帕米尔东缘杜格里富碱斑岩锆石U-Pb定年、地球化学特征及构造意义
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摘要
帕米尔构造结是陆陆碰撞造山的典型地区之一,位于帕米尔东缘的杜格里富碱斑岩是揭示帕米尔新生代构造演化的重要对象。岩体侵位于下二叠统粉砂质板岩中,主要由正长斑岩和石英正长斑岩组成。通过锆石LA-ICP-MS U-Pb定年获得岩体的成岩年龄为10.76±0.09 Ma,表明杜格里富碱斑岩形成于中新世中期。地球化学分析结果显示,杜格里岩体具富碱、高钾、准铝质—弱过铝质的特征,微量元素高度富集Rb、Sr、Ba等大离子亲石元素(LILE),而亏损Nb、Ta、Ti等高场强元素(HFSE),稀土元素总量较高,球粒陨石标准化配分型式呈右陡倾的LREE富集型,且无明显负Eu异常,反应源区为加厚镁铁质下地壳,并经历过古俯冲洋壳板片流体的交代作用和富集地幔物质的加入。综合分析认为,杜格里富碱斑岩形成于后碰撞阶段伸展构造体制下,是青藏高原西北缘构造转换带对印度-欧亚大陆碰撞造山过程响应的记录。
The Pamir syntaxis is one of the typical continental collision orogeny.The Dugeli alkali-rich porphyries on the eastern margin of Pamir is of great significance to reveal the Cenozoic tectonic evolution in this area.The rock mass intrudes into silty slate of the Early Permian and is mainly composed of syenite porphyry and quartz syenite porphyry.The LA-ICP-MS zircon U-Pb dating of the Dugeli porphyry yielded an age of 10.76±0.09 Ma,revealing that the rocks formed in the Middle Miocene.Geochemical analysis indicates that the Dugeli porphyry belongs to the metaluminous to weakly peraluminous A-type granite with features of alkali-rich,high-potassium.Trace elements show high enrichment of LILE,such as Rb,Sr,and Ba,and depletion of HFSE,such as Nb,Ta and Ti.The total REE content in the porphyry is high,and the REE chondrite-normalized distribution pattern shows distinct right leaning,light REE enrichment,with no obvious negative Eu anomaly.These features suggest that the magma source is the thickened mafic lower crust,which underwent metasomatism of ancient subducted oceanic slab fluids and was injected by enrichment mantle material.It is concluded that the Dugeli alkali-rich porphyry was formed in extensional tectonic setting during the post-collision stage and records the response to the IndiaEurasia collision orogeny in the tectonic transition zone of northwest of the Qinghai-Tibet Plateau.
The Pamir syntaxis is one of the typical continental collision orogeny.The Dugeli alkali-rich porphyries on the eastern margin of Pamir is of great significance to reveal the Cenozoic tectonic evolution in this area.The rock mass intrudes into silty slate of the Early Permian and is mainly composed of syenite porphyry and quartz syenite porphyry.The LA-ICP-MS zircon U-Pb dating of the Dugeli porphyry yielded an age of 10.76±0.09 Ma,revealing that the rocks formed in the Middle Miocene.Geochemical analysis indicates that the Dugeli porphyry belongs to the metaluminous to weakly peraluminous A-type granite with features of alkali-rich,high-potassium.Trace elements show high enrichment of LILE,such as Rb,Sr,and Ba,and depletion of HFSE,such as Nb,Ta and Ti.The total REE content in the porphyry is high,and the REE chondrite-normalized distribution pattern shows distinct right leaning,light REE enrichment,with no obvious negative Eu anomaly.These features suggest that the magma source is the thickened mafic lower crust,which underwent metasomatism of ancient subducted oceanic slab fluids and was injected by enrichment mantle material.It is concluded that the Dugeli alkali-rich porphyry was formed in extensional tectonic setting during the post-collision stage and records the response to the IndiaEurasia collision orogeny in the tectonic transition zone of northwest of the Qinghai-Tibet Plateau.
引文
陈杰,李涛,李文巧.2011.帕米尔构造结及临区的晚新生代构造与现今变形.地震地质,33(2):241~259.
丁林,张进江,周勇,邓万明,许荣华,钟大赉.1999.青藏高原岩石圈演化的记录:藏北超钾质及钠质火山岩的岩石学与地球化学特征.岩石学报,15(3):408~421.
洪俊,计文化,张辉善,姚文光,孟广路,王斌,吕鹏瑞,杨博.2014.南帕米尔北缘切实界别辉长岩LA-ICP-MS锆石U-Pb定年、地球化学特征及其地质意义.地质通报,33(6):820~829.
侯增谦,钟大赉,邓万明.2004.青藏高原东缘斑岩铜钼金成矿带的构造模式.中国地质,31(1):1~14.
姜春发,杨经绥,冯秉贵,赵民,柴耀楚.1992.昆仑开合构造.北京:地质出版社,1~224.
柯珊,罗照华,莫宣学,张文会,梁涛,詹华明.2008.帕米尔构造结塔什库尔干碱性杂岩同位素年代学研究.岩石学报,24(2):315~324.
李海兵,valli F,许志琴,杨经绥,Tapponnier P,Lacassin R,陈松永.2006.喀喇昆仑断裂的变形特征及构造演化.中国地质,33(2):239~254.
李海兵,Valli F,Arnaud N,陈松永,徐志琴.2008.喀喇昆仑断裂带走滑过程中伴随的快速隆升作用:热年代学证据.岩石学报,24(7):1552~1566.
林清茶,夏斌,张玉泉.2006.西昆仑-喀喇昆仑地区钾质碱性岩ArAr年龄:以羊湖、昝坎和苦子干岩体为例.矿物岩石,26(2):66~70.
罗照华,莫宣学,柯珊.2003.塔什库尔干碱性杂岩体形成时代及其地质意义.新疆地质,21(1):46~50.
马昌前,明厚利,杨坤光.2004.大别山北麓的奥陶纪岩浆弧:侵入岩年代学和地球化学证据.岩石学报,20(3):393~402.
涂光炽,张玉良,赵振华.1984.华南两个富碱侵入岩带的初步研究.见:徐克勤,涂光炽,主编.花岗岩地质和成矿关系.南京:江苏科学技术出版社,20~37.
潘裕生.2000.喀喇昆仑山-昆仑山地区地质演化.北京:科学出版社,1~258.
闫义,林柯,李自安.2003.利用锆石形态、成分组成及年龄分析进行沉积物源区示踪的综合研究.大地构造与成矿学,27(2):184~190.
吴元保,郑永飞.2004.锆石成因矿物学研究及其对U-Pb年龄解释的制约.科学通报,49(16):1589~1604.
张旗,王焰,钱青.2001.中国东部燕山期埃达克岩的特征及其构造意义.岩石学报,17(2):236~244.
Ballard J R,Palin J M,Williams I S,et al.2001.Two ages of\sporphyry intrusion resolved for the super-giant Chuquicamata\scopper deposit of northern Chile by LA-ICP-MS and SHRIMP.Geology,9:383~386.
Bonin B.1990.From orogenic to anorogenic settings:evolution of\sgranitoid suites after a major orogenesis.Geological Journal,25:261~270.
Burtman V S,Molnar P.1993.Geological and geophysical evidence\sfor deep subduction of continental crust beneath the Pamir.The\sgeological society of America,Special paper,281:1~76.
Ducea M N,Lutkov V,Minaev V T,Hacker B,Luffi P,Metcalf J.2003.Building the Pamirs:the view from the underside.Geological Society of America,31(10):849~852.
Hacker B,Luffi P,Lutkov V,Minaev V.2005.Near-Ultrahigh\sPressure Processing of Continental Crust:Miocene Crustal\sXenoliths from the Pamir.Journal of Petrology,46(8):1661~1687.
Horn I,Rudnick R L,Mcdonough W F.2000.Precise element and\sisotope ratio derermination by simultaneous solution\snebulization and LA-ICP-MS:Application to U-Pb\sgeochronology.Chemical Geology,167:405~425.
Ionov D A,Hofmann A W.1995.Nb-Ta-rich mantle amphiboles\sand micas:Implications for subduction-related metasomatic\strace-element fractionations.Earth and Planetary Science\sLetters,131(3~4):341~356.
Kosler J,Fonneland H,Sylvester P.2002.U-Pb dating of detrital\szircons for sediment provenance studies-acomparison of LA-ICP-MS and SIMS techniques.Chemical Geology,182:605~618.
Lacassin R,Valli F,Arnaud N,Lcloup A P,Paqucttc J L,Li\sHaibing,Tapponnier P.2004.Large-scale geometry,offset\sand kinematic evolution of the Karakorum fault,Tibet.Earth\sand Planetary Science Letters,219:255~269.
Ludwing K R.2003.Isoplot 3.0-A geochronological toolkit for\sMicrosoft Excel.Berkeley Geochronological Center,Special\sPublication,(4):1~70.
Muller D,Groves D I.2000.Potassic igneous rocks and associated\sgold-copper mineralization.3rd,updated and enlarged edition,Springer,1~209.
Pearce J A.1984.Trace element discrimination diagram for tectonic\sinterpretation of granitic rocks.Petrology,25:656~682.
Rudnick R L,Fountain D M.1995.Nature and composition of the\scontinental crust:A lower crustal perspective.Review\sGeophysics,33:267~309.
Stern S,Kilian R.1996.Role of the subducted slab,mantle wedge\sand continental crust in the revelation of adakites from the\sAndean Austral volcanic zone.Contributions to Mineralogy and\sPetrology,123(3):263~281.
Sun S S,McDonough W F.1989.Chemical and isotopic systematic\sof oceanic basalts:implications for mantle composition and\sprocesses.In:Saunders A D,Norry M J,eds.Magmatsm in\sthe Ocean Basins.Geological Society Special Publication,42:313~345.
Vavra G,Gebauer D,Schmid R.1996.Multiple zircon growth and\srecrystallization during polyphase Late Carboniferous to Triassic\smetamorphism in granulites of Ivrea Zone:anion microprobe\sstudy.Contributions to Mineralogy and Petrology,122:337~358.
Vavra G,Schmid R,Gebauer D.1999.Internal morphology,habit\sand U-Th-Pb microanalysis of amphibolite-to-granulite facies\szircons:geochronology of the Ivrea zone(southern Alps).Contrib Mineral Petrol,134:380~404.
Vrublevskii V V,Krupchatnikov V I,Izokh A E,et al.2012.The\salkaline and carbonatitic rocks of Gorny Altai(Edel'veis\scomplex)as indicators of Early Paleozoic plume magmatism in\sthe Central Asian Fold Belt.Russian Geology and Geophysics,53(8):721~735.
Wang Qiuliang,McDermott F P,Xu Jifeng,Bellon H,Zhu\sYingtang.2005.Cenozoic K-rich adakitic volcanic rocks in the\sHohxil area,northern Tibet:lower-crustal melting in an\sintracontinental setting.Geology,33:465~468.
Wang Tao,Liu Shen,Hu Ruizhong,Feng Caixia,Qi Youqiang,Feng Guangying,Yang Yuhong.2010.Petrogenesis of alkaline\srocks in the Sulu Orogen-evidence from elemental\sgeochemistry.Acta Mineralogica Sinica,30(2):194~205.
Woolley A R.2001.Alkaline Rocks and Carbonatites of the World.The Geological Society London,1~212.
Yuan Honglin,Gao Shan,Liu Xiaoming,Li Huiming,Gunther D,Wu Fuyuan.2004.Accurate U-Pb age and trace element\sdeterminations of zircon by laser ablation-inductively coupled\splasma mass spectrometry.Geostandards and Geoanalytical\sResearch,28(3):353~370.
苏联国家地质委员会.1956.苏联1∶20万区域地质图,图幅号J43-XXI.
丁林,张进江,周勇,邓万明,许荣华,钟大赉.1999.青藏高原岩石圈演化的记录:藏北超钾质及钠质火山岩的岩石学与地球化学特征.岩石学报,15(3):408~421.
洪俊,计文化,张辉善,姚文光,孟广路,王斌,吕鹏瑞,杨博.2014.南帕米尔北缘切实界别辉长岩LA-ICP-MS锆石U-Pb定年、地球化学特征及其地质意义.地质通报,33(6):820~829.
侯增谦,钟大赉,邓万明.2004.青藏高原东缘斑岩铜钼金成矿带的构造模式.中国地质,31(1):1~14.
姜春发,杨经绥,冯秉贵,赵民,柴耀楚.1992.昆仑开合构造.北京:地质出版社,1~224.
柯珊,罗照华,莫宣学,张文会,梁涛,詹华明.2008.帕米尔构造结塔什库尔干碱性杂岩同位素年代学研究.岩石学报,24(2):315~324.
李海兵,valli F,许志琴,杨经绥,Tapponnier P,Lacassin R,陈松永.2006.喀喇昆仑断裂的变形特征及构造演化.中国地质,33(2):239~254.
李海兵,Valli F,Arnaud N,陈松永,徐志琴.2008.喀喇昆仑断裂带走滑过程中伴随的快速隆升作用:热年代学证据.岩石学报,24(7):1552~1566.
林清茶,夏斌,张玉泉.2006.西昆仑-喀喇昆仑地区钾质碱性岩ArAr年龄:以羊湖、昝坎和苦子干岩体为例.矿物岩石,26(2):66~70.
罗照华,莫宣学,柯珊.2003.塔什库尔干碱性杂岩体形成时代及其地质意义.新疆地质,21(1):46~50.
马昌前,明厚利,杨坤光.2004.大别山北麓的奥陶纪岩浆弧:侵入岩年代学和地球化学证据.岩石学报,20(3):393~402.
涂光炽,张玉良,赵振华.1984.华南两个富碱侵入岩带的初步研究.见:徐克勤,涂光炽,主编.花岗岩地质和成矿关系.南京:江苏科学技术出版社,20~37.
潘裕生.2000.喀喇昆仑山-昆仑山地区地质演化.北京:科学出版社,1~258.
闫义,林柯,李自安.2003.利用锆石形态、成分组成及年龄分析进行沉积物源区示踪的综合研究.大地构造与成矿学,27(2):184~190.
吴元保,郑永飞.2004.锆石成因矿物学研究及其对U-Pb年龄解释的制约.科学通报,49(16):1589~1604.
张旗,王焰,钱青.2001.中国东部燕山期埃达克岩的特征及其构造意义.岩石学报,17(2):236~244.
Ballard J R,Palin J M,Williams I S,et al.2001.Two ages of\sporphyry intrusion resolved for the super-giant Chuquicamata\scopper deposit of northern Chile by LA-ICP-MS and SHRIMP.Geology,9:383~386.
Bonin B.1990.From orogenic to anorogenic settings:evolution of\sgranitoid suites after a major orogenesis.Geological Journal,25:261~270.
Burtman V S,Molnar P.1993.Geological and geophysical evidence\sfor deep subduction of continental crust beneath the Pamir.The\sgeological society of America,Special paper,281:1~76.
Ducea M N,Lutkov V,Minaev V T,Hacker B,Luffi P,Metcalf J.2003.Building the Pamirs:the view from the underside.Geological Society of America,31(10):849~852.
Hacker B,Luffi P,Lutkov V,Minaev V.2005.Near-Ultrahigh\sPressure Processing of Continental Crust:Miocene Crustal\sXenoliths from the Pamir.Journal of Petrology,46(8):1661~1687.
Horn I,Rudnick R L,Mcdonough W F.2000.Precise element and\sisotope ratio derermination by simultaneous solution\snebulization and LA-ICP-MS:Application to U-Pb\sgeochronology.Chemical Geology,167:405~425.
Ionov D A,Hofmann A W.1995.Nb-Ta-rich mantle amphiboles\sand micas:Implications for subduction-related metasomatic\strace-element fractionations.Earth and Planetary Science\sLetters,131(3~4):341~356.
Kosler J,Fonneland H,Sylvester P.2002.U-Pb dating of detrital\szircons for sediment provenance studies-acomparison of LA-ICP-MS and SIMS techniques.Chemical Geology,182:605~618.
Lacassin R,Valli F,Arnaud N,Lcloup A P,Paqucttc J L,Li\sHaibing,Tapponnier P.2004.Large-scale geometry,offset\sand kinematic evolution of the Karakorum fault,Tibet.Earth\sand Planetary Science Letters,219:255~269.
Ludwing K R.2003.Isoplot 3.0-A geochronological toolkit for\sMicrosoft Excel.Berkeley Geochronological Center,Special\sPublication,(4):1~70.
Muller D,Groves D I.2000.Potassic igneous rocks and associated\sgold-copper mineralization.3rd,updated and enlarged edition,Springer,1~209.
Pearce J A.1984.Trace element discrimination diagram for tectonic\sinterpretation of granitic rocks.Petrology,25:656~682.
Rudnick R L,Fountain D M.1995.Nature and composition of the\scontinental crust:A lower crustal perspective.Review\sGeophysics,33:267~309.
Stern S,Kilian R.1996.Role of the subducted slab,mantle wedge\sand continental crust in the revelation of adakites from the\sAndean Austral volcanic zone.Contributions to Mineralogy and\sPetrology,123(3):263~281.
Sun S S,McDonough W F.1989.Chemical and isotopic systematic\sof oceanic basalts:implications for mantle composition and\sprocesses.In:Saunders A D,Norry M J,eds.Magmatsm in\sthe Ocean Basins.Geological Society Special Publication,42:313~345.
Vavra G,Gebauer D,Schmid R.1996.Multiple zircon growth and\srecrystallization during polyphase Late Carboniferous to Triassic\smetamorphism in granulites of Ivrea Zone:anion microprobe\sstudy.Contributions to Mineralogy and Petrology,122:337~358.
Vavra G,Schmid R,Gebauer D.1999.Internal morphology,habit\sand U-Th-Pb microanalysis of amphibolite-to-granulite facies\szircons:geochronology of the Ivrea zone(southern Alps).Contrib Mineral Petrol,134:380~404.
Vrublevskii V V,Krupchatnikov V I,Izokh A E,et al.2012.The\salkaline and carbonatitic rocks of Gorny Altai(Edel'veis\scomplex)as indicators of Early Paleozoic plume magmatism in\sthe Central Asian Fold Belt.Russian Geology and Geophysics,53(8):721~735.
Wang Qiuliang,McDermott F P,Xu Jifeng,Bellon H,Zhu\sYingtang.2005.Cenozoic K-rich adakitic volcanic rocks in the\sHohxil area,northern Tibet:lower-crustal melting in an\sintracontinental setting.Geology,33:465~468.
Wang Tao,Liu Shen,Hu Ruizhong,Feng Caixia,Qi Youqiang,Feng Guangying,Yang Yuhong.2010.Petrogenesis of alkaline\srocks in the Sulu Orogen-evidence from elemental\sgeochemistry.Acta Mineralogica Sinica,30(2):194~205.
Woolley A R.2001.Alkaline Rocks and Carbonatites of the World.The Geological Society London,1~212.
Yuan Honglin,Gao Shan,Liu Xiaoming,Li Huiming,Gunther D,Wu Fuyuan.2004.Accurate U-Pb age and trace element\sdeterminations of zircon by laser ablation-inductively coupled\splasma mass spectrometry.Geostandards and Geoanalytical\sResearch,28(3):353~370.
苏联国家地质委员会.1956.苏联1∶20万区域地质图,图幅号J43-XXI.