Petrogenesis of the~1.94 Ga Meta-gabbronorites in Liangcheng:Implications for Tectonic Evolution of the Khondalite Belt,North China Craton  

作　　者：LIAN Guanghui REN Yunwei SHI Jianrong XU Zhongyuan FENG Fan 

机构地区：[1]College of Earth Sciences,Jilin University,Changchun 130061,China [2]Key Laboratory of Mineral Resources Evaluation in Northeast Asia,Ministry of Natural Resources,Changchun 130061,China [3]Tianjin Center,China Geological Survey,Tianjin 300170,China [4]Precambrian Geological Research Centre,China Geological Survey,Tianjin 300170,China

出　　处：《Acta Geologica Sinica(English Edition)》2023年第2期418-435,共18页地质学报（英文版）

基　　金：granted by the National Natural Science Foundation of China(Grant Nos.41872194,41872203);the Regional Geological Survey Project of Huai′an,Hebei-Liangcheng,Inner Mongolia(Grant No.DD20190035)。

摘　　要：We investigated the meta-gabbronorites in Liangcheng and used detailed petrography,geochemistry,zircon geochronological and in-situ Hf isotopic studies to clarify their formation and metamorphic ages,petrogenesis,tectonic setting and provide constraints on the tectonic evolution of Khondalite Belt(KB).The zircon U-Pb dating results show that the meta-gabbronorites crystallized at~1.94 Ga and were metamorphosed at~1.91–1.89 Ga.They can be subdivided into the low-Mg and high-Mg groups.The low-Mg meta-gabbronorites contain relatively lower MgO and higher SiO2 contents than high-Mg meta-gabbronorites.They are enriched in light rare earth elements and large ion lithophile elements,depleted in high field strength elements,and exhibit positive(high-Mg meta-gabbronorites)and negative(low-Mg metagabbronorites)Sr and Eu anomalies.The zircon in-situεHf(t)of meta-gabbronorites is 0.07–4.12,with Hf model ages(TDM)of 2169–2400 Ma.The meta-gabbronorites in Liangcheng originated from the asthenospheric mantle and experienced fractional crystallization of olivine,orthopyroxene,clinopyroxene,and plagioclase.They were contaminated by the crustal rocks(mainly khondalite series)during ascent,especially for low-Mg gabbronorites.The ridge subduction is the most plausible tectonic setting for meta-gabbronorites,indicating the eastern segment of KB was in a ridge subduction setting at~1.94 Ga following an orogenic thickening event during a prolonged orogenic process.

关 键 词：meta-gabbronorites PALEOPROTEROZOIC Liangcheng Khondalite Belt North China Craton 

分 类 号：P548[天文地球—构造地质学] P588.3[天文地球—地质学]