云南因民铜矿床构造沉积环境及成矿机制研究
|
摘要
因民铜矿床是云南省东川铜矿田中一个重要的矿床,发育有两种矿化类型,分别为赋存于因民组中的稀矿山式铜铁矿体以及赋存于落雪组地层中的东川式铜矿体。文中采用主、微量元素地球化学方法并结合相关热力学计算,探讨含矿岩系因民组及落雪组的岩石特征、沉积环境、构造背景及其铁、铜迁移机制和富集机理。结果表明,因民组及落雪组中以白云岩、硅质白云岩为主,并含少量白云质砂岩,综合100(Fe_2O_3/SiO_2)-100(Al_2O_3/SiO_2)、Fe_2O_3/TiO_2-Al_2O_3/(Al_2O_3+Fe_2O_3)、La-Th-Sc及Th-Co-Zr/10关系图解,指示因民组及落雪组具有大陆边缘区的沉积特点。V/Cr、V/(V+Ni)及Ce/La氧化-还原环境判别图显示,因民组及落雪组整体形成于贫氧过渡状态下的深水-半深水沉积环境。热力学计算表明,在流体迁移过程中,铁、铜主要以氯的络合物形式进行迁移,当成矿流体运移到表层与含硫碱性较还原性水体发生混合时,导致成矿体系温度、Eh和f(S_2)降低,pH值升高,铜、铁络合物发生失稳,先后生成磁铁矿、赤铁矿等氧化物以及黄铁矿、黄铜矿、斑铜矿、辉铜矿等硫化物,在因民组及落雪组中分别形成稀矿山式铜铁矿体和东川式铜矿体。
The Yinmin deposit is an important deposit in the Dongchuan copper ore field in Yunnan Province.It has two mineralization types,one is the Fe-Cu deposit of Xikuangshan type from the Yinmin Formation of the Kunyang Group,the other is the Cu deposit of Dongchuan type from the Luoxue Formation.In this paper,major and trace elemental analyses were combined with thermodynamic calculation to reveal rock characteristics,tectonic setting,sedimentary environment,and mechanism of migration and accumulation of iron and copper.Results show that the Yinmin and Luoxue formations mainly consist of dolomites and siliceous dolomites with dolomitic sandstone as a minor component.Comprehensive analyses of various diagrams,such as 100(Fe_2O_3/SiO_2)-100(Al_2O_3/SiO_2),Fe_2O_3/TiO_2-Al_2O_3/(Al_2O_3+Fe_2O_3),La-Th-Sc and Th-Co-Zr/10graphs,indicate that the contents of carbonate samples from the two formations were consistent with an active continental margin sedimentary system.Discrimination diagrams of redox environment,such as V/Cr,V/(V+Ni)and Ce/La,indicate that the Yinmin and Luoxue formations were deposited in a deep water to semideep-water transitional dysaerobic basin.Thermodynamic calculation results show that iron and copper transported mainly in the form of Cl complex.First,temperature,Eh and f(S_2)decreased while pH increased in the ore-forming system as ore-forming fluid transported to the surface and mixed with the reduced water.Then instability occurred in the complexes of copper and iron.Finally,oxides including hematite and magnetite,sulfides including pyrite,chalcopyrite,bornite and chalcocite changed sequentially with changes in the physical and chemical environment,and formed the ferro-copper and copper ore bodies of the Xikuangshan and Dongchuan types,respectively.
The Yinmin deposit is an important deposit in the Dongchuan copper ore field in Yunnan Province.It has two mineralization types,one is the Fe-Cu deposit of Xikuangshan type from the Yinmin Formation of the Kunyang Group,the other is the Cu deposit of Dongchuan type from the Luoxue Formation.In this paper,major and trace elemental analyses were combined with thermodynamic calculation to reveal rock characteristics,tectonic setting,sedimentary environment,and mechanism of migration and accumulation of iron and copper.Results show that the Yinmin and Luoxue formations mainly consist of dolomites and siliceous dolomites with dolomitic sandstone as a minor component.Comprehensive analyses of various diagrams,such as 100(Fe_2O_3/SiO_2)-100(Al_2O_3/SiO_2),Fe_2O_3/TiO_2-Al_2O_3/(Al_2O_3+Fe_2O_3),La-Th-Sc and Th-Co-Zr/10graphs,indicate that the contents of carbonate samples from the two formations were consistent with an active continental margin sedimentary system.Discrimination diagrams of redox environment,such as V/Cr,V/(V+Ni)and Ce/La,indicate that the Yinmin and Luoxue formations were deposited in a deep water to semideep-water transitional dysaerobic basin.Thermodynamic calculation results show that iron and copper transported mainly in the form of Cl complex.First,temperature,Eh and f(S_2)decreased while pH increased in the ore-forming system as ore-forming fluid transported to the surface and mixed with the reduced water.Then instability occurred in the complexes of copper and iron.Finally,oxides including hematite and magnetite,sulfides including pyrite,chalcopyrite,bornite and chalcocite changed sequentially with changes in the physical and chemical environment,and formed the ferro-copper and copper ore bodies of the Xikuangshan and Dongchuan types,respectively.
引文
[1]李志群,蒋家申,林文达,等.东川式铜矿地球化学研究[J].云南地质,1994,13(1):23-32.
[2]龚琳,何毅特,陈天佑,等.云南东川元古宙裂谷型铜矿[M].北京:冶金工业出版社,1996:78-133.
[3]李天福.东川矿区“小溜口组”地层特征及与因民组的接触关系[J].云南地质,1993,12(1):1-11.
[4]张学诚,陈启良.东川稀矿山火山-喷流沉积含铜铁矿成矿作用初步研究[J].西南矿产地质,1992,21(2):1-9.
[5]黄永平,吴健民,王滋平.东川铜矿田因民组热水沉积岩地质地球化学[J].地质与勘探,1999,35(4):15-18.
[6]叶霖.东川稀矿山式铜矿地球化学研究[D].贵阳:中国科学院地球化学研究所,2004.
[7]陈国达,彭省临,戴塔根,等.云南铜-多金属壳体大地构造成矿学[M].长沙:中南大学出版社,2004:1-423.
[8]李元龙,胡煜昭.云南东川稀矿山式铜铁矿床成矿物质来源的同位素示踪[J].岩石矿物学杂志,2013,32(2):167-179.
[9]吴健民,黄永平.稀矿山式铁铜矿床与奥林匹克坝式铜多金属矿床的对比研究[J].矿产与地质,1998,12(2):79-85.
[10]方维萱,柳玉龙,张守林,等.全球铁氧化物铜金型(IOCG)矿床的3类大陆动力学背景与成矿模式[J].西北大学学报(自然科学版),2009,39(3):404-413.
[11]方维萱,杨新雨,郭茂华,等.云南白锡腊碱性钛铁质辉长岩类与铁氧化物铜金型矿床关系研究[J].大地构造与成矿学,2013,37(2):242-261.
[12]方维萱.论扬子地块西缘元古宙铁氧化物铜金型矿床与大地构造演化[J].大地构造与成矿学,2014,38(4):733-757.
[13]ZHAO X F,ZHOU M F,LI J W,et al.Late Paleoproterozoic to early Mesoproterozoic Dongchuan Group in Yunnan,SW China:implications for tectonic evolution of the Yangtze Block[J].Precambrian Research,2010,182(1/2):57-69.
[14]谢家荣.云南矿产概论[J].地质论评,1941,6(增刊):1-42.
[15]李洪谟,王尚文.东川铜矿地质初报[J].地质论评,1941,6(增刊):43-72.
[16]MENG H,CHANG H,HSU S,et al.Geology of the Tungchuan district,northern Yunnan[J].Academia Sinica,1948,1052:44-51.
[17]桂林冶金地质研究所变质岩铜矿专题组.东川铜矿的地层岩石特征及其与成矿的关系[J].地质与勘探,1975(4):18-26.
[18]WALTER M R.Stromatolites[M].Amsterdam:Elsevier Scientific Publication Co.1976,376-379.
[19]冉崇英,吴鹏.东川—易门式铜矿床成矿作用研究的几个问题[J].大地构造与成矿学,2014,38(4):848-854.
[20]周新华,李献华,邱华宁.云南东川铜矿40 Ar/39 Ar成矿年代研究[M]∥赵振华,涂光炽.中国超大型矿床Ⅱ.北京:科学出版社,2003:204-223.
[21]高剑峰,陆建军,赖鸣远,等.岩石样品中微量元素的高分辨率等离子质谱分析[J].南京大学学报(自然科学版),2003,39(6):844-850.
[22]黄虎,杜远生,黄志强,等.桂西晚古生代硅质岩地球化学特征及其对右江盆地构造演化的启示[J].中国科学:地球科学,2013,43(2):304-316.
[23]MURRAY R W,JONES D L,GERLACH D C,et al.Rare earth elements as indicators of different marine depositional environments in chert and shale[J].Geology,1990,18(3):268.
[24]MURRAY R W.Chemical criteria to identify the depositional environment of chert:general principles and applications[J].Sedimentary Geology,1994,90(3/4):213-232.
[25]GROMET L P,HASKIN L A,KOROTEV R L,et al.The“North American shale composite”:its compilation,major and trace element characteristics[J].Geochimica et Cosmochimica Acta,1985,48(12):2469-2482.
[26]ROLLISON H R,杨学明,杨晓勇,等.岩石地球化学[M].合肥:中国科技大学出版社,2000.
[27]WRIGHT J,SEYMOUR R S,SHAW H F,et al.REE and Nd isotopes in conodont apatite:variations with geological age and depositional environment[J].Special Paper of the Geological Society of America,1984,196:325-340.
[28]黄喜峰,钱壮志,逯东霞,等.贺兰山中南段奥陶系米钵山组的沉积环境与构造背景分析[J].地球学报,2009,30(1):65-71.
[29]BHATIA M R,CROOK K A.Trace element characteristics of grey wackes and tectonic setting discrimination of sedimentary basins[J].Contributions to Mineralogy and Petrology,1986,92(2):181-193.
[30]龚琳.试论川滇古大陆边缘裂谷带及铜矿成矿作用[J].矿产与勘查,1991(4):1-7.
[31]杨兴莲,朱茂炎,赵元龙,等.黔东前寒武纪—寒武纪转换时期微量元素地球化学特征研究[J].地质学报,2007,81(10):1391-1397.
[32]HATCH J R,LEVENTHAL J S.Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian(Missourian)Stark Shale Member of the Dennis Limestone,Wabaunsee County,Kansas,USA[J].Chemical Geology,1992,99(1/2/3):65-82.
[33]JONES B,MANNING D A C.Comparison of geochemical indices used for the interpretation of palaeoredox conditions in ancient mudstones[J].Chemical Geology,1994,111(1/2/3/4):111-129.
[34]RIMMER S M,THOMPSON J A,GOODNIGHT S A,et al.Multiple controls on the preservation of organic matter in Devonian-Mississippian marine black shales:geochemical and petrographic evidence[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2004,215(1/2):125-154.
[35]林传仙,白正华,张哲儒.矿物及有关化合物热力学数据手册[M].北京:科学出版社,1985:1-355.
[36]吴健民,黄永平.扬子地台西缘稀矿山式铁铜矿床成矿条件与火山-喷流成矿作用研究[J].矿床地质,1998,16(增刊):1-4.
[37]王玉荣,卢家烂,樊文岭.高温气热溶液中铁元素迁移形式的初步实验研究[M].北京:科学出版社,1979:78-79.
[38]冉崇英.论东川—易门式铜矿的矿源与成矿流体[J].昆明理工大学学报(理工版),1989,14(4):12-20.
[39]BARNES H L.Solubilities of ore minerals[J].Geochemistry of Hydrothermal Ore Deposits,1979,36(2):404-460.
[40]SIMON A C,PETTKE T,CANDELA P A,et al.Copper partitioning in a melt-vapor-brine-magnetite-pyrrhotite assemblage[J].Geochimica et Cosmochimica Acta,2006,70(22):5583-5600.
[41]FRANK M R,SIMON A C,PETTKE T,et al.Gold and copper partitioning in magmatic-hydrothermal systems at 800℃and 100 MPa[J].Geochimica et Cosmochimica Acta,2011,75(9):2470-2482.
[42]MOUNTAIN B W,SEWARD T M.Hydrosulfide/sulfide complexes of copper(I):experimental confirmation of the stoichiometry and stability of Cu(HS)-2to elevated temperatures[J].Geochimica et Cosmochimica Acta,2003,67(16):3005-3014.
[43]MOUNTAIN B W,SEWARD T M.The hydrosulphide/sul-phide complexes of copper(I):experimental determination of stoichiometry and stability at 22℃and reassessment of high temperature data[J].Geochimica et Cosmochimica Acta,1999,63(1):11-29.
[44]ZAJACZ Z,SEO J H,CANDELA P A,et al.The solubility of copper in high-temperature magmatic vapors:aquest for the significance of various chloride and sulfide complexes[J].Geochimica et Cosmochimica Acta,2011,75(10):2811-2827.
[45]HOOPER E C D.Fluid migration along growth faults in compacting sediments[J].Journal of Petroleum Geology,1991,14(Suppl 1):161-180.
[46]LIU W,MCPHAIL D C.Thermodynamic properties of copper chloride complexes and copper transport in magmatic-hydrothermal solutions[J].Chemical Geology,2005,221(1):21-39.
[47]陈艳,张招崇.夕卡岩型铁矿的铁质来源与迁移富集机理探讨[J].岩矿测试,2012,31(5):889-897.
[48]张德会,赵伦山.地球化学[M].北京:地质出版社,2013:384-423.
[49]张德会.流体的沸腾和混合在热液成矿中的意义[J].地球科学进展,1997,12(6):546-552.
[50]华仁民.东川式层状铜矿的沉积-改造成因[J].矿床地质,1989,8(2):3-13.
[51]张艳,韩润生,吴鹏,等.陆相砂岩型铜矿床矿物组合分带的logfO2-logfS2相图:以云南大姚六苴铜矿床为例[J].矿物岩石,2013,33(2):35-42.
(1)有色金属矿产地质调查中心.东川铜矿因民铜矿区基础地质工作、地质综合研究与找矿预测总结报告.2009.
[2]龚琳,何毅特,陈天佑,等.云南东川元古宙裂谷型铜矿[M].北京:冶金工业出版社,1996:78-133.
[3]李天福.东川矿区“小溜口组”地层特征及与因民组的接触关系[J].云南地质,1993,12(1):1-11.
[4]张学诚,陈启良.东川稀矿山火山-喷流沉积含铜铁矿成矿作用初步研究[J].西南矿产地质,1992,21(2):1-9.
[5]黄永平,吴健民,王滋平.东川铜矿田因民组热水沉积岩地质地球化学[J].地质与勘探,1999,35(4):15-18.
[6]叶霖.东川稀矿山式铜矿地球化学研究[D].贵阳:中国科学院地球化学研究所,2004.
[7]陈国达,彭省临,戴塔根,等.云南铜-多金属壳体大地构造成矿学[M].长沙:中南大学出版社,2004:1-423.
[8]李元龙,胡煜昭.云南东川稀矿山式铜铁矿床成矿物质来源的同位素示踪[J].岩石矿物学杂志,2013,32(2):167-179.
[9]吴健民,黄永平.稀矿山式铁铜矿床与奥林匹克坝式铜多金属矿床的对比研究[J].矿产与地质,1998,12(2):79-85.
[10]方维萱,柳玉龙,张守林,等.全球铁氧化物铜金型(IOCG)矿床的3类大陆动力学背景与成矿模式[J].西北大学学报(自然科学版),2009,39(3):404-413.
[11]方维萱,杨新雨,郭茂华,等.云南白锡腊碱性钛铁质辉长岩类与铁氧化物铜金型矿床关系研究[J].大地构造与成矿学,2013,37(2):242-261.
[12]方维萱.论扬子地块西缘元古宙铁氧化物铜金型矿床与大地构造演化[J].大地构造与成矿学,2014,38(4):733-757.
[13]ZHAO X F,ZHOU M F,LI J W,et al.Late Paleoproterozoic to early Mesoproterozoic Dongchuan Group in Yunnan,SW China:implications for tectonic evolution of the Yangtze Block[J].Precambrian Research,2010,182(1/2):57-69.
[14]谢家荣.云南矿产概论[J].地质论评,1941,6(增刊):1-42.
[15]李洪谟,王尚文.东川铜矿地质初报[J].地质论评,1941,6(增刊):43-72.
[16]MENG H,CHANG H,HSU S,et al.Geology of the Tungchuan district,northern Yunnan[J].Academia Sinica,1948,1052:44-51.
[17]桂林冶金地质研究所变质岩铜矿专题组.东川铜矿的地层岩石特征及其与成矿的关系[J].地质与勘探,1975(4):18-26.
[18]WALTER M R.Stromatolites[M].Amsterdam:Elsevier Scientific Publication Co.1976,376-379.
[19]冉崇英,吴鹏.东川—易门式铜矿床成矿作用研究的几个问题[J].大地构造与成矿学,2014,38(4):848-854.
[20]周新华,李献华,邱华宁.云南东川铜矿40 Ar/39 Ar成矿年代研究[M]∥赵振华,涂光炽.中国超大型矿床Ⅱ.北京:科学出版社,2003:204-223.
[21]高剑峰,陆建军,赖鸣远,等.岩石样品中微量元素的高分辨率等离子质谱分析[J].南京大学学报(自然科学版),2003,39(6):844-850.
[22]黄虎,杜远生,黄志强,等.桂西晚古生代硅质岩地球化学特征及其对右江盆地构造演化的启示[J].中国科学:地球科学,2013,43(2):304-316.
[23]MURRAY R W,JONES D L,GERLACH D C,et al.Rare earth elements as indicators of different marine depositional environments in chert and shale[J].Geology,1990,18(3):268.
[24]MURRAY R W.Chemical criteria to identify the depositional environment of chert:general principles and applications[J].Sedimentary Geology,1994,90(3/4):213-232.
[25]GROMET L P,HASKIN L A,KOROTEV R L,et al.The“North American shale composite”:its compilation,major and trace element characteristics[J].Geochimica et Cosmochimica Acta,1985,48(12):2469-2482.
[26]ROLLISON H R,杨学明,杨晓勇,等.岩石地球化学[M].合肥:中国科技大学出版社,2000.
[27]WRIGHT J,SEYMOUR R S,SHAW H F,et al.REE and Nd isotopes in conodont apatite:variations with geological age and depositional environment[J].Special Paper of the Geological Society of America,1984,196:325-340.
[28]黄喜峰,钱壮志,逯东霞,等.贺兰山中南段奥陶系米钵山组的沉积环境与构造背景分析[J].地球学报,2009,30(1):65-71.
[29]BHATIA M R,CROOK K A.Trace element characteristics of grey wackes and tectonic setting discrimination of sedimentary basins[J].Contributions to Mineralogy and Petrology,1986,92(2):181-193.
[30]龚琳.试论川滇古大陆边缘裂谷带及铜矿成矿作用[J].矿产与勘查,1991(4):1-7.
[31]杨兴莲,朱茂炎,赵元龙,等.黔东前寒武纪—寒武纪转换时期微量元素地球化学特征研究[J].地质学报,2007,81(10):1391-1397.
[32]HATCH J R,LEVENTHAL J S.Relationship between inferred redox potential of the depositional environment and geochemistry of the Upper Pennsylvanian(Missourian)Stark Shale Member of the Dennis Limestone,Wabaunsee County,Kansas,USA[J].Chemical Geology,1992,99(1/2/3):65-82.
[33]JONES B,MANNING D A C.Comparison of geochemical indices used for the interpretation of palaeoredox conditions in ancient mudstones[J].Chemical Geology,1994,111(1/2/3/4):111-129.
[34]RIMMER S M,THOMPSON J A,GOODNIGHT S A,et al.Multiple controls on the preservation of organic matter in Devonian-Mississippian marine black shales:geochemical and petrographic evidence[J].Palaeogeography,Palaeoclimatology,Palaeoecology,2004,215(1/2):125-154.
[35]林传仙,白正华,张哲儒.矿物及有关化合物热力学数据手册[M].北京:科学出版社,1985:1-355.
[36]吴健民,黄永平.扬子地台西缘稀矿山式铁铜矿床成矿条件与火山-喷流成矿作用研究[J].矿床地质,1998,16(增刊):1-4.
[37]王玉荣,卢家烂,樊文岭.高温气热溶液中铁元素迁移形式的初步实验研究[M].北京:科学出版社,1979:78-79.
[38]冉崇英.论东川—易门式铜矿的矿源与成矿流体[J].昆明理工大学学报(理工版),1989,14(4):12-20.
[39]BARNES H L.Solubilities of ore minerals[J].Geochemistry of Hydrothermal Ore Deposits,1979,36(2):404-460.
[40]SIMON A C,PETTKE T,CANDELA P A,et al.Copper partitioning in a melt-vapor-brine-magnetite-pyrrhotite assemblage[J].Geochimica et Cosmochimica Acta,2006,70(22):5583-5600.
[41]FRANK M R,SIMON A C,PETTKE T,et al.Gold and copper partitioning in magmatic-hydrothermal systems at 800℃and 100 MPa[J].Geochimica et Cosmochimica Acta,2011,75(9):2470-2482.
[42]MOUNTAIN B W,SEWARD T M.Hydrosulfide/sulfide complexes of copper(I):experimental confirmation of the stoichiometry and stability of Cu(HS)-2to elevated temperatures[J].Geochimica et Cosmochimica Acta,2003,67(16):3005-3014.
[43]MOUNTAIN B W,SEWARD T M.The hydrosulphide/sul-phide complexes of copper(I):experimental determination of stoichiometry and stability at 22℃and reassessment of high temperature data[J].Geochimica et Cosmochimica Acta,1999,63(1):11-29.
[44]ZAJACZ Z,SEO J H,CANDELA P A,et al.The solubility of copper in high-temperature magmatic vapors:aquest for the significance of various chloride and sulfide complexes[J].Geochimica et Cosmochimica Acta,2011,75(10):2811-2827.
[45]HOOPER E C D.Fluid migration along growth faults in compacting sediments[J].Journal of Petroleum Geology,1991,14(Suppl 1):161-180.
[46]LIU W,MCPHAIL D C.Thermodynamic properties of copper chloride complexes and copper transport in magmatic-hydrothermal solutions[J].Chemical Geology,2005,221(1):21-39.
[47]陈艳,张招崇.夕卡岩型铁矿的铁质来源与迁移富集机理探讨[J].岩矿测试,2012,31(5):889-897.
[48]张德会,赵伦山.地球化学[M].北京:地质出版社,2013:384-423.
[49]张德会.流体的沸腾和混合在热液成矿中的意义[J].地球科学进展,1997,12(6):546-552.
[50]华仁民.东川式层状铜矿的沉积-改造成因[J].矿床地质,1989,8(2):3-13.
[51]张艳,韩润生,吴鹏,等.陆相砂岩型铜矿床矿物组合分带的logfO2-logfS2相图:以云南大姚六苴铜矿床为例[J].矿物岩石,2013,33(2):35-42.
(1)有色金属矿产地质调查中心.东川铜矿因民铜矿区基础地质工作、地质综合研究与找矿预测总结报告.2009.