Petrogenesis of the Chaihulanzi Gneiss and its Tectonic Implications for the North China Craton  

作　　者：QU Yunwei XIE Yuling XIA Jiaming YU Chao XU Dong LI Xu SUN Li 

机构地区：[1]School of Civil and Resource Engineering,University of Science and Technology Beijing,Beijing 100083,China [2]Chaihulanzi Gold Mining Co.Ltd.(Shandong Gold Group),Chifeng,Inner Mongolia 024000,China

出　　处：《Acta Geologica Sinica(English Edition)》2021年第6期2016-2032,共17页地质学报（英文版）

基　　金：financially supported by the Ministry of Science and Technology of China(State Key Research Project No.2017YFC0601302);the Chifeng Chaihulanzi Gold Mining Co.Ltd.(Shandong Gold Group)。

摘　　要：The Chaihulanzi area in eastern Inner Mongolia is tectonically situated on the northern margin of the North China Craton(NCC). The main Precambrian lithologies of the area have been referred to the Archean Jianping Group metasupracrustal sequences. Based on field observations, petrographic, whole-rock geochemical, and zircon U-Pb geochronological results, a magmatic origin for the units is proposed. Our results show that the Chaihulanzi gneisses are mainly of granitic, dioritic and granodioritic compositions, and show typical magmatic rock textures and mineral assemblages. The dioritic and granodioritic gneisses show Na-rich tonalite–trondhjemite–granodiorite(TTG)-like affinity with zircon U-Pb dates of ca. 2.57–2.59 Ga, representing a juvenile continental growth for the northeastern NCC. The granitic gneiss is indeed potassic granite and yielded a zircon U-Pb date of ~2.50 Ga, which is contemporaneous with the Jining–Jiaoliao microblock collision(2.53–2.49 Ga), implying another crustal growth event. The well-developed gneissosity in 2.57–2.59 Ga dioritic and granodioritic gneisses together with the 2.5 Ga potassic granite, which crosscuts the gneissosity implies a 2.57–2.50 Ga(mainly 2.53–2.51 Ga) collisional orogeny, probably related to the Jining–Jiaoliao microblock collision. Our new geology and chronological results provide new evidence for the early Precambrian tectonic evolution of the NCC.

关 键 词：igneous petrology Precambrian tectonic evolution Archean gneiss North China Craton Jianping Group Chaihulanzi Inner Mongolia 

分 类 号：P588.3[天文地球—岩石学] P597.3[天文地球—地质学] P542