摘要
川滇黔铅锌矿集区位于扬子地块西南缘,发育有400多个矿床(点),铅锌矿石储量超2亿t,Pb平均品位(质量分数)达5%,Zn平均品位达10%。矿体主要呈似层状、脉状赋存于震旦系—二叠系碳酸盐岩地层中,为碳酸盐岩容矿后生铅锌矿床。文中通过综合分析川滇黔矿集区21个典型矿床的S-Pb多元同位素数据,示踪成矿元素主要来源,并为进一步找矿提供指导。研究区大部分铅锌矿床硫化物的δ34S值介于9.0‰~28.6‰之间,与震旦系—二叠系地层中海水硫酸盐δ34S值(+8.0‰到+38.7‰)相似,暗示研究区铅锌矿床硫化物中的S主要来源于赋矿地层中海水硫酸盐,TSR作用是还原硫的主要生成机制。部分矿床中,含硫有机质热解可能是还原硫的另外一种生成机制。该区硫化物Pb同位素组成显示4种不同的成矿物质来源模式:(1)唐家等矿床Pb主要来源于基底岩石;(2)金沙厂、乐马厂、乐红等矿床Pb主要来源于基底富放射性成因Pb的岩层及盖层沉积岩中富有机质地层;(3)会泽、天宝山、茂租、银厂沟、大梁子、云炉河、毛坪、富乐、杉树林、天桥等矿床Pb主要来源于基底岩石和沉积盖层中多源流体的混合,峨眉山玄武岩可能提供少量成矿物质;(4)青山、赤普、银厂坡、筲箕湾、板板桥等矿床Pb主要来源于沉积盖层,基底岩石提供了部分成矿物质。典型矿床的S-Pb同位素组成特征表明成矿物质具有混合来源的特征。
The Sichuan-Yunan-Guizhou(Chuan-Dian-Qian)Pb-Zn metallogenic province,located along the western margin of the Yangtze block,comprises more than 400 ore deposits or prospects.The average Pb and Zn grades of its 200 Mt ore reserve are 5 and 10 wt%,respectively.The Pb-Zn ore bodies mainly distributed as stratoid or vein-type within the Sinian to Permian carbonate rocks,suggesting a typical epigenetic Pb-Zn mineralization.In this study,isotope data of S and Pb sulfides from 21 deposits were compiled to reveal the source of ore-forming materials,and provide guidance for further prospecting.Theδ34 S values of most sulfide minerals range from +9.0‰ to +28.6‰,similar to the Sinian-to-Permian seawater sulfate(+8.0‰ to+38.7‰).It suggests that S in sulfides mainly came from thermochemical sulfate reduction(TSR)of the host-strata seawater sulfate.In addition,thermal decomposition of sulfur-bearing organic matter could provide part of reduced sulfur in mineralization in some Pb-Zn deposits.The Pb isotopic compositions of sulfides in the research area indicate four possible Pb sources:(1)Pb of the Tangjia deposit originated mainly from the basement rocks;(2)Pb in the Jinshachang,Lemachang and Lehong deposits mainly came from basement rocks containing radiogenic Pb isotopes and cap rock organic-rich sediments;(3)Pb of the Huize,Tianbaoshan,Maozu,Yinchanggou,Daliangzi,Yunluhe,Maoping,Fule,Shanshulin and Tianqiao deposits originated primarily from basement rocks and ore-forming fluid of multiple metal-bearing brine mixing in the cap stratum,and partly from Permian Emeishan basalt;(4)Pb of the Qingshan,Chipu,Yinchangpo,Shaojiwan and Banbanqiao deposits mainly came from sedimentary rocks,and partly from basement rocks.Themultiple S-Pb isotope composition in typical Pb-Zn deposits is indicative of mixed origin for ore-forming materials in the metallogenic province.
引文
[1]柳贺昌,林文达.滇东北铅锌银矿床规律研究[M].昆明:云南大学出版社,1999.
[2]ZHOU J X,HUANG Z L,ZHOU M F,et al.Constraints of C-O-S-Pb isotope compositions and Rb-Sr isotopic age on the origin of the Tianqiao carbonate-hosted Pb-Zn deposit,SWChina[J].Ore Geology Reviews,2013,53(8):77-92.
[3]ZHANG C Q,WU Y,HOU L,et al.Geodynamic setting of mineralization of Mississippi Valley-type deposits in worldclass Sichuan-Yunnan-Guizhou Zn-Pb triangle,southwest China:implications from age-dating studies in the past decade and the Sm-Nd age of Jinshachang deposit[J].Journal of Asian Earth Sciences,2015,103:103-114.
[4]张志斌,李朝阳,涂光炽,等.川、滇、黔接壤地区铅锌矿床产出的大地构造演化背景及成矿作用[J].大地构造与成矿学,2006,30(3):343-354.
[5]张长青.中国川滇黔交界地区密西西比型(MVT)铅锌矿床成矿模型[D].北京:中国地质科学院,2008.
[6]吴越.川滇黔地区MVT铅锌矿床大规模成矿作用的时代与机制[D].北京:中国地质大学(北京),2013.
[7]ZHOU J X,BAI J H,HUANG Z L,et al.Geology,isotope geochemistry and geochronology of the Jinshachang carbonate-hosted Pb-Zn deposit,Southwest China[J].Journal of Asian Earth Sciences,2015,98(1):272-284.
[8]韩润生,胡煜昭,王学琨,等.滇东北富锗银铅锌多金属矿集区矿床模型[J].地质学报,2012,86(2):280-294.
[9]HAN R S,LIU C Q,HUANG Z L,et al.Geological features and origin of the Huize carbonate-hosted Zn-Pb-(Ag)District,Yunnan,South China[J].Ore Geology Reviews,2007,31(1):360-383.
[10]ZHOU J X,GAO J G,CHEN D,et al.Ore genesis of the Tianbaoshan carbonate-hosted Pb-Zn deposit,Southwest China:geologic and isotopic(C-H-O-S-Pb)evidence[J].International Geology Review,2013,55(10):1300-1310.
[11]胡耀国.贵州银厂坡银多金属矿床银的赋存状态、成矿物质来源与成矿机制[D].贵阳:中国科学院地球化学研究所,1999.
[12]邓海琳,李朝阳,涂光炽,等.滇东北乐马厂独立银矿床Sr同位素地球化学[J].中国科学:地球科学,1999,29(6):496-503.
[13]ZHOU C X,WEI C S,GUO J Y,et al.The source of metals in the Qilinchang Zn-Pb Deposit,Northeastern Yunnan,China:Pb-Sr isotope constraints[J].Economic Geology,2001,96(3):583-598.
[14]黄智龙,李文博,张振亮,等.云南会泽超大型铅锌矿床成因研究中的几个问题[J].矿物学报,2004,24(2):105-111.
[15]涂首业.四川会理天宝山铅锌矿矿相学特征及意义[D].成都:成都理工大学,2014.
[16]李文博,黄智龙,张冠.云南会泽铅锌矿田成矿物质来源:Pb、S、C、H、O、Sr同位素制约[J].岩石学报,2006,22(10):2567-2580.
[17]张长青,毛景文,余金杰,等.四川甘洛赤普铅锌矿床流体包裹体特征及成矿机制初步探讨[J].岩石学报,2007,23(10):2541-2552.
[18]HU R Z,ZHOU M F.Multiple Mesozoic mineralization events in South China:an introduction to the thematic issue[J].Mineralium Deposita,2012,47(6):579-588.
[19]WANG C M,BAGAS L,LU Y J,et al.Terrane boundary and spatio-temporal distribution of ore deposits in the Sanjiang Tethyan Orogen:insights from zircon Hf-isotopic mapping[J].Earth-Science Reviews,2016,156:39-65.
[20]QIU L,YAN D P,TANG S L,et al.Mesozoic geology of southwestern China:Indosinian foreland overthrusting and subsequent deformation[J].Journal of Asian Earth Sciences,2016,122:91-105.
[21]LO C H,CHUNG S L,LEE T Y,et al.Age of the Emeishan flood magmatism and relations to Permian-Triassic boundary events[J].Earth and Planetary Science Letters,2002,198(3/4):449-458.
[22]付绍洪.扬子地块西南缘铅锌成矿作用与分散元素镉镓锗富集规律[D].成都:成都理工大学,2004.
[23]ZHOU J X,HUANG Z L,BAO G P.Geological and sulfurlead-strontium isotopic studies of the Shaojiwan Pb-Zn deposit,Southwest China:implications for the origin of hydrothermal fluids[J].Journal of Geochemical Exploration,2013,128(2):51-61.
[24]林方成.康滇地轴东缘铅锌矿床铅同位素组成特征及其成因意义[J].特提斯地质,1995(19):131-137.
[25]司荣军.云南省富乐分散元素多金属矿床地球化学研究[M].武汉:中国地质大学出版社,2014.
[26]白俊豪.滇东北金沙厂铅锌矿床地球化学及成因[D].北京:中国科学院大学,2013.
[27]LI W B,HUANG Z L,YIN M D.Isotope geochemistry of the Huize Zn-Pb ore field,Yunnan Province,Southwestern China:implication for the sources of ore fluid and metals[J].Geochemical Journal,2007,41(1):65-81.
[28]ZHOU J X,HUANG Z L,YAN Z F.The origin of the Maozu carbonate-hosted Pb-Zn deposit,southwest China:constrained by C-O-S-Pb isotopic compositions and Sm-Nd isotopic age[J].Journal of Asian Earth Sciences,2013,73(1):39-47.
[29]王超伟,李元,罗海燕,等.云南毛坪铅锌矿床的成因探讨[J].昆明理工大学学报(自然科学版),2009,34(1):7-11.
[30]张云新,吴越,田广,等.云南乐红铅锌矿床成矿时代与成矿物质来源:Rb-Sr和S同位素制约[J].矿物学报,2014,34(3):305-311.
[31]袁波,毛景文,闫兴虎,等.四川大梁子铅锌矿成矿物质来源与成矿机制:硫、碳、氢、氧、锶同位素及闪锌矿微量元素制约[J].岩石学报,2014,30(1):209-220.
[32]李发源.MVT铅锌矿床中分散元素赋存状态和富集机理研究:以四川天宝山、大梁子铅锌矿床为例[D].成都:成都理工大学,2003.
[33]朱赖民,袁海华.四川底苏、大梁子铅锌矿床同位素地球化学特征及成矿物质来源探讨[J].矿物岩石,1995(1):72-79.
[34]ZHU C W,WEN H J,ZHANG Y X,et al.Cadmium and sulfur isotopic compositions of the Tianbaoshan Zn-Pb-Cd deposit,Sichuan Province,China[J].Ore Geology Reviews,2016,76:152-162.
[35]何承真,肖朝益,温汉捷,等.四川天宝山铅锌矿床的锌-硫同位素组成及成矿物质来源[J].岩石学报,2016,32(11):3394-3406.
[36]林孝先.四川汉源地区震旦系灯影组白云岩及其中铅锌矿成矿规律研究[D].成都:成都理工大学,2014.
[37]李伟.四川省宁南县银厂沟-骑骡沟铅锌矿地球化学特征及矿床成因初探[D].成都:成都理工大学,2011.
[38]ZHOU J X,HUANG Z L,LV Z C,et al.Geology,isotope geochemistry and ore genesis of the Shanshulin carbonatehosted Pb-Zn deposit,Southwest China[J].Ore Geology Reviews,2014,63(1):209-225.
[39]张海,孟昌忠,齐有强,等.黔西北云炉河坝铅锌矿集区成矿物质来源:S、Pb同位素制约[J].矿物学报,2016,36(2):271-276.
[40]金翔霖,孟昌忠,冷成彪,等.贵州云炉河坝地区铅锌矿床元素地球化学特征、碳氧同位素组成及其地质意义[J].地球科学与环境学报,2016,38(6):778-790.
[41]ZHOU J X,HUANG Z L,GAO J G,et al.Geological and C-O-S-Pb-Sr isotopic constraints on the origin of the Qingshan carbonate-hosted Pb-Zn deposit,Southwest China[J].International Geology Review,2013,55(7):904-916.
[42]LI B,ZHOU J X,HUANG Z L,et al.Geological,rare earth elemental and isotopic constraints on the origin of the Banbanqiao Zn-Pb deposit,Southwest China[J].Journal of Asian Earth Sciences,2015,111:100-112.
[43]朱路艳,苏文超,沈能平,等.黔西北地区铅锌矿床流体包裹体与硫同位素地球化学研究[J].岩石学报,2016,32(11):3431-3440.
[44]陈兴,薛春纪.西天山乌拉根大规模铅锌成矿中H2S成因:菌生结构和硫同位素组成约束[J].岩石学报,2016,32(5):1301-1314.
[45]WU Y,ZHANG C Q,MAO J W,et al.The genetic relationship between hydrocarbon systems and Mississippi Valley-type Zn-Pb deposits along the SW margin of Sichuan Basin,China[J].International Geology Review,2013,55(8):941-957.
[46]ELSGAARD L,MAI F I,BO B J,et al.Microbial sulfate reduction in deep-sea sediments at the Guaymas Basin hydrothermal vent area:influence of temperature and substrates[J].Geochimica et Cosmochimica Acta,1994,16(58):3335-3343.
[47]MACHEL H G,KROUSE H R,SASSEN R.Products and distinguishing criteria of bacterial and thermochemical sulfate reduction[J].Applied Geochemistry,1995,10(4):373-389.
[48]MACHEL H G.Bacterial and thermochemical sulfate reduction in diagenetic settings-old and new insights[J].Sedimentary Geology,2001,140(1/2):143-175.
[49]YUAN S D,CHOU I M,BURRUSS R C.Disproportionation and thermochemical sulfate reduction reactions in S-H2O-CH4and S-D2O-CH4systems from 200to 340℃at elevated pressures[J].Geochimica et Cosmochimica Acta,2013,118:263-275.
[50]CHANG Z S,LARGE R R,MASLENNIKOV V.Sulfur isotopes in sediment-hosted orogenic gold deposits:evidence for an early timing and a seawater sulfur source[J].Geology,2008,36(12):971-974.
[51]CLAYPOOL G E,HOLSER W T,KAPLAN I R,et al.The age curves of sulfur and oxygen isotopes in marine sulfate and their mutual interpretation[J].Chemical Geology,1980,28:199-260.
[52]张同钢,储雪蕾,张启锐,等.扬子地台灯影组碳酸盐岩中的硫和碳同位素记录[J].岩石学报,2004,20(3):717-724.
[53]SHIELDS G A,STRAUSS H,HOWE S S,et al.Sulphur isotope compositions of sedimentary phosphorites from the basal Cambrian of China:implications for NeoproterozoicCambrian biogeochemical cycling[J].Journal of the Geological Society,1999,156(5):943-955.
[54]OHMOTO H.Systematics of sulfur and carbon isotopes in hydrothermal ore deposits[J].Economic Geology,1972,67(5):551-578.
[55]吴越,张长青,毛景文,等.油气有机质与MVT铅锌矿床的成矿:以四川赤普铅锌矿为例[J].地球学报,2013(4):425-436.
[56]POTRA A,MOYERS A.Constraints on the sources of ore metals in Mississippi Valley-type deposits in central and east Tennessee,USA,using Pb isotopes[J].Ore Geology Reviews,2017,81:201-210.