江西武山花岗闪长斑岩中黑云母成分特征及其成岩成矿意义
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摘要
江西武山花岗闪长斑岩与矽卡岩铜矿在成因上密切相关,通过对其中的黑云母进行的岩相学观察和详细的矿物化学分析来探讨黑云母的形成条件及其成岩成矿意义。电子探针分析结果表明,武山花岗闪长斑岩中的黑云母富镁贫铁低铝高钛,属镁质黑云母。其AlⅥ为0.03~0.19,w(ΣFeO)/w(ΣFeO+MgO)为0.531~0.567,w(MgO)为12.80%~14.06%,指示武山花岗闪长斑岩属壳幔混源的I型花岗岩。黑云母结晶的温度为720℃~750℃,logfO2为-11.6~-12.5,压力为86 MPa~103 MPa,对应的侵位深度为2.84 km~3.39 km,表明该岩体形成于相对高温较浅环境,具有较大成矿潜力,有利于武山铜矿的形成。
Wushan skarn copper deposit is associated with Wushan granodiorite in genesis.In this paper,we petrographic and mineralogical characteristics of the biotites in Wushan granodiorite are investigated,and its forming conditions and the significance for petrogenesis and mineralization are discussed.Electron microprobe analysis(EPMA) shows that the biotites,which belong to Mg-biotites,are relatively rich in Mg and Ti and poor in Fe and Al.The ionic coefficient of AlⅥ is 0.03~0.19,the ratios of w(ΣFeO)/w(ΣFeO+MgO)are 0.531~0.567,and the contents of MgO are 12.80%~14.06%.These characteristics implicate that Wushan granodiorite belongs to I-type granite.The crystallization temperature(T) and oxygen fugacity(logfO2) of the biotites are 720 ℃~750 ℃ and-11.6~-12.5,respectively.The solidification pressure(P) of the biotites is 86 MPa~103 MPa,corresponding to solidification depth(H) of 2.84 km~3.39 km.These crystallization conditions indicate that Wushan granodiorite,which was formed in high temperature and oxygen fugacity,has a large mineralization potentiality and is benefit for the formation of Wushan copper deposit.
Wushan skarn copper deposit is associated with Wushan granodiorite in genesis.In this paper,we petrographic and mineralogical characteristics of the biotites in Wushan granodiorite are investigated,and its forming conditions and the significance for petrogenesis and mineralization are discussed.Electron microprobe analysis(EPMA) shows that the biotites,which belong to Mg-biotites,are relatively rich in Mg and Ti and poor in Fe and Al.The ionic coefficient of AlⅥ is 0.03~0.19,the ratios of w(ΣFeO)/w(ΣFeO+MgO)are 0.531~0.567,and the contents of MgO are 12.80%~14.06%.These characteristics implicate that Wushan granodiorite belongs to I-type granite.The crystallization temperature(T) and oxygen fugacity(logfO2) of the biotites are 720 ℃~750 ℃ and-11.6~-12.5,respectively.The solidification pressure(P) of the biotites is 86 MPa~103 MPa,corresponding to solidification depth(H) of 2.84 km~3.39 km.These crystallization conditions indicate that Wushan granodiorite,which was formed in high temperature and oxygen fugacity,has a large mineralization potentiality and is benefit for the formation of Wushan copper deposit.
引文
[1]顾连兴.江西武山与华南型块状硫化物矿床伴生的燕山期侵入岩[J].岩石学报,1987,(1):64-76.
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[4]蒋少涌,李亮,朱碧,等.江西武山铜矿区花岗闪长斑岩的地球化学和Sr-Nd-Hf同位素组成及成因探讨[J].岩石学报,2008,24(8):1 679-1 690.
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[12]Lalonde A E,Bernard P.Composition and color of biotite from granites:two useful pro-perties in the characterization of plutonic suitesfrom the Hepburn internal zone of Wopmay orog-en,Northwest Territories[J].Canad Mineralogist,1993,31:203-217.
[13]Abdel-Rahman AM.Nature of biotites from alkaline,calc-alkaline,and peraluminous magmas[J].Journal of Petrology,1994,35:525-541.
[14]Hecht L.The chemical composition of biotite as an indicator of magmatic fractionation and metasomatism in Sn-specialised granites of theFichtelgebirge(NW Bohemian Massif,Germany).In:Seltmann R.,Kampf H.&M ller P.(Eds.):Metallogeny of collisional orogens[J].Czech Geol Surv,1994,295-300.
[15]Abdel-Fattah MA.Nature of biotites from alkaline,calc-alkaline,and peraluminous magmas[J].Jour Petrol,1994,35:525-541.
[16]Abdel-Fattah MA.Discussion on the comment on nature of biotites in alkaline,calc-alkaline,and peraluminous magmas[J].Jour Petrol,1996,37:1 031-1 035.
[17]林文蔚,彭丽君.由电子探针分析数据估算角闪石、黑云母中的Fe3+、Fe2+[J].长春地质学院院报,1994,24(2):155-162.
[18]Stone D.Temperature and pressure variations in suites of Archean felsic plutonic rocks,Bere-ns river area,northwest superior province,Ontario,Cananda[J].The Canadian Mineralogist,2000,38:455-470.
[19]Foster M D.Interpretation of composition of trioctahedral micas[J].U S Geol Surv Prof Paper,1960,354B:1-49.
[20]Deer W A,Howie R A,Zussman J.An introduction to the rock-forming minerals[M].UK:Longman Group UK Ltd,1966.
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[22]Albuquerque A C.Geochemistry of biotites from granitic rocks,northern Portugal[J].Geochim Cosmoehim Acta,1973,37:1 779-1 802.
[23]Noyes H J,Wones D R,Frey F A.A tale of two plutons:petrographic and mineralogic constraints on the petro-genesis of the Red Lakeand Eagle Peak plutons,Central Sierra Nevada,California[J].The Journal of Geology,1983,91(4):353-378.
[24]Wones D R.Significance of the assemblage titanite+magnetite+quartz in granitic rocks[J].Am Mineral,1989,74:744-749.
[25]Etsuo Uchida,Sho Endo,Mitsutoshi Makino.Relationship Between Solidification Depth of Granitic Rocks and Formation of HydrothermalOre Deposits[J].Resource Geology,2007,57(1):47-56.
[26]Whalen JBCB.Opaque mineralogy and mafic mineral chemistry of I-and S-type granites of Lachlan fold belt,southeast Australia[J].Amer-ican Mineralogist,1988,73(3):281-296.
[27]周作侠.湖北丰山洞岩体成因探讨[J].岩石学报,1986,2(1):59-70.
[28]Ding X,Jiang S Y,Zhao K D,et al.In-situ U-Pb SIMS dating and trace element(EMPA)composition of zircon from a granodiorite por-phyry in the Wushan copper deposit,China[J].Contri Mineral Petrol,2006,86:29-44.
[29]Wyborn D,Sun S S.Sulphur-undersafurated magmatism:A key factor for generating magma-related copper-gold deposits[J].AGSO Re-search Newsletter,1994,21:7-8.
[30]Sun W D,Arculus R J,Kamenetsky V S,et al.Release of gold-bearing fluids in convergent margin magmas prompted by ma-gnetite crys-tallization[J].Nature,2004,431:975-978.
[2]包家宝,汤树清,余志庆.江西铜矿地质[M].南昌:江西科学技术出版社,2002,75-85.
[3]丁昕,蒋少涌,倪培,等.江西武山和永平铜矿含矿花岗质岩体锆石SIMS U-Pb年代学研究[J].高校地质学报,2005,11(3):383-389.
[4]蒋少涌,李亮,朱碧,等.江西武山铜矿区花岗闪长斑岩的地球化学和Sr-Nd-Hf同位素组成及成因探讨[J].岩石学报,2008,24(8):1 679-1 690.
[5]季绍新,王文斌,邢文臣,等.江西九瑞地区两个成矿系列的铜矿床[J].矿床地质,1989,8(2):14-24.
[6]黄恩邦,张迺堂,罗钊生.城门山、武山铜矿床成因[J].矿床地质,1990,9(4):291-300.
[7]崔彬,杨明银,詹朝阳.武山铜矿北矿带黄铁矿的成因矿物学研究[J].地质与勘探,2002,38(5):44-48.
[8]Wones D P,Eugeter H P.Stability of biotite:experiment,theory,and application[J].The American Mineralogist,1965,50:1 228-1 272.
[9]Burkhard D J M.Temperature and redox path of biotite-bearing intrusives:a method of esti-mation applied to S-and I-type granites fromAustralia[J].Earth Planet Sci Lett,1991,104:89-98.
[10]Barriére M,Cotton J.Biotites and associated minerals as markers of magmatic fractionation and deuteric equilibration in granites[J].ContrMineral Petrology,1979,70:183-192.
[11]El Sheshtawi Y A,Salem A K A,Aly M M.The geochemistry of ferrous biotite and petrogenesis of Wadi El-Sheikh granitoid rocks South-western Sinai,Egypt[J].African Earth Sci,1993,16(4):489-498.
[12]Lalonde A E,Bernard P.Composition and color of biotite from granites:two useful pro-perties in the characterization of plutonic suitesfrom the Hepburn internal zone of Wopmay orog-en,Northwest Territories[J].Canad Mineralogist,1993,31:203-217.
[13]Abdel-Rahman AM.Nature of biotites from alkaline,calc-alkaline,and peraluminous magmas[J].Journal of Petrology,1994,35:525-541.
[14]Hecht L.The chemical composition of biotite as an indicator of magmatic fractionation and metasomatism in Sn-specialised granites of theFichtelgebirge(NW Bohemian Massif,Germany).In:Seltmann R.,Kampf H.&M ller P.(Eds.):Metallogeny of collisional orogens[J].Czech Geol Surv,1994,295-300.
[15]Abdel-Fattah MA.Nature of biotites from alkaline,calc-alkaline,and peraluminous magmas[J].Jour Petrol,1994,35:525-541.
[16]Abdel-Fattah MA.Discussion on the comment on nature of biotites in alkaline,calc-alkaline,and peraluminous magmas[J].Jour Petrol,1996,37:1 031-1 035.
[17]林文蔚,彭丽君.由电子探针分析数据估算角闪石、黑云母中的Fe3+、Fe2+[J].长春地质学院院报,1994,24(2):155-162.
[18]Stone D.Temperature and pressure variations in suites of Archean felsic plutonic rocks,Bere-ns river area,northwest superior province,Ontario,Cananda[J].The Canadian Mineralogist,2000,38:455-470.
[19]Foster M D.Interpretation of composition of trioctahedral micas[J].U S Geol Surv Prof Paper,1960,354B:1-49.
[20]Deer W A,Howie R A,Zussman J.An introduction to the rock-forming minerals[M].UK:Longman Group UK Ltd,1966.
[21]Henry D J,Guidotti C V,Thomoson J A.The Tisaturation surface for low-to-medium pressure metapelitic biotites:Implications for geo-thermonmetry and Ti-substitution mechanisms[J].Am Mineral,90:316-328.
[22]Albuquerque A C.Geochemistry of biotites from granitic rocks,northern Portugal[J].Geochim Cosmoehim Acta,1973,37:1 779-1 802.
[23]Noyes H J,Wones D R,Frey F A.A tale of two plutons:petrographic and mineralogic constraints on the petro-genesis of the Red Lakeand Eagle Peak plutons,Central Sierra Nevada,California[J].The Journal of Geology,1983,91(4):353-378.
[24]Wones D R.Significance of the assemblage titanite+magnetite+quartz in granitic rocks[J].Am Mineral,1989,74:744-749.
[25]Etsuo Uchida,Sho Endo,Mitsutoshi Makino.Relationship Between Solidification Depth of Granitic Rocks and Formation of HydrothermalOre Deposits[J].Resource Geology,2007,57(1):47-56.
[26]Whalen JBCB.Opaque mineralogy and mafic mineral chemistry of I-and S-type granites of Lachlan fold belt,southeast Australia[J].Amer-ican Mineralogist,1988,73(3):281-296.
[27]周作侠.湖北丰山洞岩体成因探讨[J].岩石学报,1986,2(1):59-70.
[28]Ding X,Jiang S Y,Zhao K D,et al.In-situ U-Pb SIMS dating and trace element(EMPA)composition of zircon from a granodiorite por-phyry in the Wushan copper deposit,China[J].Contri Mineral Petrol,2006,86:29-44.
[29]Wyborn D,Sun S S.Sulphur-undersafurated magmatism:A key factor for generating magma-related copper-gold deposits[J].AGSO Re-search Newsletter,1994,21:7-8.
[30]Sun W D,Arculus R J,Kamenetsky V S,et al.Release of gold-bearing fluids in convergent margin magmas prompted by ma-gnetite crys-tallization[J].Nature,2004,431:975-978.
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