Material records for Mesozoic destruction of the North China Craton by subduction of the Paleo-Pacific slab  

作　　者：Yazhou FENG Jinhui YANG Jinfeng SUN Jiheng ZHANG 

机构地区：[1]State Key Laboratory of Lithospheric Evolution,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China [2]University of Chinese Academy of Sciences,Beijing 100049,China [3]Innovation Academy for Earth Science,Chinese Academy of Sciences,Beijing 100029,China

出　　处：《Science China Earth Sciences》2020年第5期690-700,共11页中国科学（地球科学英文版）

基　　金：supported by the Ministry of Science and Technology of People’s Republic of China(Grant No.2016YFC0600109);the National Natural Science Foundation of China(Grant No.41688103).

摘　　要：It is well known that the destruction of the North China Carton(NCC)is closely related to subduction of the Paleo-Pacific slab,but materials recording such subduction has not been identified at the peak time of decratonization.This paper presents data of whole-rock major and trace elements and Sr-Nd-Hf isotopes and zircon U-Pb ages and Hf-O isotopes for Mesozoic volcanic rocks from the Liaodong-Jinan region in the northeastern NCC,in order to trace the subduction-related materials in their source and origin.The Mesozoic volcanic rocks in the Liaodong-Jinan region are mainly composed of two series of rocks,including alkaline basaltic trachyandesite,trachyandesite and trachyte,and subalkaline trachyandesite and andesite.Zircon U-Pb dating yields eruption ages of 129–124 Ma for these rocks.The Early Cretaceous volcanic rocks are all enriched in LILEs(such as Rb,Sr,Ba and Th)and LREEs,depleted in HFSEs(such as Nb,Ta and Ti),indicating that they were originated from mantle sources that had been modified by subducted crustal materials.However,they have relatively heterogeneous and variable isotopic compositions.The alkaline basaltic trachyandesite,trachyandesite and trachyte have enriched whole-rock Sr-Nd-Hf and zircon Hf isotopic compositions and mantle-likeδ18O values,suggesting that they were derived from low-degree partial melting of an isotopically enriched lithospheric mantle source.In contrast,the subalkaline trachyandesite and andesite have relatively depleted isotopic compositions with zirconεHf(t)values up to+5.2 and heavy zircon O isotopic compositions with δ18O values of+8.1‰to+9.0‰,indicating that they were originated from a lithospheric mantle source that had been metasomatized by melts/fluids derived from the recycled low-T altered oceanic basalt.All of these geochemical features suggest that the Early Cretaceous volcanic rocks in the Liaodong-Jinan region would result from mixing of mafic magmas with different compositions.Such magmas were originated from the enriched lithospheric mantle and th

关 键 词：North China CRATON Early CRETACEOUS VOLCANIC rocks Zircon Hf-O isotopes SUBDUCTION of the Paleo-Pacific slab 

分 类 号：P597[天文地球—地球化学] P542[天文地球—地质学]