西藏谢通门县查布地区中新世火山岩LA-ICP-MS锆石U-Pb年龄及其地质意义
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摘要
西藏地勘局地质二队在谢通门县查布地区1∶5万区域地质调查中新解体出一套火山岩地层,其岩性以安山岩、流纹岩、火山角砾岩及凝灰岩为主,岩层总厚度在研究区由东向西减小。用LA-ICP-MS技术对流纹岩、安山岩2件样品中的锆石进行U-Pb同位素测定,其~(206)Pb/~(238)U年龄加权平均值分别为:流纹岩中有2组年龄15.12±0.29Ma(MSWD=1.8,n=8)、45.39±0.56Ma(MSWD=0.93,n=14),安山岩中有4组年龄15.29±0.16Ma(MSWD=1.4,n=59)、51.9±2.3Ma(MSWD=3.5,n=7)、45.2±1.4Ma(MSWD=3.8,n=10)、38.5±0.93Ma(MSWD=1.08,n=5)。据此将该套火山岩喷发时限确定为15Ma左右,划归于布嘎寺组。
The No.2 Geobrigade of Tibet Geological Prospecting Bureau has disintegrated a set of volcanic rocks in the 1∶50 thousand regional geological survey of the chubb area of Xietongmen county. It composed dominantly of andesite, rhyolite, volcanic breccia and tuff. The total thickness of the rock strata decreases from east to west in the study area. The U-Pb isotopes of zircons from rhyolite and andesite samples were determined by LA-ICP-MS. The weighted average ages of ~(206)Pb/~(238)U were 15.12±0.29 Ma(MSWD=1.8, n=8), 45.39 ± 0.56 Ma(MSWD=0.93, n=14) in rhyolite and 15.29 ± 0.16 Ma(MSWD=1.4, n=59), 51.9 ± 2.3 Ma(MSWD=3.5, n= 7), 45.2±1.4 Ma(MSWD=3.8, n=10), 38.5±0.93 Ma(MSWD=1.08, n=5) in andesite. Based on this, the eruption time limit of this suite of volcanic rocks is determined to be 15 Ma or so, and it belongs to the Bugasi Group.
The No.2 Geobrigade of Tibet Geological Prospecting Bureau has disintegrated a set of volcanic rocks in the 1∶50 thousand regional geological survey of the chubb area of Xietongmen county. It composed dominantly of andesite, rhyolite, volcanic breccia and tuff. The total thickness of the rock strata decreases from east to west in the study area. The U-Pb isotopes of zircons from rhyolite and andesite samples were determined by LA-ICP-MS. The weighted average ages of ~(206)Pb/~(238)U were 15.12±0.29 Ma(MSWD=1.8, n=8), 45.39 ± 0.56 Ma(MSWD=0.93, n=14) in rhyolite and 15.29 ± 0.16 Ma(MSWD=1.4, n=59), 51.9 ± 2.3 Ma(MSWD=3.5, n= 7), 45.2±1.4 Ma(MSWD=3.8, n=10), 38.5±0.93 Ma(MSWD=1.08, n=5) in andesite. Based on this, the eruption time limit of this suite of volcanic rocks is determined to be 15 Ma or so, and it belongs to the Bugasi Group.
引文
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[34]张丽,黄勇,李光明,等.西藏朱诺斑岩铜矿石英闪长斑岩锆石LA-ICP-MSU-Pb定年及Lu-Hf同位素研究[J].矿物学报,2016,36(1):143-149.
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[2]马润则,刘登忠,陶晓风,等.西藏措勤地区发现第三纪富钾岩浆岩[J].地质通报,2002,21(11):728-731.
[3]廖思平,陈振华,罗小川,等.西藏当惹雍错地区白榴石响岩的发现及地质意义[J].地质通报,2002,21(11):735-738.
[4]周肃,莫宣学,赵志丹,等.西藏南部羊应乡后碰撞火山岩40Ar-39Ar年龄及其地质意义[J].然科学进展,2004,14(12):1411-1418.
[5]Williams H,Tumer S,Kelley S,et al.Age and composition of dikes in Southern Tibet:New constraints on the timing of east-west extension and its relationship to post-collisional volcanism[J].Geology,2001,29:339-342.
[6]Ding L,Kapp P,Zhong D,et al.Cenozoic colcanism in Tibet:Evidence for a transition from oceanic to continental subduction[J].J.Petrol.,2003,44(10):1833-1865.
[7]Nomade S,Renne P R,Mo X,et al.Miocene potassic and ultrapotassic volcanism in the Lhasa block:Spatial trends and geodynamic implications[J].Earth Planet.Sci.Lett.,2004,221:227-243.
[8]应立娟.西藏甲玛铜多金属矿床的成矿机制[D].中国地质科学院博士学位论文,2012:123-137.
[9]林武,梁华英,张玉泉,等.冈底斯铜矿带冲江含矿斑岩的岩石化学及锆石SHRIMP年龄特征[J].地球化学,2004,33(6):585-592.
[10]芮宗瑶,侯增谦,李光明,等.冈底斯斑岩铜矿成矿模式[J].地质论评,2006,(4):459-466.
[11]孟祥金,侯增谦,高永丰,等.西藏冈底斯成矿带驱龙铜矿ReOs年龄及成矿学意义[J].地质论评,2003,49(6):660-666.
[12]李光明,芮宗瑶.西藏冈底斯成矿带斑岩铜矿的成岩成矿年龄[J].大地构造与成矿学,2004,28(2):165-170.
[13]郑有业,张刚阳,许荣科,等.西藏冈底斯朱诺斑岩铜矿床成岩成矿时代约束[J].科学通报,2007,52(21):2542-2548.
[14]成都理工大学地调院.1∶25万赛利普幅地质调查成果与进展[J].沉积与特提斯地质,2005,(Z1):87-90.
[15]李光明,冯孝良,黄志英,等.西藏冈底斯构造带中段多岛弧-盆系及其演化[J].沉积与特提斯地质,2000,20(4):38-46.
[16]Liu Y,Gao S,Hu Z,et al.Continental and oceanic crust recyclinginduced melt-peridotite interactions in the Trans-North China Orogen:U-Pb dating,Hf isotopes and trace elements in zircons of mantle xenoliths[J].Journal of Petrology,2010,51:537-571.
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[18]潘桂棠.青藏高原及邻区大地构造图及说明书[M].北京:地质出版社,2013.
[19]西藏自治区地质矿产局.西藏自治区区域地质志[M].北京:地质出版社,1993.
[20]夏代祥,刘世坤.西藏自治区岩石地层[M].武汉:中国地质大学出版社,2008.
[21]Yin A,Harrison T M.Geologic evolution of the HimalayanTibetan orogen[J].Annual Reviews of Earth and Planet.Sci.,2000,28:211-280.
[22]Tapponnier P,Xu Z,Roger F,et al.Oblique stepwise rise and growth of the Tibet Plateau[J].Science,2001,(294):1671-1677.
[23]李兴奎,李才,王明,等.藏北多龙矿集区地壳基底性质、演化及其对成矿的制约--来自波龙火山-侵入岩中继承锆石U-Pb年龄的信息[J].地质通报,2018,37(8):1439-1449.
[24]闫国川,王保弟,刘函,等.西藏洞错埃达克质火山岩LA-ICP-MS锆石U-Pb年龄及其构造意义[J].地质通报,2017,36(10):1772-1782.
[25]Maheo G,Guillot S,Blichert-Toft,et al.A slab breakoff model for the Neogene thermal evolution of south Karakorum and south Tibet[J].Earth Planet.Sci.Lett.,2002,(195):45-58.
[26]董国臣,莫宣学,赵志丹,等.冈底斯带西段那木如岩体始新世岩浆作用及构造意义[J].岩石学报,2011,27(7):1983-1992.
[27]Dong G C,Mo X X,Zhao Z D,et al.Geochronologic constraints by SHRIMPⅡzircon U-Pb dating on magma underplating in the Gangdise belt following India-Eurasia collision[J].Acta Geologica Sinica,2005,79:787-794.
[28]Wen D R,Liu D Y,Chu M F,et al.Zircon SHRIMP U-Pb ages of the Gangdese Batholith and implications for Neo-tethyan subduction in southern Tibet[J].Chemical Geology,2008,252:191-201.
[29]莫宣学,董国臣,赵志丹,等.西藏冈底斯带花岗岩的时空分布特征及地壳生长演化信息[J].高校地质学报,2005,11(3):281-290.
[30]孟元库,许志琴,高存山,等.藏南冈底斯带中段始新世岩浆作用的厘定及其大地构造意义[J].岩石学报,2018,34(3):513-546.
[31]孟元库,许志琴,陈希节,等.藏南冈底斯中段谢通门始新世复式岩体锆石U-Pb年代学、Hf同位素特征及其地质意义[J].大地构造与成矿学,2015,39(5):933-948.
[32]侯增谦,莫宣学,杨志明,等.青藏高原碰撞造山带成矿作用:构造背景、时空分布和主要类型[J].中国地质,2006,33(2):340-351.
[33]芮宗瑶,侯增谦,曲晓明,等.冈底斯斑岩铜矿成矿时代及青藏高原隆升[J].矿床地质,2003,22(3):217-225.
[34]张丽,黄勇,李光明,等.西藏朱诺斑岩铜矿石英闪长斑岩锆石LA-ICP-MSU-Pb定年及Lu-Hf同位素研究[J].矿物学报,2016,36(1):143-149.
[35]王登红.中国新生代成矿作用[M].北京:地质出版社,2005.