闽西南广平推覆构造变形样式与年代学约束及动力学意义  

Deformation style and geochronological constraints of Guangping nappe structure in southwest Fujian and its geodynamic significance

作　　者：吕良冀[1] 张达[1] 林全胜[1,2] 王森[1] 张旭[1] 狄永军[1] 袁远[1] 

机构地区：[1]中国地质大学(北京)地质过程与矿产资源国家重点实验室,北京100083 [2]福建省闽西地质大队,福建三明365001

出　　处：《中南大学学报（自然科学版）》2014年第3期862-875,共14页Journal of Central South University:Science and Technology

基　　金：中国地质调查局地质调查项目(1212011085472;1212010813064;1212010533105);高等学校学科创新引智计划项目(B07011)

摘　　要：为探求闽西南广平推覆构造的变形特征和形成时代，对闽西南广平推覆构造原地及外来岩系进行构造解析，对卷入推覆构造带的花岗斑岩脉采用LA-ICPMS锆石U-Pb测年方法进行测试。研究结果表明：广平推覆体中外来岩系和原地岩系表现为不同类型的褶皱及断裂等构造变形特征，其中外来岩系总体上为叠瓦式、背形堆垛式等双重逆冲推覆构造样式，而原地岩系则主要为大型倒转向斜，表现为闽西南推覆构造前锋带强烈构造变形特征；卷入推覆构造带的花岗斑岩年龄为（142＋1）Ma。结合区域资料得出结论：广平推覆构造主构造开始于早侏罗世末期（183～190．4Ma），结束于（142±1）Ma。广平推覆构造强烈构造变形样式及年代学特征表明：中国东南部中生代广泛发育的推覆构造可能和晚侏罗世一早白垩世伊佐奈崎板块与欧亚板块的强烈作用密切相关。To seek the deformation characteristic and the age of Guangping nappe structure, we made structural analysis for its autochthone and allochthone, and made dating for the granitic porphyry in the thrust by LA-ICPMS zircon U-Pb dating. The results indicate that the autochthone and the allochthone show quite different types of structural deformation such as folds and faults. The allochthone of Guangping nappe structure shows duplex thrust such as imbricate fan and antiformal stack duplex as a whole, whereas the autochthone forms large inverted syncline, which characterizes intense formation in the nappe front in Southwest Fujian. The age of the granitic porphyry in the thrust belt is about （142±1） Ma. Along with the other data of this area, we can make a conclusion that Guangping nappe structure happened in late Early Jurassic （183 Ma to 190.4 Ma） and ended at around （142±1） Ma. The intense tectonic deformation and geochronological significance of Guangping nappe structure indicate the possible close relationship between widespread Mesozoic thrust in Southeast China and the strong interaction between Izanagi Plate and Eurasia Plate from Late Jurassic to Early Cretaceous.

关 键 词：闽西南 广平推覆构造 构造变形样式 花岗斑岩 LA-ICPMS锆石U-Pb年龄 

分 类 号：P548[天文地球—构造地质学]