吉林延边五凤地区早侏罗世粗面安山岩岩石成因  

PETROGENESIS OF THE EARLY JURASSIC TRACHYANDESITE IN WUFENG AREA OF YANBIAN,JILIN PROVINCE

作　　者：高子越 鞠楠 李经纬[1] 杨群 王可勇[3] GAO Zi-yue;JU Nan;LI Jing-wei;YANG Qun;WANG Ke-yong(School of Earth Sciences and Resources,China University of Geosciences,Beijing 100089,China;Shenyang Center of China Geological Survey,Shenyang 110034,China;College of Earth Sciences,Jilin University,Changchun 130061,China)

机构地区：[1]中国地质大学地球科学与资源学院,北京100089 [2]中国地质调查局沈阳地质调查中心,辽宁沈阳110034 [3]吉林大学地球科学学院,吉林长春130061

出　　处：《地质与资源》2024年第1期12-23,40,共13页Geology and Resources

基　　金：国家自然科学基金项目“碱性岩浆作用中铌钽元素富集机制研究:以辽东地区赛马铌钽矿床为例”(42102087);中国博士后科学基金项目“辽东地区碱性岩型铌钽矿床成因研究”(2022M712966);科技部重大专项“青藏高原大宗矿产数据库建设”(2021QZKK0304).

摘　　要：以吉林省延边五凤地区粗面安山岩为对象,开展岩石学、LA-ICP-MS锆石U-Pb年代学和全岩地球化学研究,查明其SiO_(2)含量为58.33%~61.36%,K2O含量1.61~3.28%,全碱含量为6.77%~10%,属于中钾-高钾钙碱性系列.岩浆成因锆石^(206)Pb/^(238)U加权平均年龄为175.52±2.7 Ma,与早侏罗世古太平洋板块俯冲时间一致.岩石相对富集K、Ba、Rb等大离子亲石元素和Th、U等强不相容元素,亏损Nb、Ta、Ti等高场强元素,LREE/HREE比值较高,具有轻稀土富集、重稀土亏损的特征,表明岩浆可能源于地幔部分熔融,其源区受到俯冲的壳源物质交代.研究认为粗面安山岩形成于大洋俯冲系统的活动大陆边缘,属于早侏罗世古太平洋板块俯冲的岩浆响应.Study on the petrology,LA-ICP-MS zircon U-Pb dating and whole rock geochemistry of the trachyandesite in Wufeng area of Yanbian,Jilin Province in Northeast China,shows that the SiO_(2)content is 58.33%-61.36%,K2O content 1.61%-3.28%and total alkali content 6.77%-10%,belonging to the medium potassium-high potassium calc-alkaline series.The weighted mean age of magmatic zircon^(206)Pb/^(238)U is 175.52±2.7 Ma,which is consistent with the subduction time of Early Jurassic paleo-Pacific plate.The trachyandesite is characterized by relative enrichment of LILEs(K,Ba and Rb)and strongly incompatible elements(Th and U),and depletion of HFSEs(Nb,Ta and Ti),with high LREE/HREE ratio,and enriched LREEs and depleted HREEs,indicating that the magma may originate from the partial melting of mantle and its source area is metasomatized by the subducted shell source materials.From the above,it is believed that the trachyandesite was formed in the active continental margin of oceanic subduction system and was the magmatic response to the subduction of Early Jurassic paleo-Pacific plate.

关 键 词：粗面安山岩 岩石地球化学 锆石U-PB年龄 古太平洋板块 早侏罗世 活动大陆边缘 吉林省 

分 类 号：P595[天文地球—地球化学] P597[天文地球—地质学]