地质论评2018，Vol.64Issue(3)：551-568,18.DOI:10.16509/j.georeview.2018.03.003
肥东杂岩的锆石U-Pb年龄及其地质意义——兼论下扬子地区新元古代岩浆活动历史
Zircon U-Pb Ages and Their Geological Significance of the Feidong Complex:Some Comments on Neoproterozoic Magmatism History in the Lower Yangtze Region
摘要
Abstract
Objectives:Discovery of many Neoproterozoic igneous rocks in the Lower Yangtze region provides windows for understanding Neoproterozoic magmatism history and features in the Yangtze Plate. Methods:We used the LA-ICP-MS zircon U-Pb method to date two gneiss samples from the Feidong Complex in the Lower Yangtze region. This and previous zircon U-Pb dating results from the Lower Yangtze region were analyzed for understanding the Neoproterozoic magmatic history in the region. Zircon age spectra for the Lower Yangtze region and other areas of the Yangtze Plate were then correlated for interpreting the magmatic events and their tectonic setting. Results: Zircon U-Pb dating for two orthogneiss samples from the Feidong Complex in the southern Zhangbaling Uplift gave protolith age of 805 ± 9 Ma and 804 ± 10 Ma(Neoproterozoic). This and previous zircon dating data demonstrate that protolith ages of meta-igneous rocks in the Zhangbaling Group, Feidong Complex and Dongling Complex are 767~748 Ma, 812~745 Ma and 829~754 Ma respectively. The protolith ages of meta-volcanic rocks in the Zhangbaling Group show a peak at 750 Ma whereas those of meta-igneous rocks in the Feidong Complex exhibit clusters at 800 Ma and 750 Ma. The protolith ages of meta-volcanic rocks in the Dongling Complex are 761~754 Ma whereas those of the meta-plutons are 829~812 Ma with a peak at 825 Ma. The Neoproterozoic igneous rocks resulted from three phases of magmatism with peak ages of 750 Ma, 800 Ma and 825 Ma. The magmatism with the peak age of 825 Ma occurred only in the southern Lower Yangtze region next to the Jiangnan Orogen. Ages of captured,inherited and detrital zircons from the Neoproterozoic rocks suggest other three phases of magmatism with peak ages of 840 Ma,2010 Ma and 2454 Ma and the absence of 1000 Ma~860 Ma magmatism in the Lower Yangtze region. Conclusions:Regional correlation demonstrates that the Panxi—Hannan Arc does not extend into the Lower Yangtze region. The southern Lower Yangtze region was affected by the arc magmatism with a peak age of 840 Ma and related to subduction of the South China Ocean. We propose that the magmatism clustering at 840 Ma and the associated Nanhua Rift were products of the post-orogenic extension in the Jiangnan Orogen, and the magmatism clustering at 800 Ma and 750 Ma and propagation of the rift represent overall influence of the Rodinia breakup.关键词
下扬子地区/岩浆活动/新元古代/张八岭群/肥东杂岩/董岭杂岩Key words
Lower Yangtze region/magmatism/Neoproterozoic/Zhangbaling Group/Feidong Complex/Dongling Complex引用本文复制引用
李云剑,朱光,顾承串,张帅,刘程,牛漫兰,苏楠,肖世椰..肥东杂岩的锆石U-Pb年龄及其地质意义——兼论下扬子地区新元古代岩浆活动历史[J].地质论评,2018,64(3):551-568,18.基金项目
本文为国家自然科学基金项目(编号:41772228)的成果.This study was funded by the National Nature Science Foundation of China(No.41772228) （编号:41772228）
