青海都兰县阿斯哈石英闪长岩岩石地球化学、锆石U-Pb年龄与Hf同位素特征
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摘要
都兰县阿斯哈石英闪长岩体呈岩基状产出。闪长岩全岩样品具有低SiO_2(56.82%～61.15%)、富碱(Na_2O+K_2O为5.31%～6.02%)、低TFeO(6.09%～6.65%)和低TiO_2(1.02%～1.25%)含量特征,属高钾钙碱性系列岩石。岩石中Cr(24.6×10~(-6)～47.6×10~(-6))和Ni(12.8×10~(-6)～17.6×10~(-6))含量不高,K、Ba、Rb、Th、U等大离子亲石元素富集,而Nb、Ta、P、Ti等高场强元素亏损,具有岛弧或活动大陆边缘弧岩浆的特征。用LA-ICP-MS测得锆石~(206)Pb/~(238)U年龄为232.6±1.4Ma,表明岩体为中三叠世形成。锆石具有明显偏低的εHf(t)值(-3.71～-0.84,平均为-2.31,t=232.6Ma)和偏老的t2DM年龄(1.32～1.50Ga,平均为1.41Ga),表明岩浆来源于古老地壳物质的熔融,很可能为研究区中元古代俯冲地壳物质。阿斯哈石英闪长岩的源区具有壳-幔混合特征,是幔源基性岩浆与古老壳源花岗质岩浆混合作用的产物,岩石形成于中三叠世晚期俯冲向碰撞转换的动力学背景下,代表东昆仑晚古生代—早中生代造山过程的岩浆记录。
The Asiha diorite in Dulan County is batholith shaped output. The whole rock samples have characteristics by SiO_2(56.82% ～61.15%), rich alkali(Na_2O+K_2O=5.31%～6.02%), low total iron(TFeO=6.09%～6.65%) and low TiO_2(1.02%～1.25%).Therefore, the diorite belongs to of high-K calc-alkaline rocks. The values of Cr(24.6×10~(-6)～ 47.6×10~(-6)) and Ni(12.8×10~(-6)～17.6×10~(-6)) are not high. The diorite is enriched in the LILE such as K, Ba, Rb, Th, U and LREE and depleted in HFSE such as Nb, Ta, P and Ti. LA-ICP-MS zircon U-Pb dating results show that the crystallization age of the diorite is 232.6+1.4 Ma, and the age belongs to the Middle Triassic. The zircons have relatively low ε_(Hf)(t) values(t=232 Ma, ε_(Hf)(t)=-3.71～-0.84,-2.31 on average) and relatively old t_(2DM)(1.32～1.50 Ga, 1.41 Ga on average), thus the magma should be derived from Proterozoic subducted crust. In summary, the magma had crust-mantle mixing characteristics, and the diorite was mainly derived from granitic magma of crust(Proterozoic subducted crust) and experienced activity of basic magma of the mantle. The rock was formed under the geodynamic background of conversion from subduction to collision, which represented the magma records of oceanic crust subduction from Late Paleozoic to Early Mesozoic in East Kunlun.
The Asiha diorite in Dulan County is batholith shaped output. The whole rock samples have characteristics by SiO_2(56.82% ～61.15%), rich alkali(Na_2O+K_2O=5.31%～6.02%), low total iron(TFeO=6.09%～6.65%) and low TiO_2(1.02%～1.25%).Therefore, the diorite belongs to of high-K calc-alkaline rocks. The values of Cr(24.6×10~(-6)～ 47.6×10~(-6)) and Ni(12.8×10~(-6)～17.6×10~(-6)) are not high. The diorite is enriched in the LILE such as K, Ba, Rb, Th, U and LREE and depleted in HFSE such as Nb, Ta, P and Ti. LA-ICP-MS zircon U-Pb dating results show that the crystallization age of the diorite is 232.6+1.4 Ma, and the age belongs to the Middle Triassic. The zircons have relatively low ε_(Hf)(t) values(t=232 Ma, ε_(Hf)(t)=-3.71～-0.84,-2.31 on average) and relatively old t_(2DM)(1.32～1.50 Ga, 1.41 Ga on average), thus the magma should be derived from Proterozoic subducted crust. In summary, the magma had crust-mantle mixing characteristics, and the diorite was mainly derived from granitic magma of crust(Proterozoic subducted crust) and experienced activity of basic magma of the mantle. The rock was formed under the geodynamic background of conversion from subduction to collision, which represented the magma records of oceanic crust subduction from Late Paleozoic to Early Mesozoic in East Kunlun.
引文
[1]李碧乐,孙丰月,于晓飞,等.东昆中隆起带东段闪长岩U-Pb年代学和岩石地球化学研究[J].岩石学报,2012,28(4):1163-1172.
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[3]莫宣学,罗照华,邓晋福,等.东昆仑造山带花岗岩及地壳生长[J].高校地质学报,2007,13(3):403-414.
[4]姜春发,杨经绥,冯秉贵,等.昆仑开合构造[M].北京:地质出版社,1992:183-217.
[5]姜春发,王宗起,李锦轶.中央造山带开合构造[M].北京:地质出版社,2000:1-54.
[6]郭正府,邓晋福,许志琴,等.青藏东昆仑晚古生代末-中生代中酸性火成岩与陆内造山过程[J].现代地质,1998,12(3):344-352.
[7]罗照华,邓晋福,曹永清,等.青海省东昆仑地区晚古生代-早中生代火山活动与区域构造演化[J].现代地质,1999,13(1):51-56.
[8]崔军文,朱红,武长得.青藏高原岩石圈变形及其动力学[M].北京:地质出版社,1992:1-164.
[9]殷鸿福,张克信.东昆仑造山带的一些特点[J].地球科学--中国地质大学学报,1997,22(4):339-342.
[10]殷鸿福,张克信.中央造山带的演化及其特点[J].地球科学--中国地质大学学报,1998,23(5):437-441.
[11]王国灿,魏启荣,贾春兴,等.关于东昆仑地区前寒武纪地质的几点认识[J].地质通报,2007,26(8):929-937.
[12]岳维好,高建国,周家喜.青海果洛龙洼金矿基性岩脉锆石U-Pb年龄及岩石地球化学特征[J].矿物岩石,2013,33(3):93-102.
[13]岳维好,周家喜,高建国,等.青海都兰县色德日辉绿岩地球化学特征、锆石U-Pb年龄及其地质意义[J].矿物岩石地球化学通报,2017,26(2):270-278.
[14]岳维好,周家喜,高建国,等.青海都兰县阿斯哈金矿区花岗斑岩岩石地球化学、锆石U-Pb年代学与Hf同位素研究[J].大地构造与成矿学,2017,41(4):776-789.
[15]Qi L,Hu J,Gregoire D C.Determination of trace elements in granites by inductively coupled plasma mass spectrometry[J].Talanta,2000,51(3):507-513.
[16]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.
[17]Liu Y S,Hu Z C,Gao S,et al.In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[J].Chemical Geology,2008,257(1/2):34-43.
[18]Ludwig K R.Isoplot 3.0:A geochronological toolkit for Microsoft Excel[J].Berkeley:Berkeley Geochronology Center Special Publication,2003:1-70.
[19]Wu F Y,Yang Y H,Xie L W,et al.Hf isotopic compositions of the standard zircons and baddeleyites used in U-Pb geochronology[J].Chemical Geology,2006,234:105-126.
[20]Goolaerts A,Mattielli N,De Jong J,et al.Hf and Lu isotopic reference values for the zircon standard 91500 by MC-ICP-MS[J].Chemical Geology,2004,206:1-9.
[21]Woodhead J,Hergt J,Shelley M,et al.Zircon Hf-isotope analysis with an excimer laser,depth profiling,ablation of complex geometries,and concomitant age estimation[J].Chemical Geology,2004,20:121-135.
[22]Blichert Toft J,Albarède F.The Lu-Hf geochemistry of chondrites and evolution of the mantle-crust system[J].Earth and Planetary Science Letters,1998,148:243-258.
[23]Griffin W L,Pearson N J,Belousova E,et al.The Hf isotope composition of cratonic mantle:LA-MC-ICPMS analysis of zircon megacrysts in kimberlites[J].Geochimia et Cosmochimica Acta,2003,64:133-147.
[24]Peccerillo R,Talor S R.Geochemistry of Eocene cal-alkaline vaocanic rocks from the Kastamonu area,northern Turkey[J].Contrib.Mineral.Petrol.,1976,58:63-81.
[25]Maniar P D,Piccoli P M.Tectonic discrimination of granitoids[J].Geological Society of America Bulletin,1989,101:635-643.
[26]Boynton W V.Cosmochemistry of the rare earth elements:Meteorite studies[C]//Henderson P.Rare Earth Element Geochemistry.Developments in Geochemistry 2.Amsterdam:Elsevier,1984:63-114.
[27]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[C]//Saunders A D,Norry M J.Magmatism in Oceanic Basins.Spec.Publ.Geol.Soc.Lond.,1989,42:313-345.
[28]Belousova E A,Griffin W L,O’Reilly S Y.Igneous zircon:Trace element composition as an indicator of source rock type[J].Contrib.Mineral.Petrol.,2002,143:602-622.
[29]S?derlund U,Pathcett P J,Verrot J D,et al.The176Lu decay contant determined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusion[J].Earth and Planetary Scicence Letters,2004,219:311-324.
[30]吴福元,李献华,郑永飞,等.Lu-Hf同位素体系及其岩石学应用[J].岩石学报,2007,23(2):185-220.
[31]Taylor S R,McLennan S M.The geochemical evolution of the continental crust[J].Reviews of Geophysics,1995,33(2):241-265.
[32]Griffin W L,Wang X,Jackon S E,et al.Zircon chemistry and magma genesis,SE China:In-situ analysis of Hf isotopes,Tonglu and Pingtan igneous complexes[J].Lithos,2002,61:237-269.
[33]Kemp A I S,Hawkesworth C J,Foster G L,et al.Magmatic and crustal differentiation history of granitic rocks from Hf-O Isotopes in Zircon[J].Science,2007,16:980-983.
[34]Batchelor R A,Bowden P.Petrorgenetic interpretation of granitoid rock series using multicationic parameters[J].Chemistry Geology,1985,50:63-81.
[35]Condie K C.Geochemical changes in baslts and andesites across the Archean-Proterozoic boundary:Identification and significance[J].Lithos,1989,23:1-18.
[36]Salters V J M,Hart S R.The mantle sources of ocean ridges,island arcs:The Hf-isotope connection[J].Earth Planet.Sci.Lett.,1991,104:364-380.
[37]Yang J S,Robinson P T,Jiang C F,et al.Ophiolites of the Kunlun Mountains,China and their tectonic implications[J].Tectonolphysics,1996,258(1/4):215-231.
[38]杨经绥,许志琴,李海兵,等.东昆仑阿尼玛卿地区古提特斯火山作用和板块构造体系[J].岩石矿物杂志,2005,24(5):369-380.
[39]熊富浩,马昌前,张金阳,等.东昆仑造山带早中生代镁铁质岩墙群LA-ICP-MS锆石U-Pb定年、元素和Sr-Nd-Hf同位素地球化学[J].岩石学报,2011,27(11):3350-3364.
(1)长安大学和青海省有色地质八队.青海省都兰县沟里地区Ⅰ47 E003010(沟里乡)1∶5万矿产地质、水系沉积物测量综合调查成果报告. 2007.
(2)青海省地质局. 1∶20万加鲁河幅区域地质调查报告. 1973.
[2]许志琴,杨经绥,李海兵,等.中央造山带早古生代地体构架与高压/超高压变质带的形成[J].地质学报,2006,80(12):1793-1806.
[3]莫宣学,罗照华,邓晋福,等.东昆仑造山带花岗岩及地壳生长[J].高校地质学报,2007,13(3):403-414.
[4]姜春发,杨经绥,冯秉贵,等.昆仑开合构造[M].北京:地质出版社,1992:183-217.
[5]姜春发,王宗起,李锦轶.中央造山带开合构造[M].北京:地质出版社,2000:1-54.
[6]郭正府,邓晋福,许志琴,等.青藏东昆仑晚古生代末-中生代中酸性火成岩与陆内造山过程[J].现代地质,1998,12(3):344-352.
[7]罗照华,邓晋福,曹永清,等.青海省东昆仑地区晚古生代-早中生代火山活动与区域构造演化[J].现代地质,1999,13(1):51-56.
[8]崔军文,朱红,武长得.青藏高原岩石圈变形及其动力学[M].北京:地质出版社,1992:1-164.
[9]殷鸿福,张克信.东昆仑造山带的一些特点[J].地球科学--中国地质大学学报,1997,22(4):339-342.
[10]殷鸿福,张克信.中央造山带的演化及其特点[J].地球科学--中国地质大学学报,1998,23(5):437-441.
[11]王国灿,魏启荣,贾春兴,等.关于东昆仑地区前寒武纪地质的几点认识[J].地质通报,2007,26(8):929-937.
[12]岳维好,高建国,周家喜.青海果洛龙洼金矿基性岩脉锆石U-Pb年龄及岩石地球化学特征[J].矿物岩石,2013,33(3):93-102.
[13]岳维好,周家喜,高建国,等.青海都兰县色德日辉绿岩地球化学特征、锆石U-Pb年龄及其地质意义[J].矿物岩石地球化学通报,2017,26(2):270-278.
[14]岳维好,周家喜,高建国,等.青海都兰县阿斯哈金矿区花岗斑岩岩石地球化学、锆石U-Pb年代学与Hf同位素研究[J].大地构造与成矿学,2017,41(4):776-789.
[15]Qi L,Hu J,Gregoire D C.Determination of trace elements in granites by inductively coupled plasma mass spectrometry[J].Talanta,2000,51(3):507-513.
[16]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.
[17]Liu Y S,Hu Z C,Gao S,et al.In situ analysis of major and trace elements of anhydrous minerals by LA-ICP-MS without applying an internal standard[J].Chemical Geology,2008,257(1/2):34-43.
[18]Ludwig K R.Isoplot 3.0:A geochronological toolkit for Microsoft Excel[J].Berkeley:Berkeley Geochronology Center Special Publication,2003:1-70.
[19]Wu F Y,Yang Y H,Xie L W,et al.Hf isotopic compositions of the standard zircons and baddeleyites used in U-Pb geochronology[J].Chemical Geology,2006,234:105-126.
[20]Goolaerts A,Mattielli N,De Jong J,et al.Hf and Lu isotopic reference values for the zircon standard 91500 by MC-ICP-MS[J].Chemical Geology,2004,206:1-9.
[21]Woodhead J,Hergt J,Shelley M,et al.Zircon Hf-isotope analysis with an excimer laser,depth profiling,ablation of complex geometries,and concomitant age estimation[J].Chemical Geology,2004,20:121-135.
[22]Blichert Toft J,Albarède F.The Lu-Hf geochemistry of chondrites and evolution of the mantle-crust system[J].Earth and Planetary Science Letters,1998,148:243-258.
[23]Griffin W L,Pearson N J,Belousova E,et al.The Hf isotope composition of cratonic mantle:LA-MC-ICPMS analysis of zircon megacrysts in kimberlites[J].Geochimia et Cosmochimica Acta,2003,64:133-147.
[24]Peccerillo R,Talor S R.Geochemistry of Eocene cal-alkaline vaocanic rocks from the Kastamonu area,northern Turkey[J].Contrib.Mineral.Petrol.,1976,58:63-81.
[25]Maniar P D,Piccoli P M.Tectonic discrimination of granitoids[J].Geological Society of America Bulletin,1989,101:635-643.
[26]Boynton W V.Cosmochemistry of the rare earth elements:Meteorite studies[C]//Henderson P.Rare Earth Element Geochemistry.Developments in Geochemistry 2.Amsterdam:Elsevier,1984:63-114.
[27]Sun S S,McDonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[C]//Saunders A D,Norry M J.Magmatism in Oceanic Basins.Spec.Publ.Geol.Soc.Lond.,1989,42:313-345.
[28]Belousova E A,Griffin W L,O’Reilly S Y.Igneous zircon:Trace element composition as an indicator of source rock type[J].Contrib.Mineral.Petrol.,2002,143:602-622.
[29]S?derlund U,Pathcett P J,Verrot J D,et al.The176Lu decay contant determined by Lu-Hf and U-Pb isotope systematics of Precambrian mafic intrusion[J].Earth and Planetary Scicence Letters,2004,219:311-324.
[30]吴福元,李献华,郑永飞,等.Lu-Hf同位素体系及其岩石学应用[J].岩石学报,2007,23(2):185-220.
[31]Taylor S R,McLennan S M.The geochemical evolution of the continental crust[J].Reviews of Geophysics,1995,33(2):241-265.
[32]Griffin W L,Wang X,Jackon S E,et al.Zircon chemistry and magma genesis,SE China:In-situ analysis of Hf isotopes,Tonglu and Pingtan igneous complexes[J].Lithos,2002,61:237-269.
[33]Kemp A I S,Hawkesworth C J,Foster G L,et al.Magmatic and crustal differentiation history of granitic rocks from Hf-O Isotopes in Zircon[J].Science,2007,16:980-983.
[34]Batchelor R A,Bowden P.Petrorgenetic interpretation of granitoid rock series using multicationic parameters[J].Chemistry Geology,1985,50:63-81.
[35]Condie K C.Geochemical changes in baslts and andesites across the Archean-Proterozoic boundary:Identification and significance[J].Lithos,1989,23:1-18.
[36]Salters V J M,Hart S R.The mantle sources of ocean ridges,island arcs:The Hf-isotope connection[J].Earth Planet.Sci.Lett.,1991,104:364-380.
[37]Yang J S,Robinson P T,Jiang C F,et al.Ophiolites of the Kunlun Mountains,China and their tectonic implications[J].Tectonolphysics,1996,258(1/4):215-231.
[38]杨经绥,许志琴,李海兵,等.东昆仑阿尼玛卿地区古提特斯火山作用和板块构造体系[J].岩石矿物杂志,2005,24(5):369-380.
[39]熊富浩,马昌前,张金阳,等.东昆仑造山带早中生代镁铁质岩墙群LA-ICP-MS锆石U-Pb定年、元素和Sr-Nd-Hf同位素地球化学[J].岩石学报,2011,27(11):3350-3364.
(1)长安大学和青海省有色地质八队.青海省都兰县沟里地区Ⅰ47 E003010(沟里乡)1∶5万矿产地质、水系沉积物测量综合调查成果报告. 2007.
(2)青海省地质局. 1∶20万加鲁河幅区域地质调查报告. 1973.
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