摘要
吉林省中部伊通地区火山岩大地构造上位于华北板块北缘东段。本文对其进行了岩相学、LA-ICP-MS锆石U-Pb年代学和岩石地球化学特征的研究,进而探讨了火山岩的成因。伊通地区玄武安山岩中锆石均呈自形—半自形,具有明显的岩浆震荡生长环带和较高的Th/U值,表明其为岩浆成因。锆石定年结果表明玄武安山岩形成于(285±2)Ma,即早二叠世。伊通地区早二叠世火山岩的岩石组合为玄武安山岩和安山岩,样品SiO2质量分数为51.29%~58.91%,Mg#值为39~66,属于拉斑系列,相对富集轻稀土元素(LREEs)、大离子亲石元素(LILEs),亏损高场强元素(HFSEs)。综合研究认为伊通地区早二叠世火山岩岩浆来自受俯冲流体交代的亏损地幔楔,形成于古亚洲洋南向俯冲的活动大陆边缘环境。结合区域研究成果,认为华北板块北缘早二叠世处于古亚洲洋南向俯冲作用之下。
The volcanic rocks in the Yitong area of central Jilin Province are located in the eastern segment of the northern margin of the North China plate.This paper presents zircon LA-ICP-MS U-Pb geochronology and geochemical data of the volcanic rocks in this area,aiming to explore their petrogenesis.The zircons in the andesite present euhedral-subhedral,and obvious magmatic oscillation zone,with Th/U ratios of 0.06-0.95,indicating their magmatic origin.Zircon dating results indicate that basaltic andesites were formed at(285±2)Ma,the Early Permian.The rock assemblage of the Early Permian volcanic rocks is basaltic andesite and andesite.The SiO 2 mass fraction of the samples is 51.29%-58.91%,and the Mg#values are 39-66,belonging to the tholeiitic series,relatively enriched in light rare earth elements(LREEs),large ion lithophile elements(LILEs),and depleted in high field strength elements(HFSEs).Comprehensive studies suggest that the Early Permian volcanic magma originated from the depleted mantle wedge metasomatized by subducting fluids,and was formed in the active continental margin environment of the southward subduction of the Paleo-Asian Ocean.Combined with regional research results,it is believed that the northern margin of the North China plate was under the southward subduction of the Paleo-Asian Ocean in the Early Permian.
作者
牟芮霆
裴福萍
时玉芹
魏敬洋
Mu Ruiting;Pei Fuping;Shi Yuqin;Wei Jingyang(College of Earth Sciences,Jilin University,Changchun 130061,China;The Third Geological Survey of Jilin Province,Siping 136000,Jilin,China)
出处
《吉林大学学报（地球科学版）》
CAS
CSCD
北大核心
2023年第4期1117-1131,共15页
Journal of Jilin University：Earth Science Edition
基金
国家自然科学基金项目(41972053)。
关键词
锆石U-PB年代学
地球化学
火山岩
吉林中部
zircon U-Pb geochronology
geochemistry
volcanic rocks
central Jilin Province
