diorite,choritization and carbonatization form.The later two zones are closely related to g old mineralization,gradually changing with different  width.SiO2,Al₂O₃,Na₂O,FeO,Fe₂O₃,MnO,CaO,MgO,H₂O+,Li,W,Ta,Zr,V,Sc,Sn,Mo,Cr,Co,Ni,Cu,Pb,Au and LREE decrease in chloritization zone; in contrast,K₂O,P₂O₅,Ba,HREE (including Y),Ag and Zn increase. In the carbonat izat ion prosess,SiO₂,Al₂O₃,Na₂O,K₂O,Ba,HREE(including Y),Mo,Sn,Pb,Zn and Ag are taken out;FeO,Fe₂O₃,MnO,CaO,MgO,H₂O⁺,P₂O₅,Li,Ta,Zr,V,Sc,Cr,Co,Ni,Au and LREE are taken in;W and Cu are basically unchanged.δ¹⁴C,(⁸⁷Sr/⁸⁶Sr),∈Nd (0) and fSm/Nd of the ferro dolmite of the ore vein are separately -4.81‰ which is near to the value of deep carbon,0.709019±72,-17.34 and -0.34,indicating a derivation of crust.Thestronger the rock is altered,the bigger the δ¹⁸O of the rock is,by that means the altering hy drothermal fluid is not meteoric,The value range of δ³²S of sulfides (including pyrite,galena,chalcopyrite and blende) is between -4.0 to -11.1‰ the Σ³⁴S of the hydrothermal fluid increases from early mineralization stage to late stage.