Destruction of the lower crust beneath the North China Craton recorded by granulite and pyroxenite xenoliths  

作　　者：Dongya ZOU Hongfu ZHANG 

机构地区：[1]School of Earth Sciences,Zhejiang University,Hangzhou,310027,China [2]Department of Geology,Northwest University,Xi’an,710069,China

出　　处：《Science China Earth Sciences》2023年第2期190-204,共15页中国科学（地球科学英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41688103&42003026)。

摘　　要：The lower crust beneath the North China Craton(NCC)was transformed during the craton destruction in the Mesozoic,however,the transformation processes are yet to be fully understood.Compositional and geochronological variations of granulite and pyroxenite xenoliths provided insights into the nature of the lower crust before and after the craton destruction.In this study,we summarized the latest results of geochemistry and zircon geochronology coupled with Hf-O isotopes from granulite and pyroxenite xenoliths hosted by Phanerozoic igneous rocks in NCC.Comparing previous studies on the granulite terranes and adakitic rocks of NCC,we aim to discuss the destruction processes of lower crust beneath the NCC.The granulite and pyroxenite xenoliths of NCC were divided into two and three groups,respectively,based on the differences of geochemical features.Group I granulite xenoliths from the NCC have silicic-basic compositions,with metamorphic ferrosilite.The Group I granulite xenoliths show relatively lower Mg#values of pyroxenes and whole-rock than that of the Group II granulite xenoliths,and enrichments of light rare earth elements and Sr-Nd isotopic compositions.Their zircons display Archean-Phanerozoic ages with three peaks of Neoarchean,Paleoproterozoic,and Mesozoic.Generally,Group I granulite xenoliths show close affinities to the granulite terranes of the NCC in terms of the major and trace elements and Sr-Nd isotopic compositions,with a consistent Archean-Proterozoic evolutionary history.However,Group I granulite xenoliths have abundant Phanerozoic zircons with variable Hf isotopic compositions from depleted to enriched,which could be formed by modifications of magma underplating.Therefore,Group I granulite xenoliths represent the modified ancient lower crust beneath the NCC.The Group II granulite and Group III pyroxenite xenoliths from the NCC have similar geochemical features and are basic in compositions,with metamorphic to magmatic orthopyroxenes.The Group II granulite and Group III pyroxenite xenoliths usually

关 键 词：North China Craton Destruction of lower crust Granulite xenolith Pyroxenite xenolith 

分 类 号：P542[天文地球—构造地质学]