地质学报（英文版）2009，Vol.83Issue(2)：245-257,13.
Chronology and Geochemistry of Mesozoic Volcanic Rocks in the Linjiang Area, Jilin Province and their Tectonic Implications
Chronology and Geochemistry of Mesozoic Volcanic Rocks in the Linjiang Area, Jilin Province and their Tectonic Implications
摘要
Abstract
Zircon U-Pb ages and geochemical analytical results are presented for the volcanic rocks of the Naozhigou, Ergulazi, and Sidaogou Formations in the Linjiang area, southeastern Jilin Province to constrain the nature of magma source and their tectonic settings. The Naozhigou Formation is composed mainly of andesite and rhyolite and its weighted mean 206Pb/238U age for 13 zircon grains is 2224±1 Ma. The Ergulazi Formation consists of basaltic andesite, basaltic trachyandesite, and andesite, and six grains give a weighted mean 206Pb/238U age of 131±4 Ma. The Sidaogou Formation consists mainly of trachyandesite and rhyolite, and six zircon grains yield a weighted mean 206Pb/238U age of113±4 Ma. The volcanic rocks have SiO2=60.24%-77.46%, MgO=0.36%-1.29% (Mg#=0.32-0.40) for the Naozhigou Formation, SiO2=51.60%-59.32 %, MgO=3.70 %-5.54% (Mg#=0.50-0.60) for the Ergulazi Formation, and SiO2=58.28%-76.32%, MgO=0.07%-1.20% (Mg#=0.14-0.46) for the Sidaogou Formation. The trace element analytical results indicate that these volcanic rocks are characterized by enrichment in light rare earth elements (LREEs) and large ion lithophile elements (LILEs), relative depletion in heavy rare earth elements (HREEs) and high field strength elements (HFSEs, Nb, Ta, and Ti), and negative Eu anomalies. Compared with the primitive mantle, the Mesozoic volcanic rocks in the Linjiang area have relatively high initial 87Sr/86Sr ratios (0.7053-0.7083) and low eNd(t) values (-8.38 to -2.43), and display an EMII trend. The late Triassic magma for the Naozhigou Formation could be derived from partial melting of a newly accretional crust with the minor involvement of the North China Craton basement and formed under an extensional environment after the collision of the Yangtze Craton and the North China Craton. The Early Cretaceous volcanic rocks for the Ergulazi and Sidaogou Formations could be formed under the tectonic setting of an active continental margin related to the westward snbduction of the Izanagi plate.关键词
LA-ICP-MS zircon U-Pb dating/geochemistry/volcanic rocks/magma source/tectonic setting/Linjiang area/JilinKey words
LA-ICP-MS zircon U-Pb dating/geochemistry/volcanic rocks/magma source/tectonic setting/Linjiang area/Jilin分类
天文与地球科学引用本文复制引用
YU Yang,XU Wenliang,PEI Fuping,YANG Debin,ZHAO Quanguo..Chronology and Geochemistry of Mesozoic Volcanic Rocks in the Linjiang Area, Jilin Province and their Tectonic Implications[J].地质学报（英文版）,2009,83(2):245-257,13.基金项目
This paper is supported by the National Natural Science Foundation of China(Grant No.40672038). （Grant No.40672038）
