Zircon U-Pb ages and O-Hf isotopes of Quaternary trachytes from the East Sea:Implications for the genesis of low-δ^(18)O magmas
作者机构：Dokdo Research CenterEast Sea Research InstituteKorea Institute of Ocean Science and TechnologyUljin 36315Republic of Korea Deep-Sea and Seabed Mineral Resources Research CenterKorea Institute of Ocean Science and TechnologyBusan 49111Republic of Korea Division of Science EducationKangwon National University1 Gangwondaehak-gilChuncheon-siGangwon-do 24341Republic of Korea
出 版 物：《Geoscience Frontiers》 (地学前缘（英文版）)
年 卷 期：2024年第15卷第2期
页 面：41-54页
核心收录：
学科分类：070902[理学-地球化学] 0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：This research was supported by a project on the sustainable research and development of Dokdo(Grant No.PG52911) which is funded by the Ministry of Oceans and Fisheries,South Korea
主 题：Quaternary intraplate volcanism East Sea Zircon O-Hf isotopes Low-δ^(18)O magma Recycled juvenile oceanic crust
摘 要：Quaternary intraplate magmatism formed several volcanic islands and seamounts,including Dokdo(DD),Ulleungdo(UD),Simheungtack(ST),Anyongbok,and Isabu in the southwest of the East Sea back-arc *** this study,we present whole-rock geochemical,zircon U–Pb age,and in situ O–Hf isotope data for the submerged volcanic rocks from DD,UD,and ST to provide new insights into the eruption timing of these volcanoes and constrain the magma evolution *** samples used in this study were trachytes and exhibited ferroan,alkalic,and metaluminous to weakly peraluminous *** showed light rare earth element(REE)-enriched patterns with(La/Yb)N ratios of 25.3–31.7 and mostly negative Eu anomalies in a chondrite-normalized REE *** addition,they were enriched in large-ion lithophile elements and high field strength elements;they exhibited positive Pb anomalies and strongly negative Ba,Sr,P,and Ti *** zircons yielded a weighted-mean 206Pb/238U age of 2.61,0.348–0.704,and 2.76–2.94 Ma for the DD,UD,and ST trachytes,*** zircons exhibited lowerδ^(18)O values than normal depleted mantle values,regardless of the crystallization age and spatial distribution of ***δ^(18)O values showed no correlation with U contents or Th/U ratios,indicating that the lowδ^(18)O signatures were of primary magmatic *** Hf isotopic compositions of the zircons were relatively heterogeneous but predominately characterized by positive eHf *** O–Hf mixing modeling revealed that low-δ^(18)O rocks with positive eHf values from the UD and ST volcanoes were derived from a hybrid source of recycled juvenile crustal materials with low-δ^(18)O and positive eHf signatures and an enriched mantle source with normalδ^(18)O and negative eHf *** juvenile oceanic crust in the source was likely metasomatized by seawater at high temperatures prior to *** contrast,the felsic magma that formed the DD volcanoes may have assimilated with regional
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