Geochronology and Hf Isotopes of Granite Gravel from Fanjingshan, South China: Implication for the Precambrian Tectonic Evolution of Western Jiangnan Orogen  

作　　者：Jinbao Su Yueqiao Zhang Shuwen Dong Xuanhua Chen Yong Li Jianjun Cui 

机构地区：[1]School of Earth Sciences and Engineering, Hohai University [2]Institute of Geomechanics,Chinese Academy of Geological Sciences [3]Chinese Academy of Geological Sciences

出　　处：《Journal of Earth Science》2014年第4期619-629,共11页地球科学学刊（英文版）

基　　金：supported by the SinoProbe-Deep Exploration in China (No. SinoProbe-08-01);the National Natural Science Foundation of China (No. 41202154);the China Geological Survey (Nos. 1212011120184, 1212011220261)

摘　　要：The debate of assembly time between the Yangtze and Cathaysia blocks has aroused the disputation on the formation mechanism of Jiangnan orogen, South China. Therefore widespread magmatism of 830-750 Ma in South China is interpreted as the product of either plume or arc magmatism, which results in distinctive depositional background in the Neoproterozoic. Granite gravel located at the unconformity between the Banxi Group and Fanjingshan Group of the western Jiangnan orogen was collected, which gave a new age limit to the deposition of the Banxi Group and Nanhu rift. Zircons from the granite gravel crystallized yield a weighted mean 2~6pb/238U age of 789~11 Ma, which probably represents the end of the Jiangnan orogeny and marks the onset of Nanhua rift. These zircons have negative εHf（t） of -2.1 to -6.0, with TDM of 1.38-1.52 Ga and Tcrust of 1.81-1.98 Ga indicating an old continental crust origin for the granite.The debate of assembly time between the Yangtze and Cathaysia blocks has aroused the disputation on the formation mechanism of Jiangnan orogen, South China. Therefore widespread magmatism of 830-750 Ma in South China is interpreted as the product of either plume or arc magmatism, which results in distinctive depositional background in the Neoproterozoic. Granite gravel located at the unconformity between the Banxi Group and Fanjingshan Group of the western Jiangnan orogen was collected, which gave a new age limit to the deposition of the Banxi Group and Nanhu rift. Zircons from the granite gravel crystallized yield a weighted mean 2~6pb/238U age of 789~11 Ma, which probably represents the end of the Jiangnan orogeny and marks the onset of Nanhua rift. These zircons have negative εHf（t） of -2.1 to -6.0, with TDM of 1.38-1.52 Ga and Tcrust of 1.81-1.98 Ga indicating an old continental crust origin for the granite.

关 键 词：Jiangnan orogeny Nanhua rift RODINIA Neoproterozoic. 

分 类 号：P597.3[天文地球—地球化学] P588.121[天文地球—地质学]