滇西南团梁子岩组分异石英脉锆石U-Pb年龄——晚三叠世澜沧江构造带区域变质变形的时代制约
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摘要
在滇西南澜沧江构造带东侧、扬子板块西缘中元古代团梁子岩组含有大量的平行于区域面理(S2)的构造热液石英脉,利用LA-ICP-MS对3件石英脉和1件绿片岩中的锆石进行~(206)U/~(238)Pb测年,获得3组明显的组合年龄:395～461Ma、240～260Ma和222～228Ma,大部分集中于222～228Ma。对比研究表明,区域上2期变质变形(M_1D_1、M_2D_2)与获得的锆石年龄有较好的对应性,早期的变质变形(M_1D_1)形成于早古生代(395～461Ma)原特提斯洋盆向东俯冲阶段;晚期的2期变质变形(M_(2a)D_(2a),M_(2b)D_(2b))发生于晚古生代—中生代早期(240～260Ma)古特提斯洋盆向东俯冲阶段和晚三叠世早期(222～228Ma)古特提斯洋盆闭合阶段。晚三叠世早期变质变形(M_(2b)D_(2b))构造热液发生在临沧花岗岩侵位和弧陆碰撞型忙怀组火山岩(229～235Ma)之后,早于小定西组/芒汇河组拉伸期火山岩(210～222Ma),是古特提斯洋与扬子陆块碰撞后的应力松弛阶段俯冲岩片快速折返的证据,同时也反映了古特提斯洋盆在晚三叠世早期之前已经关闭。
Abundant tectonic hydrothermal quartz veins were found,which are parallel to the regional foliation(S2)in Mesoproterozoic Tuanliangzi Formation in southwest Yunnan,and those ancient mixtites of Tuanliangzi Formation are important tectonic rocks in southern Lancang River tectonic belt and along the west Yangtze block.Three zircon samples of quartz dykes and one zircon sample of green dyke were selected and analyzed using laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS).The~(206)Pb/~(238)U ages can be divided into three groups,i.e.,395～461Ma,240～260Ma and 222～228Ma,with most of them concentrated on 222～228Ma.The quartz dykes ages indicate two stages of regional metamorphism deformation(M_1D_1,M_2D_2):the first stage of metamorphism deformation(M_1D_1)was the result of pro-Tethys eastward subduction in Early Paleozoic(395～461Ma);the second stage of metamorphism deformation(M_2D_2)occurred in late Paleozoic-Mesozoic which could be divided into two periods of metamorphism deformation(M_(2a)D_(2a),M_(2b)D_(2b)):the early period was Late Paleozoic to Early Mesozoic(240～260Ma)when the Paleo-Tethys experienced eastward subduction,whereas the late period of metamorphism deformation was caused by the closure of Paleo-Tethys Ocean basin in early Late Triassic(222～228Ma).The quartz dykes in Tuanliangzi Formation were impacted by tectonic hydrothermal event in the early Late Triassic,and were formed later than Lincang granite and the volcanic rocks of Manghuan Formation(229～235Ma),but earlier than stretch volcanic rocks of Xiaodingxi Formation and Manghuihe Formation(210～222Ma),which indicates that these syn-emplacement quartz dykes were the results of rapid exhumation that happened later than the Paleotethys ocean eastward collision with Yangtze block;in addition,the ancient Tethys Ocean had been closed earlier than early Late Triassic,suggesting minimum age limitation of quartz dykes in Tuanliangzi Formation.
Abundant tectonic hydrothermal quartz veins were found,which are parallel to the regional foliation(S2)in Mesoproterozoic Tuanliangzi Formation in southwest Yunnan,and those ancient mixtites of Tuanliangzi Formation are important tectonic rocks in southern Lancang River tectonic belt and along the west Yangtze block.Three zircon samples of quartz dykes and one zircon sample of green dyke were selected and analyzed using laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS).The~(206)Pb/~(238)U ages can be divided into three groups,i.e.,395～461Ma,240～260Ma and 222～228Ma,with most of them concentrated on 222～228Ma.The quartz dykes ages indicate two stages of regional metamorphism deformation(M_1D_1,M_2D_2):the first stage of metamorphism deformation(M_1D_1)was the result of pro-Tethys eastward subduction in Early Paleozoic(395～461Ma);the second stage of metamorphism deformation(M_2D_2)occurred in late Paleozoic-Mesozoic which could be divided into two periods of metamorphism deformation(M_(2a)D_(2a),M_(2b)D_(2b)):the early period was Late Paleozoic to Early Mesozoic(240～260Ma)when the Paleo-Tethys experienced eastward subduction,whereas the late period of metamorphism deformation was caused by the closure of Paleo-Tethys Ocean basin in early Late Triassic(222～228Ma).The quartz dykes in Tuanliangzi Formation were impacted by tectonic hydrothermal event in the early Late Triassic,and were formed later than Lincang granite and the volcanic rocks of Manghuan Formation(229～235Ma),but earlier than stretch volcanic rocks of Xiaodingxi Formation and Manghuihe Formation(210～222Ma),which indicates that these syn-emplacement quartz dykes were the results of rapid exhumation that happened later than the Paleotethys ocean eastward collision with Yangtze block;in addition,the ancient Tethys Ocean had been closed earlier than early Late Triassic,suggesting minimum age limitation of quartz dykes in Tuanliangzi Formation.
引文
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[4]彭头平,王岳军,范蔚茗,等.澜沧江南段早中生代酸性火成岩SHRIMP锆石U-Pb定年及构造意义[J].中国科学(D辑),200636(2):123-132.
[5]施小斌,丘学林,刘海龄,等.滇西临沧花岗岩基冷却的热年代学分析[J].岩石学报,2006,22(2):465-479.
[6]杨岳清,杨建民,徐德才,等.云南澜沧江南段火山岩演化及其铜多金属矿床的成矿特点[J].矿床地质,2006,(4):447-462.
[7]刘德利,刘继顺,张彩华,等.滇西南澜沧江结合带北段云县花岗岩的地质特征及形成环境[J].岩石矿物学杂志,2008,27(1):23-31.
[8]范蔚茗,彭头平,王岳军.滇西古特提斯俯冲-碰撞过程的岩浆作用记录[J].地学前缘,2009,16(6):291-302.
[9]陈珲,李峰,坚润堂,等.云南澜沧老厂花岗斑岩锆石SHRIMP定年及其地质意义[J].地质学报,2010,84(4):485-491.
[10]李钢柱,苏尚国,雷玮琰,等.三江地区澜沧江带南段南林山基性岩体锆石U-Pb年龄及岩石地球化学特征[J].地学前缘,201118(5):206-212.
[11]李钢柱,苏尚国,段向东.三江地区澜沧江带南段半坡杂岩体锆石U-Pb年龄、岩石地球化学特征及板块构造环境[J].地学前缘,2012,19(4):96-109.
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[13]张彩华,刘继顺,张洪培,等.滇西南澜沧带晚三叠世富钾火山岩地球化学特征及成因[J].中国有色金属学报,2012,22(3):669-679.
[14]钟维敷,冯庆来,Chongpan C,等.老挝与云南二叠纪三叠纪地层对比及其构造意义[J].地球科学(中国地质大学学报),2012(S2):73-80.
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[16]王保弟,王立全,潘桂棠,等.昌宁-孟连结合带南汀河早古生代辉长岩锆石年代学及地质意义[J].科学通报,2013,58(4):344-354.
[17]张海,金灿海,范文玉,等.云南景谷半坡铂钯多金属矿床辉长岩锆石U-Pb同位素定年及其意义[J].中国地质,2013,40(5):1433-1442.
[18]Nie X M,Feng Q L,Qian X,et al.Magmatic record of Prototethyan evolution in SW Yunnan,China:Geochemical,zircon U-Pb geochronological and Lu-Hf isotopic evidence from the Huimin metavolcanicrocks in the southern Lancangjiang zone[J].Gondwana Research,2015,28(2):757-768.
[19]Li D P,Chen Y L,Hou K J,et al.Detrital zircon record of Paleozoic and Mesozoic meta-sedimentary strata in the eastern part of the Baoshan block:Implications of their provenance and the tectonic evolution of the southeastern margin of the Tibetan plateau[J].Lithos,2015,227(15):194-204.
[20]孙载波,曾文涛,黄亮,等.滇西南团梁子岩组绿片岩、基性脉岩及构造分异石英脉岩锆石U-Pb年龄及其地质意义[J].矿物学报,2015,35(2):245-254.
[21]Hu Z C,Gao S,Liu Y S,et al.Signal enhancement in laser ablation ICP-MS by additon of nitrogen in the central channel gas[J].Journal of Analytical Atomic Spectrometry,2008,8(23):1093-1101.
[22]Liu Y S,Gao S,Hu Z C,et al..Continental and oceanic crust recycling-induced melt-peridotite interactions in the TransNorth China Orogen:U-Pb dating,Hf isotopes and trace elements in zircons of mantle xenoliths[J].Journal of Petrology,2010,51(51):392-399.
[23]Liu Y S,Hu Z C,Zong K P,et al.Reappraisement and refinement of zircon U-Pb isotope and trace element analyses by LA-ICP-MS[J].Chinese Science Bulletin,2010,55(15):1535-1546.
[24]Ludwig K R.User’s manual for Isoplot 3.00:a geochronological toolkit for microsoft Excel[M].Berkeley Geochronology Center Special Publication,2003.
[25]吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004,(16):1589-1604.
[26]Bernd L,Zhao X F,Zhou M F,et al.Mid-Silurian back-arc spreading at the northeastern margin of Gondwana:The Dapingzhang dacite-hosted massive sulfide deposit,Lancangjiang zone,southwestern Yunnan,China[J].Gondwana Research,2013,24(2):648-663.
[27]Zhao T Y,Feng Q L,Metcalfec I,et al.Detrital zircon U-Pb-Hf isotopes and provenance of Late Neoproterozoic and Early Paleozoic sediments of the Simao and Baoshan Blocks,SW China:Implications for Proto-Tethys and Paleo-Tethys evolution and Gondwana reconstruction[J].Gandwana Reaserch,2017,57:193-208.
[28]赵靖.滇西澜沧变质带中白云母的研究及其地质意义[J].岩石矿物学杂志,1993,(3):251-260.
[29]周维全,林文信.澜沧江变质带南段蓝闪石片岩特征[J].中国区域地质,1982,(2):76-85.
[30]彭兴阶,罗万林.澜沧江南段双变质带的初步确定[J].青藏高原地质文集,1983,(2):21-30.
[31]张儒瑗,从柏林,韩秀伶.滇西蓝片岩中的角闪石[J].地质科学,1990,(1):43-53.
(1)云南省地质调查院. 1∶25万临沧幅区域地质调查. 2013.
[2]赵靖,钟大赉,王毅.滇西澜沧变质带的变形序列与变质作用初步研究[J].地质科学,1994,(4):366-372.
[3]冯庆来,沈上越,刘本培,等.滇西南澜沧江构造带大新山组放射虫、硅质岩和玄武岩研究[J].中国科学(D辑),2002,32(3):220-226.
[4]彭头平,王岳军,范蔚茗,等.澜沧江南段早中生代酸性火成岩SHRIMP锆石U-Pb定年及构造意义[J].中国科学(D辑),200636(2):123-132.
[5]施小斌,丘学林,刘海龄,等.滇西临沧花岗岩基冷却的热年代学分析[J].岩石学报,2006,22(2):465-479.
[6]杨岳清,杨建民,徐德才,等.云南澜沧江南段火山岩演化及其铜多金属矿床的成矿特点[J].矿床地质,2006,(4):447-462.
[7]刘德利,刘继顺,张彩华,等.滇西南澜沧江结合带北段云县花岗岩的地质特征及形成环境[J].岩石矿物学杂志,2008,27(1):23-31.
[8]范蔚茗,彭头平,王岳军.滇西古特提斯俯冲-碰撞过程的岩浆作用记录[J].地学前缘,2009,16(6):291-302.
[9]陈珲,李峰,坚润堂,等.云南澜沧老厂花岗斑岩锆石SHRIMP定年及其地质意义[J].地质学报,2010,84(4):485-491.
[10]李钢柱,苏尚国,雷玮琰,等.三江地区澜沧江带南段南林山基性岩体锆石U-Pb年龄及岩石地球化学特征[J].地学前缘,201118(5):206-212.
[11]李钢柱,苏尚国,段向东.三江地区澜沧江带南段半坡杂岩体锆石U-Pb年龄、岩石地球化学特征及板块构造环境[J].地学前缘,2012,19(4):96-109.
[12]王硕,董国臣,莫宣学,等.澜沧江南带三叠纪火山岩岩石学、地球化学特征、Ar-Ar年代学研究及其构造意义[J].岩石学报2012,28(4):1148-1162.
[13]张彩华,刘继顺,张洪培,等.滇西南澜沧带晚三叠世富钾火山岩地球化学特征及成因[J].中国有色金属学报,2012,22(3):669-679.
[14]钟维敷,冯庆来,Chongpan C,等.老挝与云南二叠纪三叠纪地层对比及其构造意义[J].地球科学(中国地质大学学报),2012(S2):73-80.
[15]孔会磊,董国臣,莫宣学,等.滇西三江地区临沧花岗岩的岩石成因:地球化学、锆石U-Pb年代学及Hf同位素约束[J].岩石学报2012,28(5):1438-1452.
[16]王保弟,王立全,潘桂棠,等.昌宁-孟连结合带南汀河早古生代辉长岩锆石年代学及地质意义[J].科学通报,2013,58(4):344-354.
[17]张海,金灿海,范文玉,等.云南景谷半坡铂钯多金属矿床辉长岩锆石U-Pb同位素定年及其意义[J].中国地质,2013,40(5):1433-1442.
[18]Nie X M,Feng Q L,Qian X,et al.Magmatic record of Prototethyan evolution in SW Yunnan,China:Geochemical,zircon U-Pb geochronological and Lu-Hf isotopic evidence from the Huimin metavolcanicrocks in the southern Lancangjiang zone[J].Gondwana Research,2015,28(2):757-768.
[19]Li D P,Chen Y L,Hou K J,et al.Detrital zircon record of Paleozoic and Mesozoic meta-sedimentary strata in the eastern part of the Baoshan block:Implications of their provenance and the tectonic evolution of the southeastern margin of the Tibetan plateau[J].Lithos,2015,227(15):194-204.
[20]孙载波,曾文涛,黄亮,等.滇西南团梁子岩组绿片岩、基性脉岩及构造分异石英脉岩锆石U-Pb年龄及其地质意义[J].矿物学报,2015,35(2):245-254.
[21]Hu Z C,Gao S,Liu Y S,et al.Signal enhancement in laser ablation ICP-MS by additon of nitrogen in the central channel gas[J].Journal of Analytical Atomic Spectrometry,2008,8(23):1093-1101.
[22]Liu Y S,Gao S,Hu Z C,et al..Continental and oceanic crust recycling-induced melt-peridotite interactions in the TransNorth China Orogen:U-Pb dating,Hf isotopes and trace elements in zircons of mantle xenoliths[J].Journal of Petrology,2010,51(51):392-399.
[23]Liu Y S,Hu Z C,Zong K P,et al.Reappraisement and refinement of zircon U-Pb isotope and trace element analyses by LA-ICP-MS[J].Chinese Science Bulletin,2010,55(15):1535-1546.
[24]Ludwig K R.User’s manual for Isoplot 3.00:a geochronological toolkit for microsoft Excel[M].Berkeley Geochronology Center Special Publication,2003.
[25]吴元保,郑永飞.锆石成因矿物学研究及其对U-Pb年龄解释的制约[J].科学通报,2004,(16):1589-1604.
[26]Bernd L,Zhao X F,Zhou M F,et al.Mid-Silurian back-arc spreading at the northeastern margin of Gondwana:The Dapingzhang dacite-hosted massive sulfide deposit,Lancangjiang zone,southwestern Yunnan,China[J].Gondwana Research,2013,24(2):648-663.
[27]Zhao T Y,Feng Q L,Metcalfec I,et al.Detrital zircon U-Pb-Hf isotopes and provenance of Late Neoproterozoic and Early Paleozoic sediments of the Simao and Baoshan Blocks,SW China:Implications for Proto-Tethys and Paleo-Tethys evolution and Gondwana reconstruction[J].Gandwana Reaserch,2017,57:193-208.
[28]赵靖.滇西澜沧变质带中白云母的研究及其地质意义[J].岩石矿物学杂志,1993,(3):251-260.
[29]周维全,林文信.澜沧江变质带南段蓝闪石片岩特征[J].中国区域地质,1982,(2):76-85.
[30]彭兴阶,罗万林.澜沧江南段双变质带的初步确定[J].青藏高原地质文集,1983,(2):21-30.
[31]张儒瑗,从柏林,韩秀伶.滇西蓝片岩中的角闪石[J].地质科学,1990,(1):43-53.
(1)云南省地质调查院. 1∶25万临沧幅区域地质调查. 2013.
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