南羌塘索日卡地区三叠纪玄武岩锆石U-Pb年龄、地球化学特征及其地质构造意义
Zircon U-Pb Ages,Geochemistry,and Tectonic Significances of the Triassic Suorika Basalts in the Southern Qiangtang Terrane
摘要
Abstract
The Triassic period marks a pivotal era for the tectonic transformation of the Qiangtang block.To gain a deeper understanding of the amalgamation and orogeny of the South and North Qiangtang micro-blocks during the Triassic,as well as the evolution of the ocean and continent,this study conducted LA-ICP-MS zircon in-situ U-Pb isotopic dating and petrochemical analysis on the basalts from the southern side of the central orogenic belt in the South Qiangtang region,specifically the Sorika basalts.The basalt samples yielded zircon U-Pb weighted average ages of(245.1±2.5)Ma and(250.7±2.9)Ma,and exhibited SiO2 contents ranging from 45.2%to 52.9%,K2O contents ranging from 2.42%to 3.60%,MgO contents ranging from 3.16%to 6.22%,and Mg#values of 51-60,suggesting that they belong to the shoshonitic and calc-alkaline basalt series.They are characterized by high Ti/V(28 to 31)and Zr/Y(>7.53)ratios,enrichment of LREE with(LREE/HREE)N=15.44 to 19.96 and no Eu anomaly,low Nb/La ratios(<1),and depletion of Nb and Ta.They are considered continental basalts,and the basaltic magma was probably generated by partial melting of the mantle within the intraplate setting following the closure of the Longmucu-Shuanghu Ocean.Xenocrystic zircon gains from the Suorika basalts recorded multiple magmatic events at 2 512 Ma,1 816 Ma,1 277 to 1 019 Ma,800 Ma,558 Ma,420 Ma,and 340 Ma.These ancient crustal materials record information related to global Precambrian tectonic-magmatic-thermal events associated with the evolution of supercontinents such as Columbia,Rodinia,and Gondwana.关键词
玄武岩/地球化学/锆石U-Pb年龄/LA-ICP-MS/古老陆壳物质/南羌塘Key words
basalts/geochemistry/zircon U-Pb age/LA-ICP-MS/ancient crust/southern Qiangtang分类
地质学引用本文复制引用
陈云,陈冲,季长军,朱江,刘锦明,周连凤,王雅萍..南羌塘索日卡地区三叠纪玄武岩锆石U-Pb年龄、地球化学特征及其地质构造意义[J].地球学报,2025,46(3):506-518,13.基金项目
本文由国家自然科学基金项目(编号:41602122 （）
42172103 （）
U24A20597)、国家重大科技专项计划深地专项(编号:2024ZD1001005)、中国地质调查局项目(编号:DD20230024 （编号:2024ZD1001005）
DD20230315)、西藏自治区科技计划项目(编号:XZ202401YD0006 （）
XZ202403ZY0040)、湖北省自然科学基金项目(编号:2023AFD206 （）
2023AFD230 （）
2024AFD401)、资源与生态环境地质湖北省重点实验室开放基金资助项目(编号:HBREGKFJJ-202302 （）
HBREGKFJJ-202403)和地质过程与矿产资源国家重点实验室科技部专项经费(编号:GPMR202424)联合资助. This study was supported by National Natural Science Foundation of China(Nos.41602122,42172103,and U24A20597),National Science and Technology Major Project(No.2024ZD1001005),China Geological Survey(Nos.DD20230024 and DD20230315),Science and Technology Plan Project of Xizang(Nos.XZ202401YD0006 and XZ202403ZY0040),Natural Science Foundation of Hubei Province(Nos.2023AFD206,2023AFD230,and 2024AFD401),Hubei Key Laboratory of Re-sources and Eco-environment Geology(Nos.HBREGKFJJ-202302 and HBREGKFJJ-202403),and State Key Laboratory of Geological Processes and Mineral Resources(No.GPMR202424). （编号:GPMR202424）
