东天山双龙铜矿石英闪长岩锆石U-Pb定年、Hf同位素分析及对构造环境的制约
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摘要
通过对新疆东天山雅满苏岛弧带双龙铜矿成岩地质特征、岩石地球化学特征及Hf同位素分析,认为赋矿岩体为一套形成于后碰撞环境下的准铝质高钾钙碱性岩石系列的石英闪长岩,LA-ICP-MS锆石U-Pb同位素年龄为(300.9±1.2)Ma。岩石地球化学显示,赋矿岩石具富集大离子亲石元素(LILE)K,Rb等及高场强元素(HFSE)Th,U,Zr和Hf,贫Nb,Ta,Ti,Sr,P特征,可能形成于后碰撞构造环境。石英闪长岩锆石~(176)Hf/~(177)Hf变化范围0.282 949～0.283 002,平均值0.282 979,εHf(t)值为12.32～14.40,平均13.40,tDM2(Hf)为375～482 Ma,平均429 Ma,表明岩浆物源可能来自志留纪新生地壳的部分熔融。
Through the study of quartz diorite geological characteristics, rock geochemical characteristics and Hf isotope analysis of the Shuanglong copper deposit in Yamansu island area,it is concluded that the mineralized rock mass is a set of quartz dendrites formed in the series of quasi-aluminum high potassium calcium alkaline rocks in the post-collision environment.Its LA-ICP-MS zircon U-Pb isotope age is(300.9 ±1.2) Ma(late Late Carboniferous), representing the crystallization age of magma.Through rock geochemistry analysis,it is concluded that the mineralized rocks have the characteristics of rich Cs, Rb, Ba and other large Ionic prostony elements, and high field strong elements Nb,Ta,Ti,Sr,P are obviously losing.The geochemical characteristics of the island arc magmatic rock may be formed in the post-collision tectonic environment. The variation of quartz diorite zircon ~(176)Hf/~(177)Hf ranged from 0.282 949 to 0.283 002 with an average value of 0.282 979. The value of εHf(t) was 12.32～14.40, the average was 13.40, and the tDM2(Hf) was 375 ～ 482 Ma,the average was 429 Ma(middle Silurian), it is indicated that the source of magmatic material may come from the mixing of the Silurian strata.
Through the study of quartz diorite geological characteristics, rock geochemical characteristics and Hf isotope analysis of the Shuanglong copper deposit in Yamansu island area,it is concluded that the mineralized rock mass is a set of quartz dendrites formed in the series of quasi-aluminum high potassium calcium alkaline rocks in the post-collision environment.Its LA-ICP-MS zircon U-Pb isotope age is(300.9 ±1.2) Ma(late Late Carboniferous), representing the crystallization age of magma.Through rock geochemistry analysis,it is concluded that the mineralized rocks have the characteristics of rich Cs, Rb, Ba and other large Ionic prostony elements, and high field strong elements Nb,Ta,Ti,Sr,P are obviously losing.The geochemical characteristics of the island arc magmatic rock may be formed in the post-collision tectonic environment. The variation of quartz diorite zircon ~(176)Hf/~(177)Hf ranged from 0.282 949 to 0.283 002 with an average value of 0.282 979. The value of εHf(t) was 12.32～14.40, the average was 13.40, and the tDM2(Hf) was 375 ～ 482 Ma,the average was 429 Ma(middle Silurian), it is indicated that the source of magmatic material may come from the mixing of the Silurian strata.
引文
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(1)新疆地质调查院.新疆鄯善县灵北地区1∶5万K46E013005、K46E013006二幅区域地质调查成果报告,2018
[2]Qin Kezhang,Sun Shu,Li Jiliang,Fang Tonghui,Wang Shulai,Liu Wei.Paleozoic Epithermal Au and Porphyry Cu Deposits in North Xinjiang,China:Epochs,Features,Tectonic Linkage and Exploration Significance[J].Resource Geology.2002,52(4):291-300.
[3]芮宗瑶,刘玉琳,王龙生,等.新疆东天山斑岩型铜矿带及其大地构造格局[J].地质学报,2002,76(1):83-92.
[4]Yang Fuquan,Mao Jingwen,Frank p.Bierlein,Franco Pirajno,ZHAO Caisheng,YE Huishou,LIU Feng.A review of the geological characteristics and geodynamic mechanisms of Late Paleozoic epithermal gold deposits in North Xinjiang,China[J].Ore Geology Reviews.2009,35:217-234.
[5]顾连兴,张遵忠,吴昌志,等.关于东天山花岗岩与陆壳垂向增生的若干认识[J].岩石学报,2006,22(5):1103-1120.
[6]肖文交,韩春明,袁超,等.新疆北部石炭纪-二叠纪独特的构造-成矿作用:对古亚洲洋构造域南部大地构造演化的制约[J].岩石学报,2006,22(5):1062-1076.
[7]吴昌志,张遵忠,Khin Zaw,等.东天山觉罗塔格红云滩花岗岩年代学、地球化学及其构造意义[J].岩石学报,2006,22(5):1121-1134.
[8]朱永峰.新疆的印支运动与成矿[J].地质通报,2007,26(5):510-519.
[9]董连慧,冯京,刘德权,等.新疆成矿单元划分方案研究[J].新疆地质,2010,28(1):1-15.
[10]周涛发,袁峰,张达玉,等.新疆东天山觉罗塔格地区花岗岩类年代学、构造背景及其成矿作用研究[J].岩石学报,2010,26(2):478-502.
[11]Liu Y S,Hu Z C,Zong K Q,Gao C G,Gao S,Xu J,Chen H H.Reappraisement and refinement of zircon U-Pb isotope and trace element analyses by LA-ICP-MS.Chinese Sci[J].Bull,2010,55(15):1535-1546.
[12]Ludwig K R.Isoplot/Ex version 3.0.A geochronological toolkit for Microsoft Excel.Berkeley Geochron.Centre Spec,2003,4:1-70.
[13]Taylor S R,McLennan S M.The Continental Crust:Its Composition and Evolution[J].Oxford,Blackwell,1985,312.
[14]Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalt:implications for mantle composition and processes.In:Saunders A D and Norry M J(eds),Magmatism in the Ocean Basins[J].Geological Society,London,Special Publications,1989,42:313-345.
[15]Amelin Y,Lee D C,Halliday A N.Early-Middle Archean crustal evolution deduced from Lu-Hf and U-Pb isotopic studies of single zircon grains[J].Geochimica et Cosmochimica Acta,2000,64:4205-4225.
[16]Vervoort J D,Pachelt P J,Gehrels G E and Nutman A P.Constraints on early Earth differentiation from hafnium and neodymium isotopes[J].Nature,1996,379:624-627.
[17]Sǒderlund U,Patchett P J,Vervoort J D and Isachsen C E.The176Ludecay constant detrmined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusins[J].Earth and Plantry Science Letters,2004,219:311-324.
[18]Blichert-Tofy J,Albarède F.The Lu-Hf Geochemistry of chondrites and evolution of the mantle-crust system[J].Earth Planetary Science Letters,1997,148:243-258.
[19]Zhou T.F,Yuan F,Fan Y,Zhang D.Y,David C,Zhao G.C.Granites in theSawuer region of the west Junggar,Xinjiang Province,China:geochronologicaland geochemical characteristics and their geodynamic signicance[J].Lithos,2008,106,191-206.
[20]张达玉,周涛发,袁峰,等.新疆东天山觉罗塔格地区自然铜矿化玄武岩的成岩年代及其地质意义[J].岩石学报,2012.28(8):2392-2400.
[21]袁峰,周涛发,张达玉,等.东天山自然铜矿化带玄武岩的起源、演化及成岩构造背景[J].岩石学报,2010,26(2):533-546.
[22]Pearce J A,Harris N B W and Tindle A G.Trace element discrimination diagrams for the tectonic interpretation of granitic rocks[J].Jorunal of Petrology.1984,25:956-983.
[23]Batchelor R A,Bowden P.Petrogenetic interpretation of granitoid rock series using multicationic parameters[J].Chem.Geol,1985,48:43-55.
(1)新疆地质调查院.新疆鄯善县灵北地区1∶5万K46E013005、K46E013006二幅区域地质调查成果报告,2018