胶-辽-吉造山带东部古元古代构造活动新记录:来自吉林省大兴铁矿区变辉长岩-碳酸岩杂岩的启示  

New record of Paleoproterozoic tectonic activity in eastern Jiao-Liao-Ji Orogenic Belt:implications from metamorphic gabbro-carbonatite complex in Daxing iron mining area,Jilin Province

作　　者：臧兴运[1,2] 吕鹏 王聚胜[1,2] 李斌[1,2] 闫冬 孙伟国[1] 李翱鹏[1] 王永胜 ZANG Xingyun;L Peng;WANG Jusheng;LI Bin;YAN Dong;SUN Weiguo;LI Aopeng;WANG Yongsheng(Geological Survey Institute of Jilin Province,Changchun 130102,China;Northeast Geological Science&Technology Innovation Center,China Geological Survey,Shenyang 110034,China)

机构地区：[1]吉林省地质调查院,长春130102 [2]中国地质调查局东北地质科技创新中心,沈阳110034

出　　处：《世界地质》2025年第1期1-21,共21页World Geology

基　　金：中国地质调查局东北地质科技创新中心区创基金项目(QCJJ2022-20)。

摘　　要：为制约胶-辽-吉造山带东部的构造演化,笔者利用岩石学、岩石化学、岩石地球化学、锆石U-Pb定年对大兴铁矿区变辉长岩-碳酸岩杂岩的岩石成因、成岩构造背景展开研究。结果显示,大兴铁矿区变辉长岩-碳酸岩杂岩岩石类型有变辉长岩、碳酸岩、磁铁矿体,以变辉长岩为主。岩石化学研究表明,变辉长岩w(SiO_(2))在44.23%~48.80%之间,w(Na_(2)O)在0.94%~2.86%之间,w(K_(2)O)在0.51%~1.90%之间,w(TiO_(2))在0.42%~0.93%之间,w(CaO)在8.73%~14.78%之间,Na_(2)O/K_(2)O在1.12~2.27之间,MgO/(FeO+MgO)的比值介于0.54~0.60之间,(Mg^(2+)+Ni^(2+))/(Fe^(2+)+Fe^(3+)+Mn^(2+))为1.44~2.02,Mg/(Mg+Fe^(2+))为0.60~0.68,分异指数(DI)介于11.76~31.79,岩石呈现偏碱性的富铁、钠,低钾、钛的基性-超基性岩浆特征,分异作用较弱。岩石地球化学研究表明,富集Rb、Ba等大离子亲石元素[w(Rb)(4.80×10^(-6)~74.82×10^(-6)),w(Ba)(83.09×10^(-6)~430.10×10^(-6))],高场强元素Hf、Th、Ta等相对较为富集[w(Hf)(1.41×10^(-6)~6.20×10^(-6))、w(Th)(0.51×10^(-6)~28.91×10^(-6))、w(Ta)(0.47×10^(-6)~9.91×10-6)],∑REE=(29.56×10^(-6)~812.59×10^(-6)),Nb元素明显亏损[w(Nb)(2.94×10^(-6)~36.01×10^(-6))];(Na_(2)O+K_(2)O)/TiO_(2)比值为0.10~5.54,Zr/Y比值为1.93~5.67,La/Nb比值为0.54~1.73,La/Ta比值为5.53~11.13,Nb/U比值为1.51~14.23,地球化学特征类似于大陆拉斑玄武岩,同时具有板内碱性玄武岩性质。碳酸岩与变辉长岩互层出现,CaO/(CaO+MgO+Fe_(2)O_(3)+FeO+MnO)均值为0.98,w(MgO)均值为0.62,w(FeO+Fe_(2)O_(3)+MnO)均值为0.41,为钙质偏镁质碳酸岩,明显富集Sr元素[w(Sr)(1727×10^(-6)~1794×10^(-6))]。杂岩体岩浆可能来自软流圈富集地幔的部分熔融,形成于大陆板内深大断裂带拉张的构造背景,并在上升过程中与地壳物质发生一定程度的同化混染作用。变辉长岩的锆石绝大多数具有核边结构,其核部色泽大多呈黑色,难以观察其内部结构,少数核部可见较宽的振荡�In order to constrain the tectonic evolution of the eastern part of the Jiao-Liao-Ji Orogenic Belt,the authors carried out a study on the petrogenesis and diagenetic tectonic background of the metamorphic gabbro-carbonatite complex in the Daxing iron mining area by using petrology,petrochemistry,petrogeochemistry and zircon U-Pb dating.The results show that the metamorphic gabbro-carbonatite complex in the Daxing iron mining area has the rock types of meta-gabbro,carbonatite and magnet ore body,and the mata-gabbro is the main rock type.Petrochemical study of the meta-gabbro showed that the w(SiO_(2))is from 44.23%to 48.80%,w(Na_(2)O)is from 0.94%to 2.86%,w(K_(2)O)is from 0.51%to 1.90%,w(TiO_(2))is from 0.42%to 0.93%,w(CaO)is from 8.73%to 14.78%,and the Na_(2)O/K_(2)O ratio ranges from 1.12 to 2.27,MgO/(FeO+MgO)ratio ranges from 0.54 to 0.60,(Mg^(2+)+Ni^(2+))/(Fe^(2+)+Fe^(3+)+Mn^(2+))ratio ranges from 1.44 to 2.02,Mg/(Mg+Fe^(2+))ratio ranges from 0.60 to 0.68,and the differentiation index(DI)ranges from 11.76 to 31.79.The meta-gabbro rocks are basic-ultrabasic magma which is rich in iron and sodium,poor in potassium and titanium,and weak in differentiation.Geochemical studies show that the rocks are rich in large ion lithophile elements such as Rb,Ba[w(Rb)(4.80×10^(-6)-74.82×10^(-6)),w(Ba)(83.09×10^(-6)-430.10×10^(-6))],and relatively rich in high field strength elements such as Hf,Th,Ta[w(Hf)(1.41×10^(-6)-6.20×10^(-6)),w(Th)(0.51×10^(-6)-28.91×10^(-6)),w(Ta)(0.47×10^(-6)-9.91×10^(-6))],and∑REE=(29.56×10^(-6)-812.59×10^(-6));while,Nb is obviously depleted[w(Nb)(2.94×10^(-6)-36.01×10^(-6))].The(Na_(2)O+K_(2)O)/TiO_(2) ratio is 0.10-5.54,Zr/Y ratio is 1.93-5.67,La/Nb ratio is 0.54-1.73,La/Ta ratio is 5.53-11.13,Nb/U ratio is 1.51-14.23.The geochemical characteristics are similar to continental tholeiitic basalts,and having the properties of intra-plate alkaline basalts.The carbonatite and meta-gabbro are interbedded.The average CaO/(CaO+MgO+Fe_(2)O_(3)+FeO+MnO)ratio is 0.98,mean w(MgO)is 0.62,and mea

关 键 词：变辉长岩 碳酸岩 古元古代 大兴铁矿区 胶-辽-吉造山带 吉林省 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]