西北地质2018，Vol.51Issue(1)：125-136,12.
青海南祁连晚奥陶世火山岩LA-MC-ICPMS锆石U-Pb年龄及其地球化学特征
LA-MC-ICPMS Zircon U-Pb Dating and Geochemical Characteristics of Late Ordovician Volcanic Rocks in Southern Qilian Mountains, Qinghai Province
摘要
Abstract
Duosuoqu Formation in the Southern Qilian Mountains is composed of pyroclastic rocks,volcanic lava and sedimentary rocks,and its rock types vary from basalt to dacite,belonging to Calc-alkaline series combination.Using LA-MC-ICPMS zircon U-Pb dating,the authors obtained the 206Pb/238U weighted average age of (449.9 ±1.5) Ma and (449.5 ±1.8) Ma for the first time in the Duoosuo Formation volcanic rocks,which proves that these volcanic rocks were formed in late Ordovician.The results of geochemical analysis show that these volcanic rocks have high Al2O3and low TiO2,and they are enriched in LILE element (Sr,Rb,Ba),incompatible high field strength elements (U,Th) and LREE (La,Ce),but depleted in Ta,Nb,P,Ti and strong compatible elements (Cr,Ni).These volcanic rocks have relatively high ∑REE,with enrichment LREE,weak positive Eu anomalies to weak negative Eu anomalies.Comprehensive analysis shows that these volcanic rocks were formed in an activity continental margin/island arc environment.关键词
南祁连/多索曲组/晚奥陶世火山岩/LA-MC-ICPMS锆石U-Pb定年Key words
Southern Qilian Mountains/Duosuoqu Formation/Late Ordovician volcanic rocks/LA-MC-ICPMS ziron U-Pb dating分类
天文与地球科学引用本文复制引用
白旭东,杨波,赵忠国,欧阳光文,张志青,郝呈禄..青海南祁连晚奥陶世火山岩LA-MC-ICPMS锆石U-Pb年龄及其地球化学特征[J].西北地质,2018,51(1):125-136,12.基金项目
中国地质调查局国土资源大调查“青海木里地区六幅1∶5万区调”项目(1212011121189) （1212011121189）
