内蒙古格勒敖包奥陶纪岩体锆石U-Pb年龄及地球化学特征
|
摘要
内蒙古格勒敖包位于兴蒙造山带内,对该区奥陶纪岩浆岩的研究,有助于进一步认识该造山带早古生代的构造格局及其演化。正长花岗岩和斑状二长花岗岩样品LA-ICP-MS锆石年龄为441.6±3.7～454.9±4.6Ma,形成时代为奥陶纪。经地球化学分析,岩体为高钾钙碱性系列;铝饱和指数显示其为过铝质花岗岩。岩石富集大离子亲石元素(LILEs)Rb、Th、U、K,亏损Ba、Sr;富集高场强元素(HFSEs)La、Ce、Nd、Zr,亏损Nb、P、Ti;稀土元素总量为38.7×10~(-6)～120.23×10~(-6),轻稀土元素较重稀土元素分异明显,分馏程度较高,表现出较弱的负Eu异常。综合区域地质资料,认为格勒敖包奥陶纪岩浆源区为上地壳物质的部分熔融,其形成环境为弧后盆地,在古亚洲洋向北俯冲之后经历了岛弧岩浆作用旋回,为弧后伸张阶段的产物。
The Geleaobao area of Inner Mongolia is located in the Xingmeng orogenic belt. By studying the Ordovician magmatic rocks in this area, researchers can further understand the structure and evolution of the Early Paleozoic strata in this orogenic belt.The ages of the LA-ICP-MS zircons of syenite and mottled monzogranite samples studied in this work are 441.6±3.7 Ma to 454.9±4.6 Ma. The age of formation is Ordovician. Geochemical analysis shows that the pluton has high-K calc-alkaline characteristics.Aluminum saturation index shows that it is peraluminous granite. The characteristics of trace elements in rocks indicate that they are enriched in large ionic lithophilic elements(LILEs) Rb, Th, U, K, depleted in Ba, Sr; enriched in high field strength elements(HFSEs) La, Ce, Nd, Zr, and depleted in Nb, P, Ti. The total amount of rare earths in the rocks is 38.7×10~(-6) to 120.23×10~(-6), and the light rare earths exhibit obvious differences in heavier rare earths, with higher fractionation and weaker negative Eu anomalies.Based on regional geological data, it is believed that the source region of the Ordovician magma in the Geleaobao area is partially melted upper crustal materials, and the formation environment was a back-arc basin. After the subduction of the ancient Asian Ocean to the north, it experienced an island-arc magmatic process cycle, being product of extension stage.
The Geleaobao area of Inner Mongolia is located in the Xingmeng orogenic belt. By studying the Ordovician magmatic rocks in this area, researchers can further understand the structure and evolution of the Early Paleozoic strata in this orogenic belt.The ages of the LA-ICP-MS zircons of syenite and mottled monzogranite samples studied in this work are 441.6±3.7 Ma to 454.9±4.6 Ma. The age of formation is Ordovician. Geochemical analysis shows that the pluton has high-K calc-alkaline characteristics.Aluminum saturation index shows that it is peraluminous granite. The characteristics of trace elements in rocks indicate that they are enriched in large ionic lithophilic elements(LILEs) Rb, Th, U, K, depleted in Ba, Sr; enriched in high field strength elements(HFSEs) La, Ce, Nd, Zr, and depleted in Nb, P, Ti. The total amount of rare earths in the rocks is 38.7×10~(-6) to 120.23×10~(-6), and the light rare earths exhibit obvious differences in heavier rare earths, with higher fractionation and weaker negative Eu anomalies.Based on regional geological data, it is believed that the source region of the Ordovician magma in the Geleaobao area is partially melted upper crustal materials, and the formation environment was a back-arc basin. After the subduction of the ancient Asian Ocean to the north, it experienced an island-arc magmatic process cycle, being product of extension stage.
引文
[1]刘家义.内蒙贺根山地区蛇绿岩套研究及构造意义[C]//中国地质科学院文集(1982中英文合订本),1985:2.
[2]王树庆,许继峰,刘希军,等.内蒙朝克山蛇绿岩地球化学:洋内弧后盆地的产物?[J].岩石学报,2008,24(12):2869-2879.
[3]黄波,付冬,李树才,等.内蒙古贺根山蛇绿岩形成时代及构造启示[J].岩石学报,2016,32(1):158-176.
[4]徐备,赵盼,鲍庆中,等.兴蒙造山带前中生代构造单元划分初探[J].岩石学报,2014,30(7):1841-1857.
[5]Xiao W J,Windley B F,Hao J,et al.Accretion leading to collision and the Permian Solonker Suture,Inner Mongolia,China:Termination of the Central Asian Orogenic Belt[J].Tectonics,2003,22(6):1069-1090.
[6]Li J Y.Permian Geodynamic Setting of Northeast China and Adjacent regions:Closure of the Paleo-Asian Ocean and dubduction of the Paleo-Pacific Plate[J].Journal of Asian Earth Sciences,2006,26(3/4):207-224.
[7]Jian P,Liu D Y,Kr?ner A,et al.Time scale of the early to midPaleozoic orogenic cycle of the longlived Central Asian Orogenic Belt,Inner Mongolia of China:implications for continental growth[J].Lithos,2008,101(3/4):233-259.
[8]Xu B,Charvet J,Chen Y,et al.Middle Paleozoic convergent orogenic belts in western Inner Mongolia(China):framework,kinematics,geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[J].Gondwana Research,2013,23(4):1342-1364.
[9]杨泽黎,王树庆,胡晓佳,等.内蒙古吉尔嘎郎图早古生代岩体成因--年代学、地球化学及Nd-Hf同位素制约[J].地质通报,2017,36(8):1369-1384.
[10]赵利刚,冉皞,张庆红,等.内蒙古阿巴嘎旗奥陶纪岩体的发现及地质意义[J].世界地质,2012,31(3):451-461.
[11]李红英,周志广,李鹏举,等.内蒙古东乌珠穆沁旗晚奥陶世辉长岩地球化学特征及其地质意义[J].地质论评,2016,62(2):300-316.
[12]Hoskin P W O,Black L P.Metamorphic zircon formation by solidstate recrystallization of protolith igneous ziron[J].Metamorphic Geol.,2000,18:423-439.
[13]Hoskin P W O,Schaltegger U.The composition of zircon and igneous and metamorphic petrogenesis[J].Reviews in Mineralogy and Geochemistry,2003,53:27-62.
[14]Corfu F,Hanchar J M,Hoskin P W O,et al.Atlas of zircon textures[J].Reviews in Mineralogy and Geochemistry,2003,53(1):469-500.
[15]Middlemost E A K.Naming materials in the magma/igneous rock system[J].Earth Science Reviews,1994,37(3/4):215-224.
[16]Wright J B.A simple alkalinity ratio and its application to questions of nonorogenic granite genesis[J].Geological Magazine,1969,106(4):370-384.
[17]Peccerillo R,Taylor S R.Geochemistry of eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contrib.Mineral.Petrol.,1976,58:63-81.
[18]Maniar P D,Piccoli P M.Tectonic discrimination of granitoids[J].Geological Society of America Bulletin,1989,101(5):635-643.
[19]Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society of London Special Publications,1989,42(1):313-345.
[20]Bowden P.The geochemistry and mineralization of alkaline ring complexes in Africa(a review)[J].Journal of African Earth Sciences,1985,3(1/2):17-39.
[21]Eby G N.Chemical subdivision of the A-type granitoids:Petrogenetic and tectonic implications[J].Geology,1992,20:641-644.
[22]张磊,吕新彪,刘阁,等.兴蒙造山带东段大陆弧后A型花岗岩特征与成因[J].中国地质,2013,40(3):869-884.
[23]Eby G N,王宾.A型花岗岩类的化学分类:岩石成因和构造意义[J].国外火山地质,1994,(1):38-42.
[24]Batchelor R A,Bowden P.Petrogenetic interpretation of granitoid rock seriesusing multicationic parameters[J].Chem.Geol.,1985(48):43-55.
[25]潘桂棠,陆松年,肖庆辉,等.中国大地构造阶段划分和演化[J].地学前缘,2016,23(6):1-23.
[26]Harris N B W,Pearce J A,Tindle A G.Geochemical characteristics of collision-zone magmatism[C]//Coward M P,Reis A C.Collision tectonics.Spec.Publ.Grol.Soc.Lond.,1986,19:67-81.(1).15
(1)内蒙古自治区地质调查院.内蒙古1∶5万阿格廷查干陶乐盖等六幅区域矿产地质调查报告. 2018.
[2]王树庆,许继峰,刘希军,等.内蒙朝克山蛇绿岩地球化学:洋内弧后盆地的产物?[J].岩石学报,2008,24(12):2869-2879.
[3]黄波,付冬,李树才,等.内蒙古贺根山蛇绿岩形成时代及构造启示[J].岩石学报,2016,32(1):158-176.
[4]徐备,赵盼,鲍庆中,等.兴蒙造山带前中生代构造单元划分初探[J].岩石学报,2014,30(7):1841-1857.
[5]Xiao W J,Windley B F,Hao J,et al.Accretion leading to collision and the Permian Solonker Suture,Inner Mongolia,China:Termination of the Central Asian Orogenic Belt[J].Tectonics,2003,22(6):1069-1090.
[6]Li J Y.Permian Geodynamic Setting of Northeast China and Adjacent regions:Closure of the Paleo-Asian Ocean and dubduction of the Paleo-Pacific Plate[J].Journal of Asian Earth Sciences,2006,26(3/4):207-224.
[7]Jian P,Liu D Y,Kr?ner A,et al.Time scale of the early to midPaleozoic orogenic cycle of the longlived Central Asian Orogenic Belt,Inner Mongolia of China:implications for continental growth[J].Lithos,2008,101(3/4):233-259.
[8]Xu B,Charvet J,Chen Y,et al.Middle Paleozoic convergent orogenic belts in western Inner Mongolia(China):framework,kinematics,geochronology and implications for tectonic evolution of the Central Asian Orogenic Belt[J].Gondwana Research,2013,23(4):1342-1364.
[9]杨泽黎,王树庆,胡晓佳,等.内蒙古吉尔嘎郎图早古生代岩体成因--年代学、地球化学及Nd-Hf同位素制约[J].地质通报,2017,36(8):1369-1384.
[10]赵利刚,冉皞,张庆红,等.内蒙古阿巴嘎旗奥陶纪岩体的发现及地质意义[J].世界地质,2012,31(3):451-461.
[11]李红英,周志广,李鹏举,等.内蒙古东乌珠穆沁旗晚奥陶世辉长岩地球化学特征及其地质意义[J].地质论评,2016,62(2):300-316.
[12]Hoskin P W O,Black L P.Metamorphic zircon formation by solidstate recrystallization of protolith igneous ziron[J].Metamorphic Geol.,2000,18:423-439.
[13]Hoskin P W O,Schaltegger U.The composition of zircon and igneous and metamorphic petrogenesis[J].Reviews in Mineralogy and Geochemistry,2003,53:27-62.
[14]Corfu F,Hanchar J M,Hoskin P W O,et al.Atlas of zircon textures[J].Reviews in Mineralogy and Geochemistry,2003,53(1):469-500.
[15]Middlemost E A K.Naming materials in the magma/igneous rock system[J].Earth Science Reviews,1994,37(3/4):215-224.
[16]Wright J B.A simple alkalinity ratio and its application to questions of nonorogenic granite genesis[J].Geological Magazine,1969,106(4):370-384.
[17]Peccerillo R,Taylor S R.Geochemistry of eocene calc-alkaline volcanic rocks from the Kastamonu area,Northern Turkey[J].Contrib.Mineral.Petrol.,1976,58:63-81.
[18]Maniar P D,Piccoli P M.Tectonic discrimination of granitoids[J].Geological Society of America Bulletin,1989,101(5):635-643.
[19]Sun S S,Mcdonough W F.Chemical and isotopic systematics of oceanic basalts:Implications for mantle composition and processes[J].Geological Society of London Special Publications,1989,42(1):313-345.
[20]Bowden P.The geochemistry and mineralization of alkaline ring complexes in Africa(a review)[J].Journal of African Earth Sciences,1985,3(1/2):17-39.
[21]Eby G N.Chemical subdivision of the A-type granitoids:Petrogenetic and tectonic implications[J].Geology,1992,20:641-644.
[22]张磊,吕新彪,刘阁,等.兴蒙造山带东段大陆弧后A型花岗岩特征与成因[J].中国地质,2013,40(3):869-884.
[23]Eby G N,王宾.A型花岗岩类的化学分类:岩石成因和构造意义[J].国外火山地质,1994,(1):38-42.
[24]Batchelor R A,Bowden P.Petrogenetic interpretation of granitoid rock seriesusing multicationic parameters[J].Chem.Geol.,1985(48):43-55.
[25]潘桂棠,陆松年,肖庆辉,等.中国大地构造阶段划分和演化[J].地学前缘,2016,23(6):1-23.
[26]Harris N B W,Pearce J A,Tindle A G.Geochemical characteristics of collision-zone magmatism[C]//Coward M P,Reis A C.Collision tectonics.Spec.Publ.Grol.Soc.Lond.,1986,19:67-81.(1).15
(1)内蒙古自治区地质调查院.内蒙古1∶5万阿格廷查干陶乐盖等六幅区域矿产地质调查报告. 2018.
© 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 |