摘要
位于中亚造山带东段的中国东北地区由众多微地块拼合而成,但各地块间的拼贴时间、位置和演化过程一直是地学界争议的关键科学问题.针对大兴安岭中段蘑菇气地区晚石炭世-早二叠世宝力高庙组砂岩开展了详细的岩相学、碎屑锆石LA-ICP-MS U-Pb年代学研究,分析了砂岩母岩区大地构造背景,进而约束兴安地块与松辽地块的汇聚过程.研究结果表明,砂岩具有成分成熟度低、近源快速沉积特点,碎屑骨架成分显示了火成岩区物源供给.锆石颗粒CL图像、Th/U值及REE特征均指示了锆石为岩浆成因.测试样品中锆石U-Pb年龄主要集中在282~360Ma(n=134),峰值年龄约为290Ma、305Ma、325Ma和350Ma.结合区域内前人的研究成果,暗示了其物源可能来自蘑菇气-嫩江-黑河一线的晚古生代俯冲-同碰撞期岩浆弧;样品中最年轻的锆石U-Pb年龄分别为282±4Ma(样品15MG10)和287±4Ma(样品15MG11),可以限定砂岩的沉积下限为早二叠世.对比索伦-蘑菇气地区晚石炭世-早三叠世砂岩的碎屑锆石年龄组成,发现兴安地块内晚石炭世-早二叠世碎屑组分与松辽地块内中二叠世-早三叠世碎屑组分基本相同,说明兴安地块与松辽地块已于晚石炭世前沿贺根山-黑河缝合带完成拼合.
Northeast China,located in the eastern part of the Central Asian orogenic belt（CAOB）,is composed of several micro-blocks（e.g.Erguna block,Xing＇an block,Songliao block and Jiamusi block）.However the suturing locations,timing and the amalgamation processes among the micro-blocks are still unclear.This study focuses on the systematic study on petrography and detrital zircon LA-ICP-MS U-Pb ages of the Late Carboniferous to Early Permian sandstones from the BaoligaomiaoFormation in the Moguqi area,Central Great Xing＇an range,in order to reveal the tectonic background of the provenances and constrain the evolution history of the Xing＇an and Songliao blocks.Petrographically,detrital compositions show that the investigated sandstones are immature,probably due to rapid erosion,transportation,and diagenetic processes,as well as nearly supplying from the source area.Additionally,the abundance of volcanic lithic reveals that the magmatic provenance dominates.Meanwhile,the cathodoluminescence（CL）images,Th/U ratios and REE pattern of analyzed zircons also imply the igneous origin.Zircon U-Pb ages obtained from the analyzed samples are mainly concentrated in 282-360 Ma（n=134）,with the peaks at ca.290 Ma,305 Ma,325 Ma and 350 Ma.By combining our new geochronological data with previous regional reports,it is concluded that the provenance of the sandstones is possibly derived from the subduction-and syn-collision-related Paleozoic magmatic arc along the Moguqi-Nenjiang-Heihe areas.Furthermore,the youngest zircon U-Pb ages of 282±4 Ma（sample15 MG10）and 287±4 Ma（sample 15 MG11）give the lower limit age of sediments.Comparing the detrital zircon U-Pb concentrations of the Late Carboniferous to Early Triassic sandstones in the Suolun-Moguqi areas,it is found that there is no difference between the Late Carboniferous to Early Permian clastic components in the Xing＇an block and the Middle Permian to Early Triassic ones in the Songliao block,indicating the above mentioned two blocks have been amalgamated
作者
赵英利
刘永江
李伟民
冯志强
温泉波
梁琛岳
Zhao Yingli;Liu Yongjiang;Li Weimin;Feng Zhiqiang;Wen Quanbo;Liang Chenyue(Research Center of Paleontology ＆ Stratigraphy, Jilin University, Changchun 130026, China;College of Earth Sciences, Jilin University, Changchun 130061, China;Key Laboratory of Mineral Resources Evaluation in Northeast Asia, Ministry of Land and Resources, Changchun 130061, China;Department of Earth Science and Engineering, Taiyuan University Of Technology, Taiyuan 030024, China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2018年第6期2055-2075,共21页
Earth Science
基金
国家"973"项目(No.2013CB429802)
青年基金项目(Nos.41502207
41602235
41302175)
