Episodic crustal growth and reworking at the southeastern margin of the North China Craton: evidence from zircon U–Pb and Lu–Hf isotopes of Archean tonalite–trondhjemite–granodiorite gneisses in the Bengbu-Wuhe area  

作　　者：Jianjun Wan Andong Wang Jiayong Pan Chengdong Liu Yan Zhao Zhengbing Zhou Xiandong Luo 

机构地区：[1]State Key Laboratory of Nuclear Resources and Environment,East China University of Technology,Nanchang 330013,China [2]College of Earth Sciences,East China University of Technology,Nanchang 330013,China [3]State Key Laboratory of Continental Dynamics,Northwest University,Xi'an 710069,China [4]Geological Exploration Technology Institute of Anhui Province,Hefei 230041,China

出　　处：《Acta Geochimica》2021年第3期366-389,共24页地球化学学报（英文）

基　　金：supported by the National Natural Science Foundation of China(Nos.41303041 and41763005);Open Fund(Nos.Z1909,Z1912,RGET1804,15LCD08)of the State Key Laboratory of Nuclear Resources and Environment;Fundamental Science on Radioactive Geology and Exploration Technology Laboratory;State Key Laboratory of Continental Dynamics。

摘　　要：The cratonization history of the North China Craton(NCC)and the nature of tectonothermal events are still highly controversial.Tonalite-trondhjemite-granodiorite(TTG)gneisses,as the dominant lithological assemblages in Archean metamorphic terranes,can provide significant clues to the magmatic and metamorphic evolution of Precambrian crust.This study presents zircon laser-ablation inductively-coupled-plasma mass spectrometry U–Pb ages,trace-element,and in-situ LA-MC-ICPMS zircon Hf isotope data for the TTG gneisses from the Bengbu-Wuhe area on the southeastern margin of the NCC.Cathodoluminescence images and trace elements indicated that magmatic zircons display the characteristics of euhedral-subhedral crystals with oscillatory growth zoning structures,high RREE contents,marked Ce positive anomalies,and Pr–Eu negative anomalies.The metamorphic zircons display the spherical-oval crystals with distinct core-rim structures,high and homogeneous luminescent intensity,lower RREE,Nb,Ta,Hf contents,relative flat REE patterns,weak Ce positive anomalies,and Pr-Eu negative anomalies.The Ti–in–zircon geothermometer data indicate that the crystallization temperature of the TTG gneiss ranged from 754 to 868℃.Zircon U–Pb ages indicate that the TTG gneisses formed at 2.79–2.77 Ga and 2.50 Ga and underwent metamorphism at 2.57–2.52 Ga.The Hf isotopic data indicate that the magmatic zircons exhibit high,positive eHf(t)values close to those of the coeval depleted mantle,whereas the metamorphic zircons exhibit negative or nil eHf(t)values.This implies that the TTG gneisses were derived from the partial melting of the~2.9–2.6 Ga juvenile crustal sources mixed with~3.0–2.8 Ga ancient crustal materials.Combined with the regional tectonic evolution,we propose that the metamorphic basement at the southeastern margin of the NCC underwent episodic crustal growth at~2.7 and~2.5 Ga and subsequently underwent crustal reworking or re-melting of the ancient crust during the Neoarchean.The Neoarchean TTG gneisses might have b

关 键 词：In-situ zircon Hf isotope Neoarchean North China Craton TTG gneiss Zircon U–Pb dating 

分 类 号：P534.2[天文地球—古生物学与地层学] P588.1[天文地球—地质学] P597.3