化工矿产地质2025，Vol.47Issue(4)：289-304,16.
大兴安岭北段诺敏大山地区白音高老组火山岩年代学、地球化学特征及其地质意义
Geochronology,Geochemical Characteristics of the Volcanic Rocks of the Baiyingaolao Formation in the Nuomin Mountain Area,Northern Greater Khingan Mountains and Their Geological Significance
摘要
Abstract
The volcanic rocks of the Baiyingaolao formation in the Nuomin Mountain Area,Oroqen Autonomous Banner,Inner Mongolia,are located in the northern Greater Khingan Mountains.By conducting systematic analyses of the field geological characteristics,petrology,geochemistry,and zircon U-Pb chronology of these volcanic rocks,this study seeks to identify their genetic type and tectonic setting.The volcanic rocks of the Baiyingaolao formation in the Nuomin Mountain Area are mainly composed of rhyolite and rhyolitic crystal tuff.LA-ICP-MS zircon U-Pb dating shows that the age of these volcanic rocks is 127.4±1.2 Ma,indicating that they formed during the late Early Cretaceous.The volcanic rocks are geochemically characterized by high SiO₂ and alkali contents but low CaO and MgO contents.The obvious negative Eu anomaly,relative enrichment of Rb,Th,U,and K,relative depletion of Ba,Sr,P,and Ti,as well as high total iron oxide(FeOT)/MgO and(Na2O+K2O)/CaO values,all exhibit the characteristics of highly fractionated I-type and A-type granites.Meanwhile,combined with the temperature and pressure conditions of magma generation,this study suggests that these volcanic rocks may have been formed by the partial melting of shallow crust-derived materials(with incorporation of mantle-derived materials)under low-pressure and high-temperature conditions,followed by fractional crystallization.Combined with the spatiotemporal evolution of Late Jurassic-Early Cretaceous volcanic rocks in Northeast China,this study reveals that the Nuomin Mountain Area in the northern segment of the Greater Khingan Mountains was under an extensional geodynamic setting during the late Early Cretaceous.This setting may be closely related to the delamination of the previously thickened continental crust associated with the Mongol-Okhotsk Ocean tectonic system,may result from the subduction-rollback of the Paleo-Pacific Plate,or even may be driven by the combined effect of these two processes.关键词
I型花岗岩/A型花岗岩/LA-ICP-MS锆石U-Pb定年/早白垩世晚期/伸展构造环境/大兴安岭北段Key words
I-type granite/A-type granite/LA-ICP-MS zircon U-Pb dating/Late Early Cretaceous/Extensional tectonic setting/Northern Greater Khingan Mountains分类
天文与地球科学引用本文复制引用
Wu Jingyi,Zhao Dongfang,Wang Shuai..大兴安岭北段诺敏大山地区白音高老组火山岩年代学、地球化学特征及其地质意义[J].化工矿产地质,2025,47(4):289-304,16.基金项目
内蒙古自治区地质勘查基金内蒙古自治区呼伦贝尔市诺敏大山等三幅1∶5万区域矿产地质调查(编号:NMKD2015-18) （编号:NMKD2015-18）
