地质论评2026，Vol.72Issue(2)：355-374,20.DOI:10.16509/j.georeview.2025.08.015
大兴安岭南段白音高老组火山岩U-Pb年龄、地球化学特征及地质意义
U-Pb age and geochemical characteristics of volcanic rocks of Biyingaolao Formation in southern Great Hinggan Mountains and their geological significance
摘要
Abstract
In order to determine the formation age,petrogenesis,and formation environment of the volcanic rocks of the Biyingaolao Group in Xinchengzi Basin,southern Great Hinggan Mountains(Greater Xing'an Range),Inner Mongolia,this study conducted zircon U-Pb dating,elemental geochemistry,and Sr-Nd isotope studies on the rhyolitic volcanic rocks within the basin.The LA-ICP-MS zircon U-Pb ages of the rhyolitic volcanic rocks are 132.8±0.8 Ma and 133.1±1.8 Ma respectively,indicating that the rocks were formed in the Early Cretaceous.The rocks are rich in Si and alkali,rich in potassium,depleted in Mg,Ca and P,and belong to the peralkali and high potassium calc-alkaline series rocks.The LREE and HREE were obviously fractionated,and the LREE were enriched(LREE/HREE=8.24～11.35),with significant Eu anomaly(8Eu=0.49～0.85).The trace elements are rich in Rb,Ba,K and deficient in Sr,rich in HFSE Th,U,Zr,Hf and deficient in Nb,Ta and Ti.The rocks have high Yb content and Ga/Al ratio,showing similar characteristics to A-type granites.The(87Sr/86Sr)i values of the volcanic rocks range from 0.70243 to 0.70634,εNd(t)ranges from-3.6 to-4.2,and the corresponding two-stage Nd model ages range from 1221 Ma to 1265 Ma.Based on the regional geological data and the results of this paper,it is concluded that the volcanic magma of the Baiyingaolao Formation in Xinchengzi Basin originates may originate from anatexis of Paleoproterozoic plagioclase-amphibole rocks in the lower crust,facilitated by mantle-derived magma underplating and associated metasomatism,which is formed in the extensional tectonic setting,and may be related to the subduction of the paleo-Pacific plate to the East Asian continent.The rhyolite volcanic rocks of Baiyingaolao Formation in the basin have high U content,and the U released by the hydrothermal alteration provides uranium source for uranium mineralization in the area.关键词
白音高老组火山岩/锆石U-Pb定年/元素地球化学/Sr-Nd同位素/构造背景/新城子盆地/大兴安岭Key words
volcanic rocks/Bayingaolao Formation/zircon U-Pb dating/elemental geochemistry/Sr-Nd isotopes/tectonic Setting/Xinchengzi Basin/Great Hinggan Mountains引用本文复制引用
周舰,王天奇,王一鸣,郝晓飞,王常东,杨志亮,董小宇,王佳俐,吴燕清,林天发,于兵..大兴安岭南段白音高老组火山岩U-Pb年龄、地球化学特征及地质意义[J].地质论评,2026,72(2):355-374,20.基金项目
本文为中国核工业地质局铀矿地质勘查项目"河北省张北—内蒙古突泉地区铀—多金属矿资源调查评价与勘查"(编号:202312)的成果. （编号:202312）
