广西八渡金矿床含金硫化物矿物学与地球化学研究
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摘要
广西田林县八渡金矿床主要产于辉绿岩侵入体中,广泛发育乳白色石英网脉,蚀变辉绿岩体即为金矿体,具有硅化、粘土化、碳酸盐化和硫化物化等卡林型金矿热液蚀变特征。本文采用电子探针(EPMA)背散射电子图像(BSE)、波谱(WDS)和能谱(EDS)分析技术,对该矿床原生矿石中含金硫化物显微岩相学结构以及主量和微量元素含量和分布规律进行了系统研究,认为金主要是以不可见化学结合态金(Au+)的形式赋存于含砷黄铁矿和毒砂之中。含金硫化物与热液交代形成的金红石密切共生,并保留含钛铁辉石或钛铁矿等矿物的假象,金红石的形成是辉绿岩中含钛铁辉石或钛铁矿热液蚀变的产物,含金硫化物形成所需要的Fe来自辉绿岩中含钛辉石或钛铁矿等矿物的溶解,Fe的硫化物化过程是导致含金硫化物形成的重要机制。
Badu gold deposit mainly occurs within diabase intrusions in Tianlin County,Guangxi Province,China. It hosts within altered gabbro diabase,with intensive barren milky quartz veins and veinlets. The alteration related to mineralization caused silicification,argillization,carbonatization and sulfidation of gabbro diabase. In this paper,electron probe microanalysis( EPMA),backscattered electron image( BSE), wavelength dispersive spectrometer( WDS) and energy dispersive spectrometer( EDS) analyses were used to observe petrographic texture and determine element contents and distributions of S,Fe,Au,As and etc.,in gold-bearing sulfides of Badu gold deposit.Results show that gold mainly occurs as invisible chemical bonding( Au+) in the forms of arsenian pyrite and arsenopyrite. The gold-bearing sulfides occur with the hydrothermal rutile indicative the products of Ti-bearing clinopyroxene and ilmenite. Iron in sulfide minerals is probably derived fromdissolution of Ti-bearing clinopyroxene and ilmenite in the diabase,sulfidized by H_2S-rich fluids to precipitate gold-bearing arsenian pyrite and arsenopyrite.
Badu gold deposit mainly occurs within diabase intrusions in Tianlin County,Guangxi Province,China. It hosts within altered gabbro diabase,with intensive barren milky quartz veins and veinlets. The alteration related to mineralization caused silicification,argillization,carbonatization and sulfidation of gabbro diabase. In this paper,electron probe microanalysis( EPMA),backscattered electron image( BSE), wavelength dispersive spectrometer( WDS) and energy dispersive spectrometer( EDS) analyses were used to observe petrographic texture and determine element contents and distributions of S,Fe,Au,As and etc.,in gold-bearing sulfides of Badu gold deposit.Results show that gold mainly occurs as invisible chemical bonding( Au+) in the forms of arsenian pyrite and arsenopyrite. The gold-bearing sulfides occur with the hydrothermal rutile indicative the products of Ti-bearing clinopyroxene and ilmenite. Iron in sulfide minerals is probably derived fromdissolution of Ti-bearing clinopyroxene and ilmenite in the diabase,sulfidized by H_2S-rich fluids to precipitate gold-bearing arsenian pyrite and arsenopyrite.
引文
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[22]陈懋弘,毛景文,陈振宇,章伟.滇黔桂“金三角”卡林型金矿含砷黄铁矿和毒砂的矿物学研究[J].矿床地质,2009,28(5):539-557.
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[27]Hofstra A H,Cline J S.Characteristics and models for Carlin-type gold deposits[A].Reviews in Economic Geology[M].Hagemann S.G.and Brown P.E.(eds)GOLD IN 2000:163-220.
[28]Seward T M.Thio complexes of gold and the transport of gold in hydrothermal ore solutions[J].Geochimica et Cosmochimica Acta,1973,37(3):379-399.
[29]Seward T M.The hydrothermal geochemistry of gold[A].Foster RP,Eds.,Gold metallogeny and exploration.Blackie[M],1993,37-62.
[30]Heinrich C A,Eadington P J.Thermodynamic predictions of the hydrothermal chemistry of arsenic,cassiterite-arsenopyrite-base metal sulfide deposits[J]:Economic geology,1986,81:511-529.
[31]Pokrovski G S,Kara S,Roux J.Stability and solubility of arsenopyrite,Fe As S,in crustal fluids[J]:Geochimica et Cosmochimica Acta,2002,66(13):2361-2378.
[2]Simon G,Kesler S,Chryssoulis S.Geochemistry and textures of gold-bearing arsenian pyrite,Twin Creeks,Nevada:Implications for deposition of gold in Carlin-type deposit[J].Economic Geology,1999,94:405-422.
[3]Palenik C S,Utsunomiya S,Reich M.“Invisible”gold revealed:Direct imaging of gold nanoparticles in a Carlin-type gold deposit[J].American Mineralogist,2004,89:1359-1366.
[4]Reich M,Kesler S,Utsunomiya S,Palenik C S,Chryssoulis S L,Ewing R C.Solubility of gold in arsenic pyrite[J].Geochimica et Cosmochimica Acta,2005,69(11):2781-2796.
[5]Cline J S,Hofstra A H,Muntean J L,Tosdal R M,Hickey K A.Carlin-type gold deposit in Nevada:Critical geologic characteristics and viable model[J].Economic Geology.100th Anniversary Volume,2005,451-484.
[6]张复新,马建秦,陈衍景.秦岭卡林型金矿床金、砷地球化学探讨[J].地球化学,1999,28(5):453-463.
[7]肖龙.一种新的微细浸染型金矿——产于辉绿岩中的微细浸染型金矿特征及找矿标志[J].地质与勘探,1997,33(6):1-6.
[8]潘家永,张乾,邵树勋.桂西北发现一类新的微细浸染型金矿[J].黄金,1998,19(7):3-5.
[9]覃文明,何志美.桂西北与辉绿岩类岩石有关的金矿地质特征——以百色龙川金矿为例[J].黄金地质,2003,9(3):49-54.
[10]吴江,李思田,王灿,李甫安,谢家盈,李正海.桂西北微细粒浸染型金矿成矿作用分析[J].广西地质,1993,6(2):39-51.
[11]国家辉.桂西北超微粒浸染型金矿成矿地质条件及找矿模式[J].广西地质,1994a,7(2):37-50.
[12]国家辉.桂西北地区超微粒浸染型金矿标型特征[J].贵金属地质,1994b,3(4):289-292.
[13]国家辉.桂西北地区超微粒型金矿成矿条件及其成矿预测[J].贵金属地质,1994c,3(3):200,233-240.
[14]国家辉.桂西北地区超微粒浸染型金矿氧化矿形成条件及找矿[J].贵金属地质,1996,5(4):266-278.
[15]国家辉.桂西北地区岩浆活动与超微粒型金矿化的关系[J].贵金属地质,2000,9(3):133-143.
[16]谢世业,陈大经,李毅.桂西北热水沉积型金矿成矿系列、找矿标志及找矿前景[J].地质与勘探,2006,42(3):12-17.
[17]张敏,庞保成,吴荣华,李文龙.桂西北地区微细粒浸染型金矿地质特征和流体包裹体研究[J].现代矿业,2011,(12):50-52,85.
[18]覃少耀,颜小东.广西田林县八渡金矿地质矿化特征及成因研究[J].广东科技,2012,21(19):140-141,172.
[19]苏文超.扬子地块西南缘卡林型金矿床的成矿流体地球化学研究[D].贵阳:中国科学院地球化学研究所(博士论文),2002,1-116.
[20]Lubben J D,Cline J S,Barker S L L.Ore Fluid Properties and Sources from Quartz-Associated Gold at the Betze-Post Carlin-Type Gold Deposit,Nevada,United States[J].Economic Geology,2012,107(7):1351-1385.
[21]Su W C,Xia B,Zhang H T,Zhang X C,Hu R Z.Visible gold in arsenian pyrite at the Shuiyindong Carlin-type gold deposit,Guizhou,China:Implications for the environment and processes of ore formation[J].Ore Geology Reviews,2008,33(3-4):667-679.
[22]陈懋弘,毛景文,陈振宇,章伟.滇黔桂“金三角”卡林型金矿含砷黄铁矿和毒砂的矿物学研究[J].矿床地质,2009,28(5):539-557.
[23]Deditius A P,Reich M,Kesler S E,Utsunomiya S,Chryssoulis S L,Walshe J,Ewing R C.The coupled geochemistry of Au and As in pyrite from hydrothermal ore deposits.Geochimica et Cosmochimica Acta,2014,140:644-670.
[24]Su W C,Zhang H T,Hu R Z,Ge X,Xia B,Chen Y Y,Zhu C.Mineralogy and geochemistry of gold-bearing arsenian pyrite from the Shuiyindong Carlin-type gold deposit,Guizhou,China:Implications for gold depositional processes[J].Mineralium Deposita,2012,47(6):653-662.
[25]张弘弢.贵州水银洞卡林型金矿床含金硫化物地球化学与金的赋存状态研究[D].贵阳:中国科学院地球化学研究所(硕士论文),2007,1-88.
[26]苏文超.黔西南卡林型金矿热液化学及其成矿作用[R].广州:中国科学院广州地球化学研究所(博士后报告),2009,1-80.
[27]Hofstra A H,Cline J S.Characteristics and models for Carlin-type gold deposits[A].Reviews in Economic Geology[M].Hagemann S.G.and Brown P.E.(eds)GOLD IN 2000:163-220.
[28]Seward T M.Thio complexes of gold and the transport of gold in hydrothermal ore solutions[J].Geochimica et Cosmochimica Acta,1973,37(3):379-399.
[29]Seward T M.The hydrothermal geochemistry of gold[A].Foster RP,Eds.,Gold metallogeny and exploration.Blackie[M],1993,37-62.
[30]Heinrich C A,Eadington P J.Thermodynamic predictions of the hydrothermal chemistry of arsenic,cassiterite-arsenopyrite-base metal sulfide deposits[J]:Economic geology,1986,81:511-529.
[31]Pokrovski G S,Kara S,Roux J.Stability and solubility of arsenopyrite,Fe As S,in crustal fluids[J]:Geochimica et Cosmochimica Acta,2002,66(13):2361-2378.