南秦岭佛坪地区早中生代变质-深熔-变形作用的锆石U-Pb年代学制约 |
|
关键词:metamorphism-anataxis-deformation U-Pb dating gneiss dome strike-slip shear zone South Qinling belt |
基金项目:国家重点基础研究发展规划项目(编号: 2015CB856104);国家自然科学基金项目(编号: 41872059; 41472064) |
|
摘要点击次数: 3533 |
全文下载次数: 1508 |
摘要: |
Early Mesozoic Metamorphism, Anataxis and Deformation of Foping Area in South Qinling Belt: Constrains from U-Pb Zircon Dating |
In this study, Based on an analysis of geometry and kinematics, the authors outlined a framework of Longcaoping migmatitic gneiss dome, Foping County gneiss dome and Yangtianba-Shilipu strike-slip shear zone. This paper also presents a combined petrologic and geochronologic study of migmatites, granulites and deformed granitoids from Foping area in South Qinling belt. Zircons from migmatite show distinct core-rim structure. The mesosome of migmatite yielded a weighted mean age of (211.8±9) Ma, while the leucosome contains Late Triassic zircon rims with U-Pb age of (203.7±1.6) Ma and detrital zircon cores with age spectrum analogous to that of the Devonian metasedimentary rocks from Foping area. Zircons from granulite also show distinct core-rim structure, with U-Pb age of (201.5±7.0) Ma for the core and (188.1±1.5) Ma for the rim. The pegmatite and granite dikes recorded similar ages at (200.4±2.0) Ma and (201.1±1.5) Ma, while two gneisses yielded slightly younger ages at (198.1±2.2) Ma and (196.1±2.1) Ma. The deformed granite yielded a weighted mean age of (205.5±3.0) Ma. Combining the tectonic analysis with the study of metamorphism, anataxis and magmatism, the authors constructed an Early Mesozoic tectonic evolution sequence and put forward the opinion that the activation of the Yangtianba–Shilipu strike-slip shear zone facilitated the emplacement of gneiss domes. It is also held that the South Qinling belt was under a subduction setting prior to 217~212 Ma, collision setting in 211~201 Ma and post-collision setting during 200~190 Ma. |
LIU Zhi-hui,CHEN Long-yao,QU Wei,HU Juan,LIU Xiao-chun.2019.Early Mesozoic Metamorphism, Anataxis and Deformation of Foping Area in South Qinling Belt: Constrains from U-Pb Zircon Dating[J].Acta Geoscientica Sinica,40(4):545-562. |
查看全文 查看/发表评论 下载PDF阅读器 |
|
|
|
|
|