东天山尾亚钒钛磁铁矿矿床岩石地球化学特征及成矿作用
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摘要
尾亚矿床是东天山铜镍硫化物矿床—钒钛磁铁矿床—磁铁矿(钴)矿床成矿系列的重要组成部分。本文以野外宏观地质现象为基础,通过对尾亚矿床开展岩石地球化学研究,认为具有Nb,Ta负异常,Ce正异常,w(La)/w(Nb)比均大于1,w(Nb)/w(U)较小(<30),w(Th)PM/w(Ta)PM较大(大多数大于1)等特征,说明成矿岩浆起源于受俯冲物质影响较小的亏损型地幔,在侵入地壳过程中,发生地壳物质混染。同时,对矿石中的磁铁矿进行氧同位素测试,δ18OSMOW>6‰,也说明受到地壳物质的混染。为弄清贯入式矿体的成因,尝试从氧化物熔体不混溶的角度探讨这种矿体的成矿作用。研究结果表明:就尾亚矿床而言,地壳物质混染、偏基性矿物分离结晶、岩浆体系P含量增加和较高氧逸度等因素,共同促使氧化物熔体不混溶作用的发生,为贯入式矿体的形成提供有利条件;尾亚矿区内黑云母辉长岩中锆石U-Pb成岩年龄为(253.16±0.8)Ma,形成于晚二叠世,指示成岩构造环境为准噶尔板块和塔里木板块聚合之后的后碰撞伸展阶段。
Weiya deposit is an important part of Cu-Ni sulphide-titanomagnetite(vanadium)-magnetite(cobalt) mineralization system in Eastern Tianshan. Based on detailed observation, geochemical studies of rocks associated with the deposit show that it is characterized by depletion of Nb and Ta, enrichment of Ce, w(La)/w(Nb)>1, w(Nb)/w(U)>30, w(Th)PM/w(Ta)PM ratio>1. These features, combined with δ18OSMOW>6‰, indicate that the ore-bearing magma was derived from depleted mantle, and contaminated by crustal materials in the ascent to the surface. In the evolution of magma, mafic minerals fractional crystallization, addition of P element, and high f(O2), oxide melts immiscibility conduce the veined oxide ore body under tectonization. LA-ICPMS isotopic dating of zircon from biotite-gabbro is (253.16±0.8) Ma, which means the diagenetic age of late Permian and represents an extensional setting of post-collisional between the Junggar plate and Tarim plate.
Weiya deposit is an important part of Cu-Ni sulphide-titanomagnetite(vanadium)-magnetite(cobalt) mineralization system in Eastern Tianshan. Based on detailed observation, geochemical studies of rocks associated with the deposit show that it is characterized by depletion of Nb and Ta, enrichment of Ce, w(La)/w(Nb)>1, w(Nb)/w(U)>30, w(Th)PM/w(Ta)PM ratio>1. These features, combined with δ18OSMOW>6‰, indicate that the ore-bearing magma was derived from depleted mantle, and contaminated by crustal materials in the ascent to the surface. In the evolution of magma, mafic minerals fractional crystallization, addition of P element, and high f(O2), oxide melts immiscibility conduce the veined oxide ore body under tectonization. LA-ICPMS isotopic dating of zircon from biotite-gabbro is (253.16±0.8) Ma, which means the diagenetic age of late Permian and represents an extensional setting of post-collisional between the Junggar plate and Tarim plate.
引文
[1]宋谢炎,王玉兰,张正阶,等.层状侵入体韵律层理形成过程的定量模拟—以四川攀枝花层状岩体为例[J].地质学报,1999,73(1):37-46.SONG Xieyan,WANG Yulan,ZHANG Zhengjie,et al.Quantitative simulation of formation of the rhythmic layering in layered intrusions—A case study of the Panzhihua layered intrusion,Sichuan[J].Acta Geologica Sinica,1999,73(1):37-46.
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[8]李玫,王玉往,王京彬,等.新疆尾亚地区岩浆混合作用的年代学证据[J].中国地质,2010,37(1):39-47.LI Mei,WANG Yuwang,WANG Jingbin,et al.Zircon U-Pb chronologic evidence for magma mixing in the Weiya ore district,Xinjiang[J].Geology in China,2010,37(1):39-47.
[9]李锦轶,王克卓,李文铅,等.东天山晚古生代以来大地构造与矿产勘查[J].新疆地质,2002,20(4):295-301.LI Jinyi,WANG Kezhang,LI Wenqian,et al.Tectonic evolution since the late paleozoic and mineral preospecting in eastern Tianshan,NW China[J].Xinjiang Geology,2002,20(4):295-301.
[10]王玉往,王京彬,王莉娟,等.新疆尾亚钒钛磁铁矿——个岩浆分异-贯入-热液型复成因矿床[J].矿床地质,2005,24(4):349-360.WANG Yuwang,WANG Jingbin,WANG Lijuan,et al.Weiya vanadium-bearing titanomagnetite deposit in Xinjiang:A polygenetic magmatic differentiation-magmatic injection-magmatic hydrothermal deposit[J].Mineral Deposits,2005,24(4):349-360.
[11]Zhang Z Z,Gu L X,Wu C Z,et a1.Zircon SHRIMP dating for the Weiya pluton,eastern Tianshan:Its geological impfications[J].Acta Geologica Sinica:English Edidon,2005,79(4):481-490.
[12]Wood D A,Joron J L,Treuil M.A reappraisal of the use of trace elements to classify and discriminate between magma series erupted in different tectonic settings[J].Earth Planet Sci Let,1979,45:326-336.
[13]Saunders A D,Norry M J,Tarney J.Origin of MORB and chemically-depleted mantle reservoirs:trace element constraints[J].Journal of Petrology,Special Volume,1988:415-445.
[14]Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,London,Special Publication,1989,42:313-345.
[15]董云鹏,周鼎武,张国伟.东秦岭富水基性杂岩体地球化学特征及其形成环境[J].地球化学,1997,16(3):79-87.DONG Yunpeng,ZHOU Dingwu,ZHANG Guowei.Geochemistry and formation setting of Fushui complex,eastern Qinling[J].Geochemistry,1997,16(3):79-87.
[16]Sun S S,Nesbitt R W.Petrogenesis of Archaean ultrabasic and basic volcanic:Evidence from the rare earth elements[J].Contrib.Mineral.Petro.,1978,165:301-325.
[17]Weaver B L,Tarney J.Thermal aspects of komatiite generation and greenstone belt models[J].Nature,1979,279:689-692.
[18]Kyser T K,CarmeronW E,Nisbet E G.Boninite petrogenesis and alteration history:Constraints from stable isotope compositions of boninites from Caoe Vogel,New Caledonia and Cyprus[J].Contri Mineral Petrol,1986,93:222-226.
[19]Harmon R S,Kempton P D,Stosch H G,et al.18O/16O ratios in anhydrous spinel lherzolite xenoliths from the Sdhavaryn-Tsaram vo lcano,Mongolia[J].Earth Planet Sci Lett,1987,81:193-202.
[20]Mattey D,Lowry D,M cpherson C.Oxygen isotope composition of mantle periotite[J].Earth Planet Sci L ett.,1994,128:231-241.
[21]Neal C R,Mahoney J J,Chazey W J.Mantle sources and the highly variable role of continental lithosphere in basalt petrogenesis of the Kerguelen Plateau and Broken Ridge LIP:results from ODP Leg 183[J].J Petrol,2002,43:1177-1205.
[22]Chai F M,Zhang Z C,Mao J W,et al.Geology,petrology and geochemistry of the Baishiquan Ni-Cu-bearing mafic-ultramaficintrusions in Xin jiang,NW China:Implications for tectonics and genesis of ores[J].Journal of Asian Earth Sciences,2008,32:218-235.
[23]唐冬梅,秦克章,孙赫,等.天宇铜镍矿床的岩相学、锆石U-Pb年代学、地球化学特征:对东疆镁铁-超镁铁质岩体源区和成因的制约[J].岩石学报,2009,25(4):817-831.TANG Dongmei,QIN Kezhang,SUN He,et al.Lithological,chronological and geochemical charactristics of Tianyu Cu-Ni deposit:Constrain on source and genesis of mafic-ultramafic intrusions in eastern Xinjiang[J].Acta Petrologica Sinica,2009,25(4):817-831.
[24]刘丛强,李和平,黄智龙,等.地幔氧逸度的研究进展[J].地学前缘,2001,8(3):73-82.LIU Congqiang,LI Heping,HUANG Zhilong,et al.A reciew of studies on oxygen fugacity of earth mantle[J].Earth Science Frontiers,2001,8(3):73-82.
[25]Haughton D R,Roeder P L,Skinner B J.Solubility of sulphur in mafic magmas[J].Econ Geol,1974,69:451-467.
[26]Sharpe M R.The chronology of magma influxes to the eastern compartment,Bushveld Complex,as exemplified by its marginal border groups[J].Journal of Geological Society London,1981,81:373-378.
[27]Grinenko L N.Sources of sulfur of the nickeliferous and barren gabbro-dolerite intrusions of the northwest Siberian platform[J].Int.Geo l.Rev,1985,27:695-708.
[28]von Scherbler W H T M,Cawthorn R G,Kenyon A K,et al.Nickel-Cu sulphide mineralization In the Uitkomst Intrusion[C]//Extended Abstracts of the Cetennial Geocongress(1995).Geological Society of South Africa,Johannesburg,South Africa,1995:133-l36.
[29]Gauert C D K.The petrogenesis of the uitkomst complex,mpumalanga province,south africa[D].University of Pretoria,South Africa,1998:1-315.
[30]Laurence R.Introduction to ore-forming processes[M].England:Blackwell Publishing,2005:37-57.
[31]Naslund H R.Liquid immiscibility in the system KAlSi3O8-NaAlSi3O8-FeO-Fe2O3-SiO2and its application to natural magmas[J].Year Book,Carnegie Institution of Washington,1976,75:592-597.
[32]何国琦,李茂松,刘德权,等.中国新疆古生代地壳演化与成矿[M].乌鲁木齐:新疆人民出版社,香港:香港文化教育出版社,1994:241-245.HE Guoqi,LI Maosong,LIU Dequan,et al.Paleozoic crustal evolution and mineralization in Xinjiang of China[M].Urumchi:Xinjiang people,s publishing house,Hongkong:Educational and cultural press Ltd.,1994:241-245.
[33]陈哲夫,成守德,梁云海,等.新疆开合构造与成矿[M].乌鲁木齐:新疆科技卫生出版社,1997:394.CHEN Zhefu,CHENG Shoude,LIANG Yunhai,et al.Opening-closing tectonics and metallogenesis in Xinjiang[M].Urumchi:Xinjiang Sci-Tech and Public Health Press,1997:394.
[2]宋谢炎,马润泽,张正阶,等.攀枝花层状侵入体微型韵律层理及岩浆演化特征[J].矿物岩石,1994,14(4):37-45.SONG Xieyan,MA Runze,ZHANG Zhengjie,et al.The characteristics of layering and magma evolution of Panzhihua layered intrusion[J].Journal of Mineralogy and Petrology,1994,14(4):37-45.
[3]胡素芳,钟宏,刘秉光,等.攀西地区红格层状岩体的地球化学特征[J].地球化学,2001,30(2):131-138.HU Sufang,ZHONG Hong,LIU Bingguang,et al.Geochemistry of the Hongge layered intrusion in the Panxi area[J].Geochemistry,2001,30(2):131-138.
[4]Zhou M F,Christina W Y,Pang K N,et al.Origin of giant Fe-Ti-V oxide deposits in layered gabbroic intrusions,Panxi district,Sichuan Province,SW China[M].In:Jingwen Mao and Frank P.Bierlein(eds.),Mineral Deposit Research:Meeting the Global Challenge.Springer Berlin Heidelberg,2005,511-513.
[5]惠卫东.东天山尾亚钒钛磁铁矿地质特征和成因探讨[J].新疆有色金属,2009,6:1-4.HUI Weidong.The characteristics and genesis of vanadium-bearing titanomagnetite in Weiya deposit,east Tianshan[J].Xinjiang youse jinshu,2009,6:1-4.
[6]王玉往,王京彬,王莉娟,等.新疆尾亚含矿岩体锆石U-Pb年龄、Sr-Nd同位素组成及其地质意义[J].岩石学报,2008,24(4):781-792.WANG Yuwang,WANG Jingbin,WANG Lijuan,et al.Zircon U-Pb age,Sr-Nd isotope geochemistry and geological significances of the Weiya mafic-ultramafic complex,Xinjiang[J].Acta petrologica sinica,2008,24(4):781-792.
[7]王京彬,王玉往.新疆尾亚钒钛磁铁矿矿床成矿年龄探讨[J].矿床地质,2006,24(s):309-312.WANG Jingbin,WANG Yuwang.Metallogenetic chronology of the Weiya vanadium-bearing titanomagnetite deposit in Xinjiang[J].Mineral deposits,2006,24(s):309-312.
[8]李玫,王玉往,王京彬,等.新疆尾亚地区岩浆混合作用的年代学证据[J].中国地质,2010,37(1):39-47.LI Mei,WANG Yuwang,WANG Jingbin,et al.Zircon U-Pb chronologic evidence for magma mixing in the Weiya ore district,Xinjiang[J].Geology in China,2010,37(1):39-47.
[9]李锦轶,王克卓,李文铅,等.东天山晚古生代以来大地构造与矿产勘查[J].新疆地质,2002,20(4):295-301.LI Jinyi,WANG Kezhang,LI Wenqian,et al.Tectonic evolution since the late paleozoic and mineral preospecting in eastern Tianshan,NW China[J].Xinjiang Geology,2002,20(4):295-301.
[10]王玉往,王京彬,王莉娟,等.新疆尾亚钒钛磁铁矿——个岩浆分异-贯入-热液型复成因矿床[J].矿床地质,2005,24(4):349-360.WANG Yuwang,WANG Jingbin,WANG Lijuan,et al.Weiya vanadium-bearing titanomagnetite deposit in Xinjiang:A polygenetic magmatic differentiation-magmatic injection-magmatic hydrothermal deposit[J].Mineral Deposits,2005,24(4):349-360.
[11]Zhang Z Z,Gu L X,Wu C Z,et a1.Zircon SHRIMP dating for the Weiya pluton,eastern Tianshan:Its geological impfications[J].Acta Geologica Sinica:English Edidon,2005,79(4):481-490.
[12]Wood D A,Joron J L,Treuil M.A reappraisal of the use of trace elements to classify and discriminate between magma series erupted in different tectonic settings[J].Earth Planet Sci Let,1979,45:326-336.
[13]Saunders A D,Norry M J,Tarney J.Origin of MORB and chemically-depleted mantle reservoirs:trace element constraints[J].Journal of Petrology,Special Volume,1988:415-445.
[14]Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society,London,Special Publication,1989,42:313-345.
[15]董云鹏,周鼎武,张国伟.东秦岭富水基性杂岩体地球化学特征及其形成环境[J].地球化学,1997,16(3):79-87.DONG Yunpeng,ZHOU Dingwu,ZHANG Guowei.Geochemistry and formation setting of Fushui complex,eastern Qinling[J].Geochemistry,1997,16(3):79-87.
[16]Sun S S,Nesbitt R W.Petrogenesis of Archaean ultrabasic and basic volcanic:Evidence from the rare earth elements[J].Contrib.Mineral.Petro.,1978,165:301-325.
[17]Weaver B L,Tarney J.Thermal aspects of komatiite generation and greenstone belt models[J].Nature,1979,279:689-692.
[18]Kyser T K,CarmeronW E,Nisbet E G.Boninite petrogenesis and alteration history:Constraints from stable isotope compositions of boninites from Caoe Vogel,New Caledonia and Cyprus[J].Contri Mineral Petrol,1986,93:222-226.
[19]Harmon R S,Kempton P D,Stosch H G,et al.18O/16O ratios in anhydrous spinel lherzolite xenoliths from the Sdhavaryn-Tsaram vo lcano,Mongolia[J].Earth Planet Sci Lett,1987,81:193-202.
[20]Mattey D,Lowry D,M cpherson C.Oxygen isotope composition of mantle periotite[J].Earth Planet Sci L ett.,1994,128:231-241.
[21]Neal C R,Mahoney J J,Chazey W J.Mantle sources and the highly variable role of continental lithosphere in basalt petrogenesis of the Kerguelen Plateau and Broken Ridge LIP:results from ODP Leg 183[J].J Petrol,2002,43:1177-1205.
[22]Chai F M,Zhang Z C,Mao J W,et al.Geology,petrology and geochemistry of the Baishiquan Ni-Cu-bearing mafic-ultramaficintrusions in Xin jiang,NW China:Implications for tectonics and genesis of ores[J].Journal of Asian Earth Sciences,2008,32:218-235.
[23]唐冬梅,秦克章,孙赫,等.天宇铜镍矿床的岩相学、锆石U-Pb年代学、地球化学特征:对东疆镁铁-超镁铁质岩体源区和成因的制约[J].岩石学报,2009,25(4):817-831.TANG Dongmei,QIN Kezhang,SUN He,et al.Lithological,chronological and geochemical charactristics of Tianyu Cu-Ni deposit:Constrain on source and genesis of mafic-ultramafic intrusions in eastern Xinjiang[J].Acta Petrologica Sinica,2009,25(4):817-831.
[24]刘丛强,李和平,黄智龙,等.地幔氧逸度的研究进展[J].地学前缘,2001,8(3):73-82.LIU Congqiang,LI Heping,HUANG Zhilong,et al.A reciew of studies on oxygen fugacity of earth mantle[J].Earth Science Frontiers,2001,8(3):73-82.
[25]Haughton D R,Roeder P L,Skinner B J.Solubility of sulphur in mafic magmas[J].Econ Geol,1974,69:451-467.
[26]Sharpe M R.The chronology of magma influxes to the eastern compartment,Bushveld Complex,as exemplified by its marginal border groups[J].Journal of Geological Society London,1981,81:373-378.
[27]Grinenko L N.Sources of sulfur of the nickeliferous and barren gabbro-dolerite intrusions of the northwest Siberian platform[J].Int.Geo l.Rev,1985,27:695-708.
[28]von Scherbler W H T M,Cawthorn R G,Kenyon A K,et al.Nickel-Cu sulphide mineralization In the Uitkomst Intrusion[C]//Extended Abstracts of the Cetennial Geocongress(1995).Geological Society of South Africa,Johannesburg,South Africa,1995:133-l36.
[29]Gauert C D K.The petrogenesis of the uitkomst complex,mpumalanga province,south africa[D].University of Pretoria,South Africa,1998:1-315.
[30]Laurence R.Introduction to ore-forming processes[M].England:Blackwell Publishing,2005:37-57.
[31]Naslund H R.Liquid immiscibility in the system KAlSi3O8-NaAlSi3O8-FeO-Fe2O3-SiO2and its application to natural magmas[J].Year Book,Carnegie Institution of Washington,1976,75:592-597.
[32]何国琦,李茂松,刘德权,等.中国新疆古生代地壳演化与成矿[M].乌鲁木齐:新疆人民出版社,香港:香港文化教育出版社,1994:241-245.HE Guoqi,LI Maosong,LIU Dequan,et al.Paleozoic crustal evolution and mineralization in Xinjiang of China[M].Urumchi:Xinjiang people,s publishing house,Hongkong:Educational and cultural press Ltd.,1994:241-245.
[33]陈哲夫,成守德,梁云海,等.新疆开合构造与成矿[M].乌鲁木齐:新疆科技卫生出版社,1997:394.CHEN Zhefu,CHENG Shoude,LIANG Yunhai,et al.Opening-closing tectonics and metallogenesis in Xinjiang[M].Urumchi:Xinjiang Sci-Tech and Public Health Press,1997:394.