地质学报2018，Vol.92Issue(3)：503-519,17.
鲁西临朐地区早白垩世青山群火山岩的年代学、地球化学及岩石成因
Geochronology, Geochemistry and Petrogenesis of the Early Cretaceous Volcanic Rocks of the Qingshan Group in the Linqu Area, Western Shandong Province
摘要
Abstract
In this paper,we report the geochronology,major and trace element geochemistry and Sr-Nd-Hf isotope data for the early Cretaceous volcanic rocks of the Qingshan Group in the Linqu area,with an objective to constrain the petrogenesis.The volcanic rocks are mainly intermediate rocks,with a SiO2 content varying between 54.41％～67.81％.Rock association consists mainly of andesite,trachyandesite,trachyte and trachydacite.These volcanic rocks belong to calc-alkaline series.Zircon LA-ICP-MS U-Pb dating yields an age of 121.3 ± 1.5 Ma for trachyandesite,indicating that the rocks crystallized in Early Cretaceous.The rocks are geochemically characterized by enrichment of LREE and LILE (e.g.,Rb,Ba,K),and depletion of HFSE (e.g.,Nb,Ta,Ti).These volcanic rocks have enriched Sr-Nd isotopic compositions ((87Sr/86Sr)t =0.704346～0.705831,εNd (t) =-14.6～-9.5),and have low Hf isotopic composition (εHf(t)=-29.3～-21.6).The rocks have the similar Mg# values as the melts produced by metabasite,with large range of Cr (26.7×10-6～239× 10-6) and Ni (10× 10-6 ～69.7× 10-6) content,and show significant mineral textural disequilibrium.The study further indicates that the Linqu volcanic rocks of the Qingshan Group may be the product of magma mixing between lower crust-derived melts of ancient North China Craton and mantle-derived melts of enriched mantle under the lithospheric extension setting.关键词
鲁西/青山群/火山岩/临朐/岩浆混合/锆石U-Pb年龄Key words
western Shandong/Qingshan Group/volcanic rocks/Linqu area/magma mixing/zircon U-Pb age引用本文复制引用
曹光跃,薛怀民,刘哲,路增龙..鲁西临朐地区早白垩世青山群火山岩的年代学、地球化学及岩石成因[J].地质学报,2018,92(3):503-519,17.基金项目
本文为科技部国际合作与交流专项(编号2014DFR21270)、深部探测技术与实验研究国家专项(编号SinoProbe-05-05)和地质调查局项目(编号12120114085401、121201102000150021)资助成果. （编号2014DFR21270）
