Petrogenesis of Mesoarchean TTG and Potassic Granite Suit in Wengmen Complex,Southern Dabie Orogen:Implications for Early Crustal Evolution of Yangtze Block
Xu Daliang
Peng Lianhong
Deng Xin
Tong Xirun
Xu Yang
Jin Xinbiao
Abstract：The late Archean(3.0-2.5 Ga)is a pivotal period when the composition of the continental crust and the tectonics style significantly changed.Abundant Mesoarchean granitoids,including TTG gneisses and potassic granitoids,occur in the Wengmen complex within the southern Dabie Orogen,part of the North Yangtze Block.Here,it presents major and trace elements,zircon U-Pb ages and Lu-Hf isotopes of these granitoids,which were integrated to determine their petrogenesis and constrain the crustal evolution of the Yangtze Block.The TTG gneisses and potassium granite veins have similar emplacement ages from 2 927 Ma to 2 917 Ma.The TTG gneisses can be divided into two types:low-HREE type and high-HREE type.Compared with the typical Archean TTGs,the low-HREE TTGs have moderate SiO2 and Na2O content,lower Mg#,Ni,Cr contents and Sr/Y ratio,showing the characteristics of low pressure TTGs.The high-HREE TTGs have lower Mg#,Ni,Cr contents and a very low Sr/Y ratio,which should belong to the transitional TTGs.The potassic granite veins are characterized by high SiO2,K2O,high K2O/Na2O(0.81-1.09)and iron-rich,exhibiting a left-leaning"V-type"seagull-type rare earth distribution pattern,indicative of highly differentiated granites.Their magmatic oxygen fugacity and water content resemble those of modern arc magmas.Zircons from the TTG gneisses gave εHf(t)values of-3.7-+1.5 and Hf crustal model ages(TDMC)of 3.56-3.23 Ga,whereas those from the potassic granites show εHf(t)values of-4.3-+0.2 and TDMC ages of 3.58-3.31 Ga.The coeval occurrence of TTGs and K-rich granitoids of the Wengmen complex within the southern Dabie Orogen marks the development of plate tectonics,the maturation of the continental crust and initial cratonization of the North Yangtze Block during the Mesoarchean.
Keywords：Yangtze BlockDabie OrogenArcheanTTGpotassic granitemagmatic oxygen fugacitygeochronology
Publication Date：2025-07-30
Online Publishing Date：2025-08-15(First online date of this platform, not the publication date of the document)
Pages：15( 2628-2642 )