西藏日土白垩纪酸性侵入岩年代学及地球化学特征——对班公湖-怒江中特提斯洋盆闭合时限的制约
|
摘要
以西藏日土县北东地区的小型酸性侵入体为研究对象,结合岩石地球化学分析及锆石年龄测试,探讨岩石的成因类型及构造环境,确定班公湖-怒江中特提斯洋盆闭合的时限。研究区酸性岩体的岩性为黑云二长花岗岩,其主要组分的质量分数分别是:SiO_2为63.89%~77.49%,全碱(K_2O+Na_2O)为8.06%~8.95%,全铁(FeOT)为0.48%~4.37%,Al_2O_3为12.43%~16.17%;大离子亲石元素中Rb、Th、U、K明显富集,但Ba、Sr明显亏损;高场强元素中Nb、Ta、P、Ti明显亏损,而Zr、Hf相对富集;轻稀土元素相对富集、重稀土元素相对亏损,负Eu异常明显(δEu=0.09~0.67,平均为0.47),球粒原始标准化分布模式为向右缓倾的V型,属于A型花岗岩。其LA-ICP-MS锆石206Pb/238 U年龄加权平均值为(117.8±1.2)Ma,属于中生代早白垩世中期。从岩石碰撞后A1型花岗岩特征推测,班公湖-怒江中特提斯洋盆在日土地区的闭合时间应在早白垩世中期。
The petrogenesis and structural environment of small intrusive acid rock masses in the northeast Ritu County of Tibet are studied so as to investigate the closure time of the Bangong LakeNujiang Middle Tethys oceanic basin.Lithological and geochemical studies show that the rock type of the acid rocks in this area is biotite monzonitic granite.These rocks consist mainly of SiO_2,(K_2O +Na_2O),(FeOT)and Al_2O_3 with the mass fractions of 63.89%~77.49%,8.06%~8.95%,0.48%~4.37%,12.43%~16.17%.Large ion lithophile elements(LILE)Rb,Th,U,K obviously enriched but Ba,Sr obvious depleted;high field strength elements(HFSE)Nb,Ta,P,Ti obvious depleted and Zr, Hf relative enriched;LREE relatively enriched, HREE relative loss;high degree of fractionation and negative Eu anomalies(δEu=0.09~0.67,an average of 0.47),with primitive chondrite normalized distribution pattern of being gently right sloping V-type.Above all,the acid rock belongs to A1-type granite.LA-ICP-MS dating shows that the zircon 206Pb/238 U weighted mean age of biotite monzonitic granite is(117.8±1.2)Ma,the early Cretaceous period in Mesozoic.From the zircon U-Pb ages and post-collisional A-type features,the Bangong Lake-Nujiang Middle Tethys oceanic basin in Ritu County area is considered to be closed in the middle phase of early Cretaceous.
The petrogenesis and structural environment of small intrusive acid rock masses in the northeast Ritu County of Tibet are studied so as to investigate the closure time of the Bangong LakeNujiang Middle Tethys oceanic basin.Lithological and geochemical studies show that the rock type of the acid rocks in this area is biotite monzonitic granite.These rocks consist mainly of SiO_2,(K_2O +Na_2O),(FeOT)and Al_2O_3 with the mass fractions of 63.89%~77.49%,8.06%~8.95%,0.48%~4.37%,12.43%~16.17%.Large ion lithophile elements(LILE)Rb,Th,U,K obviously enriched but Ba,Sr obvious depleted;high field strength elements(HFSE)Nb,Ta,P,Ti obvious depleted and Zr, Hf relative enriched;LREE relatively enriched, HREE relative loss;high degree of fractionation and negative Eu anomalies(δEu=0.09~0.67,an average of 0.47),with primitive chondrite normalized distribution pattern of being gently right sloping V-type.Above all,the acid rock belongs to A1-type granite.LA-ICP-MS dating shows that the zircon 206Pb/238 U weighted mean age of biotite monzonitic granite is(117.8±1.2)Ma,the early Cretaceous period in Mesozoic.From the zircon U-Pb ages and post-collisional A-type features,the Bangong Lake-Nujiang Middle Tethys oceanic basin in Ritu County area is considered to be closed in the middle phase of early Cretaceous.
引文
[1]Pearce J A,Deng W M.The ophiolites of the Tibet geotraverses,Lhasa to Golmud(1985)and Lhasa to Kathmandu(1986)[J].Phil Tran Roy Soc Lond Math Phys Sci,1988,327(1954):215-238.doi:10.1098/rsta.1988.0127.
[2]Kapp P,Murphy M A,Yin A,et al.Mesozoic and Cenozoic evolution of the Shiquanhe area of western Tibet[J].Tectonics,2003,22(4):1029.
[3]李光明,李金祥,秦克章,等.西藏班公湖-带多不杂超大型富金斑岩铜矿的高温高盐高氧化成矿流体---流体包裹体证据[J].岩石学报,2007,23(5):935-952.Li G M,Li J X,Qin K Z,et al.High temperature,salinity and strong oxidation ore-forming fluid at Duobuza gold-rich porphyry copper deposit in the Bangonghu tectonic belt,Tibet:Evidence from fluid inclusions[J].Acta Ptrologica Sinica,2007,23(5):935-952.(in Chinese)
[4]许荣科,郑有业,赵平甲,等.西藏东巧北尕苍见岛弧的厘定及地质意义[J].中国地质,2007,34(5):768-777.Xu R K,Zheng Y Y,Zhao P J,et al.Definition and geological significance of Gacangjian volcanic arc north of Dongqiao,Tibet[J].Geol China,2007,34(5):768-777.(in Chinese)
[5]李金祥,李光明,秦克章,等.班公湖多不杂富金斑岩铜矿床斑岩-火山岩的地球化学特征与时代:对成矿构造背景的制约[J].岩石学报,2008,24(3):531-543.Li J X,Li G M,Qin K Z,et al.Geochemistry of porphyries and volcanic rocks and ore-forming geochronology of Duobuza gold-rich porphyry copper deposit in Bangonghu belt,Tibet:Constraints on metallogenic tectonic setting[J].Acta Petrologica Sinica,2008,24(3):531-543.(in Chinese)
[6]曲晓明,王瑞江,辛洪波,等.西藏西部与班公湖特提斯洋盆俯冲相关的火成岩年代学和地球化学[J].地球化学,2009,38(6):523-535.Qu X M,Wang R J,Xin H B,et al.Geochronology and geochemistry of igneous rocks related to the subduction of the Tethys oceanic plate along the Bangong Lake arc zone,the western Tibetan Plateau[J].Geochimica,2009,38(6):523-535.(in Chinese)
[7]康志强,许继峰,王保弟,等.拉萨地块北部去申拉组火山岩:班公湖-怒江特提斯洋南向俯冲的产物[J].岩石学报,2010,26(10):3106-3116.Kang Z Q,Xu J F,Wang B D,et al.Qushenla Formation volcanic rocks in north Lhasa block:Products of Bangong Co-Nujiang Tethys southward subduction[J].Acta Petrologica Sinica,2010,26(10):3106-3116.(in Chinese)
[8]杜德道,曲晓明,王根厚,等.西藏班公湖-怒江缝合带西段中特提斯洋盆的双向俯冲:来自岛弧型花岗岩锆石U-Pb年龄和元素地球化学的证据[J].岩石学报,2011,27(7):1993-2002.Du D D,Qu X M,Wang G H,et al.Bidirectional subduction of the middle Tethys oceanic basin in the west segment of Bangonghu-Nujiang suture,Tibet,evidence from zircon U-Pb LA-ICP-MS dating and petrogeochemistry of arc granities[J].Acta Petrologica Sinica,2011,27(7):1993-2002.(in Chinese)
[9]耿全如,潘桂棠,王立全,等.班公湖-怒江带、羌塘地块特提斯演化与成矿地质背景[J].地质通报,2011,30(8):1261-1274.Geng Q R,Pan G T,Wang L Q,et al.Tethyan evolution and metallogenic geological Background of the Bangong Co-Nujiang Belt and the Qiangtang Massif in Tibet[J].Geological Bulletin of China,2011,30(8):1261-1274.(in Chinese)
[10]Zhu D C,Zhao Z D,Niu Y L,et al.The Lhasa terrane:record of a microcontinent and its histories of drift and growth[J].Earth Planet Sci Lett,2011,301(1/2):241-255.
[11]Wang W L,Aitchision J C,Lo C H,et al.Geochemistry and geochronology of the amphibolite blocks in pphiolitic mélanges along Bangong-Nujiang suture,central Tibet[J].J Asian Earth Sci,2008,33(1/2):122-138.
[12]江军华,王瑞江,曲晓明,等.青藏高原西部班公湖岛弧带特提斯洋盆闭合后的地壳伸展作用[J].地球科学,2011,36(6):1021-1032.Jiang J H,Wang R J,Qu X M,et al.Crustal extension of the Bangong lake arc zone,western Tibetan plateau,after the closure of the Tethys oceanic basin[J].Earth Science,2011,36(6):1021-1032.(in Chinese)
[13]张向飞,李佑国,曹晓民,等.班公湖-怒江缝合带西段酸性侵入岩LA-ICP-MS锆石U-Pb年龄与地球化学特征[J].地质通报,2014,33(7):984-994.Zhang X F,Li Y G,Cao X M,et al.LA-ICP-MSzircon U-Pb age and geochemical characteristics of the acid intrusive rocks in the western part of Bangong Lake-Nujiang River suture zone[J].Geologocal Bulletin of China,2014,33(7):984-994.(in Chinese)
[14]侯可军,李延河,田有荣.LA-MC-ICP-MS锆石微区原位U-Pb定年技术[J].矿床地质,2009,28(4):481-492.Hou K J,Li Y H,Tian Y R.In situ U-Pb zircon dating using laser ablation-multi ion counting-ICP-MS[J].Mineral Deposit,2009,28(4):481-492.(in Chinese)
[15]Slama J,Kosler J,Condon D J,et al.Plesovice zircon-A new natural reference material for U-Pb and Hf isotopic microanalysis[J].Chemical Geology,2008,249:1-35.
[16]Loiselle M C,Wones D R.Characteristics and origin of anorogenic granites[J].Geological Society of America,1979,11(7):468.
[17]Chappell B W,White A J R.Two contrasting granite types[J].Pac Geol,1974,8:173-174.
[18]Eby G N.The A-type granitoids:A review of their occurrence and chemical characteristics and speculations on their petrogensis[J].Lithos,1990,26(1/2):115-134.
[19]Collins W J,Beams S D,White A J R,et al.Nature and origin of A-type granite with particular reference to southeast Australia[J].Contrib Mineral Petrol,1982,80(2):189-200.
[20]Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].J Petrol,1984,25(4):956-983.
[21]Batchelor R A,Bowden P.Petrogenetic interpretation of granitiod rock series using multicationic parameters[J].Chem Geol,1985,48(1/2/3/4):43-55.
[22]曲晓明,辛洪波,杜德道,等.西藏班公湖-怒江缝合带中段碰撞后A型花岗岩的时代及其对洋盆闭合时间的约束[J].地球化学,2012,41(1):1-14.Qu X M,Xin H B,Du D D,et al.Ages of postcollisional A-type granite and constraint on the closure of the oceanic basin in the middle segment of the Bangonghu-Nujiang suture,the Tibet plateau[J].Geochimica,2012,41(1):1-14.(in Chinese)
[23]Eby G N.Chemical subdivision of the A-type granitiods:Petrogenetic and tectonic implications[J].Geology,1992,20(7):641-644.
[24]Dargahi S,Arvin M,Pan Y M,et al.Petrogensis of post-collisional A-type granitiods from the Urumieh-Dokhtar magmatic assemblage,southwestern Kerman,Iran:Constraints on the ArabianEurasian continental collision[J].Lithos,2010,115(1/2/3/4):190-204.
[25]莫宣学,潘桂棠.从特提斯到青藏高原形成:构造-岩浆事件的约束[J].地学前缘,2006,13(6):43-51.Mo X X,Pan G T.From the Tethys to the formation of the Qinghai-Tibet Plateau:Constrained by tectono-magmatic events[J].Earth Science Frontiers,2006,13(6):43-51.(in Chinese)
[26]张玉修.班公湖-怒江缝合带中西段构造演化[D].广州:中国科学院广州地球化学研究所,2007:1-257.Zhang Y X.Tectonic Evolution of the MiddleWestern Bangong-Nujiang Suture,Tibet[D].Guangzhou:Guangzhou Institute of Geochemistry of the Chinese Academy of Science,2007:1-257.(in Chinese)
[27]赵元艺,崔玉斌,吕丽娜,等.西藏舍索矽卡岩型铜多金属矿床年代学与地球化学特征及意义[J].岩石学报,2011,27(7):2132-2142.Zhao Y Y,Cui Y B,Lyu L N,et al.Chronology,geochemical characteristic and the significance of Shesuo copper polymetallic deposit,Tibet[J].Acta Petrologica Sinica,2011,27(7):2132-2142.(in Chinese)
[28]陈国荣,刘鸿飞,蒋光武,等.西藏班公湖-怒江结合带中段沙木罗组的发现[J].地质通报,2004,23(2):193-194.Chen G R,Liu H F,Jiang G W,et al.Discovery of the Shamuluo Formation in the central segment of the Bangongcuo-Nujiang suture zone,Tibet[J].Geol Bull China,2004,23(2):193-194.(in Chinese)
[2]Kapp P,Murphy M A,Yin A,et al.Mesozoic and Cenozoic evolution of the Shiquanhe area of western Tibet[J].Tectonics,2003,22(4):1029.
[3]李光明,李金祥,秦克章,等.西藏班公湖-带多不杂超大型富金斑岩铜矿的高温高盐高氧化成矿流体---流体包裹体证据[J].岩石学报,2007,23(5):935-952.Li G M,Li J X,Qin K Z,et al.High temperature,salinity and strong oxidation ore-forming fluid at Duobuza gold-rich porphyry copper deposit in the Bangonghu tectonic belt,Tibet:Evidence from fluid inclusions[J].Acta Ptrologica Sinica,2007,23(5):935-952.(in Chinese)
[4]许荣科,郑有业,赵平甲,等.西藏东巧北尕苍见岛弧的厘定及地质意义[J].中国地质,2007,34(5):768-777.Xu R K,Zheng Y Y,Zhao P J,et al.Definition and geological significance of Gacangjian volcanic arc north of Dongqiao,Tibet[J].Geol China,2007,34(5):768-777.(in Chinese)
[5]李金祥,李光明,秦克章,等.班公湖多不杂富金斑岩铜矿床斑岩-火山岩的地球化学特征与时代:对成矿构造背景的制约[J].岩石学报,2008,24(3):531-543.Li J X,Li G M,Qin K Z,et al.Geochemistry of porphyries and volcanic rocks and ore-forming geochronology of Duobuza gold-rich porphyry copper deposit in Bangonghu belt,Tibet:Constraints on metallogenic tectonic setting[J].Acta Petrologica Sinica,2008,24(3):531-543.(in Chinese)
[6]曲晓明,王瑞江,辛洪波,等.西藏西部与班公湖特提斯洋盆俯冲相关的火成岩年代学和地球化学[J].地球化学,2009,38(6):523-535.Qu X M,Wang R J,Xin H B,et al.Geochronology and geochemistry of igneous rocks related to the subduction of the Tethys oceanic plate along the Bangong Lake arc zone,the western Tibetan Plateau[J].Geochimica,2009,38(6):523-535.(in Chinese)
[7]康志强,许继峰,王保弟,等.拉萨地块北部去申拉组火山岩:班公湖-怒江特提斯洋南向俯冲的产物[J].岩石学报,2010,26(10):3106-3116.Kang Z Q,Xu J F,Wang B D,et al.Qushenla Formation volcanic rocks in north Lhasa block:Products of Bangong Co-Nujiang Tethys southward subduction[J].Acta Petrologica Sinica,2010,26(10):3106-3116.(in Chinese)
[8]杜德道,曲晓明,王根厚,等.西藏班公湖-怒江缝合带西段中特提斯洋盆的双向俯冲:来自岛弧型花岗岩锆石U-Pb年龄和元素地球化学的证据[J].岩石学报,2011,27(7):1993-2002.Du D D,Qu X M,Wang G H,et al.Bidirectional subduction of the middle Tethys oceanic basin in the west segment of Bangonghu-Nujiang suture,Tibet,evidence from zircon U-Pb LA-ICP-MS dating and petrogeochemistry of arc granities[J].Acta Petrologica Sinica,2011,27(7):1993-2002.(in Chinese)
[9]耿全如,潘桂棠,王立全,等.班公湖-怒江带、羌塘地块特提斯演化与成矿地质背景[J].地质通报,2011,30(8):1261-1274.Geng Q R,Pan G T,Wang L Q,et al.Tethyan evolution and metallogenic geological Background of the Bangong Co-Nujiang Belt and the Qiangtang Massif in Tibet[J].Geological Bulletin of China,2011,30(8):1261-1274.(in Chinese)
[10]Zhu D C,Zhao Z D,Niu Y L,et al.The Lhasa terrane:record of a microcontinent and its histories of drift and growth[J].Earth Planet Sci Lett,2011,301(1/2):241-255.
[11]Wang W L,Aitchision J C,Lo C H,et al.Geochemistry and geochronology of the amphibolite blocks in pphiolitic mélanges along Bangong-Nujiang suture,central Tibet[J].J Asian Earth Sci,2008,33(1/2):122-138.
[12]江军华,王瑞江,曲晓明,等.青藏高原西部班公湖岛弧带特提斯洋盆闭合后的地壳伸展作用[J].地球科学,2011,36(6):1021-1032.Jiang J H,Wang R J,Qu X M,et al.Crustal extension of the Bangong lake arc zone,western Tibetan plateau,after the closure of the Tethys oceanic basin[J].Earth Science,2011,36(6):1021-1032.(in Chinese)
[13]张向飞,李佑国,曹晓民,等.班公湖-怒江缝合带西段酸性侵入岩LA-ICP-MS锆石U-Pb年龄与地球化学特征[J].地质通报,2014,33(7):984-994.Zhang X F,Li Y G,Cao X M,et al.LA-ICP-MSzircon U-Pb age and geochemical characteristics of the acid intrusive rocks in the western part of Bangong Lake-Nujiang River suture zone[J].Geologocal Bulletin of China,2014,33(7):984-994.(in Chinese)
[14]侯可军,李延河,田有荣.LA-MC-ICP-MS锆石微区原位U-Pb定年技术[J].矿床地质,2009,28(4):481-492.Hou K J,Li Y H,Tian Y R.In situ U-Pb zircon dating using laser ablation-multi ion counting-ICP-MS[J].Mineral Deposit,2009,28(4):481-492.(in Chinese)
[15]Slama J,Kosler J,Condon D J,et al.Plesovice zircon-A new natural reference material for U-Pb and Hf isotopic microanalysis[J].Chemical Geology,2008,249:1-35.
[16]Loiselle M C,Wones D R.Characteristics and origin of anorogenic granites[J].Geological Society of America,1979,11(7):468.
[17]Chappell B W,White A J R.Two contrasting granite types[J].Pac Geol,1974,8:173-174.
[18]Eby G N.The A-type granitoids:A review of their occurrence and chemical characteristics and speculations on their petrogensis[J].Lithos,1990,26(1/2):115-134.
[19]Collins W J,Beams S D,White A J R,et al.Nature and origin of A-type granite with particular reference to southeast Australia[J].Contrib Mineral Petrol,1982,80(2):189-200.
[20]Pearce J A,Harris N B W,Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].J Petrol,1984,25(4):956-983.
[21]Batchelor R A,Bowden P.Petrogenetic interpretation of granitiod rock series using multicationic parameters[J].Chem Geol,1985,48(1/2/3/4):43-55.
[22]曲晓明,辛洪波,杜德道,等.西藏班公湖-怒江缝合带中段碰撞后A型花岗岩的时代及其对洋盆闭合时间的约束[J].地球化学,2012,41(1):1-14.Qu X M,Xin H B,Du D D,et al.Ages of postcollisional A-type granite and constraint on the closure of the oceanic basin in the middle segment of the Bangonghu-Nujiang suture,the Tibet plateau[J].Geochimica,2012,41(1):1-14.(in Chinese)
[23]Eby G N.Chemical subdivision of the A-type granitiods:Petrogenetic and tectonic implications[J].Geology,1992,20(7):641-644.
[24]Dargahi S,Arvin M,Pan Y M,et al.Petrogensis of post-collisional A-type granitiods from the Urumieh-Dokhtar magmatic assemblage,southwestern Kerman,Iran:Constraints on the ArabianEurasian continental collision[J].Lithos,2010,115(1/2/3/4):190-204.
[25]莫宣学,潘桂棠.从特提斯到青藏高原形成:构造-岩浆事件的约束[J].地学前缘,2006,13(6):43-51.Mo X X,Pan G T.From the Tethys to the formation of the Qinghai-Tibet Plateau:Constrained by tectono-magmatic events[J].Earth Science Frontiers,2006,13(6):43-51.(in Chinese)
[26]张玉修.班公湖-怒江缝合带中西段构造演化[D].广州:中国科学院广州地球化学研究所,2007:1-257.Zhang Y X.Tectonic Evolution of the MiddleWestern Bangong-Nujiang Suture,Tibet[D].Guangzhou:Guangzhou Institute of Geochemistry of the Chinese Academy of Science,2007:1-257.(in Chinese)
[27]赵元艺,崔玉斌,吕丽娜,等.西藏舍索矽卡岩型铜多金属矿床年代学与地球化学特征及意义[J].岩石学报,2011,27(7):2132-2142.Zhao Y Y,Cui Y B,Lyu L N,et al.Chronology,geochemical characteristic and the significance of Shesuo copper polymetallic deposit,Tibet[J].Acta Petrologica Sinica,2011,27(7):2132-2142.(in Chinese)
[28]陈国荣,刘鸿飞,蒋光武,等.西藏班公湖-怒江结合带中段沙木罗组的发现[J].地质通报,2004,23(2):193-194.Chen G R,Liu H F,Jiang G W,et al.Discovery of the Shamuluo Formation in the central segment of the Bangongcuo-Nujiang suture zone,Tibet[J].Geol Bull China,2004,23(2):193-194.(in Chinese)
© 2004-2018 中国地质图书馆版权所有 京ICP备05064691号 京公网安备11010802017129号 地址：北京市海淀区学院路29号 邮编：100083 电话：办公室：(+86 10)66554848；文献借阅、咨询服务、科技查新：66554700 |