大别山东北缘构造片麻岩中锆石U-Pb年代学分析及构造意义  

The zircon U-Pb chronology analysis of the tectonic gneiss in the northeastern Dabieshan and its tectonic significance

作　　者：李海龙 宋传中[2] 李加好[2] 任升莲[2] 王微[1,3] 李振伟 袁芳[2] Li Hailong;Song Chuanzhong;Li Jiahao;Ren Shenglian;Wang Wei;Li Zhenwei;Yuanfang(Key Laboratory of Nuclear Resources and Environment, East China University of Technology, Nanchang 330013;School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009;School of Earth Sciences, East China University of Technology, Nanchang 330013)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,南昌330013 [2]合肥工业大学资源与环境工程学院,合肥230009 [3]东华理工大学地球科学学院,南昌330013

出　　处：《地质科学》2019年第3期796-817,共22页Chinese Journal of Geology(Scientia Geologica Sinica)

基　　金：国家自然科学基金项目(编号:41272222);东华理工大学核资源与环境国家重点实验室开放基金项目(编号:NRE1806)资助。

摘　　要：大别造山带是由华北板块和扬子板块经过长期构造演化、最终碰撞拼合的产物。大别山东北缘发育地壳深部构造层次上的构造片麻岩,通过对构造片麻岩的应力场恢复,认为大别山东北缘主要受到NE-SW向的特提斯构造体制和NW-SE向的太平洋构造体制两个体制的作用,并不是受单一的构造体制控制。锆石LA-ICP-MS微区U-Pb同位素测年结果显示,大别山东北缘至少存在3期构造事件。第一期是750±50 Ma的岩浆活动;第二期是210±10 Ma的变质活动;第三期是130±5 Ma的岩浆活动。大别山在碰撞造山后期发生了近水平东西向沿造山带的塑形流变,导致大别山中片麻理和线理走向均为NWW-SEE向,大别造山带发生塑形流变的时间在210±10 Ma左右,大概在195±5 Ma左右郯庐断裂带开始活动,改造了大别山原有的NWW-SEE向构造,使得大别山东端片麻理走向出现NE向转变。The Dabie orogenic belt was the product of the long-term tectonic evolution and final collision between the North China plate and the Yangtze plate. The tectonic gneiss on the deep tectonic level of the crust developed in the northeastern Dabieshan. By restoring the stress field of the tectonic gneiss, it was considered that the northeastern Dabieshan was mainly affected by the two systems of NE-SW oriented Tethys tectonic system and NW-SE oriented Pacific tectonic system, rather than controlled by a single tectonic system. U-Pb isotopic dating of zircon LA-ICP-MS showed that there were at least three stages of tectonic events in the northeastern Dabieshan. The first stage was the magmatic activity at about 750±50 Ma, the second stage was the metamorphic activity at around 210±10 Ma and the third stage was the magmatic activity at about 130±5 Ma. The nearly horizontal E-W plastic rheology along the Dabieshan occurred in the late collision orogeny lead to the NWW-SEE direction of the gneissic schistosity and lineation in the Dabieshan. The time of the plastic rheology of the Dabie orogenic belt was about 210±10 Ma, and the Tan-Lu fault zone began at about 195±5 Ma, which reformed the original NWW-SEE direction structure of the Dabieshan, making the gneissic schistosity trend in the northeastern Dabieshan transformed toward NE direction change.

关 键 词：大别造山带 构造片麻岩 塑性流变 构造转换 

分 类 号：P542[天文地球—构造地质学] P597.3[天文地球—地质学]