地质与资源2025，Vol.34Issue(6)：698-705,8.DOI:10.13686/j.cnki.dzyzy.2025.06.003
吉林大车背沟地区南楼山组火山岩锆石U-Pb年代学及地球化学特征
Zircon U-Pb geochronology and geochemistry of the volcanic rocks of Nanloushan Formation in Dachebeigou area,Jilin Province
摘要
Abstract
The Dachebeigou area is located in the transitional zone between the Paleo-Asian Ocean and Paleo-Pacific tectonic domains.Detailed geological,petrographic,zircon U-Pb geochronological,and geochemical studies for the rhyolitic welded tuff of Nanloushan Formation in this area show that zircons extracted from the volcanic rocks are euhedral to subhedral,predominantly long-prismatic,and display clear oscillatory zoning,with Th/U ratios of 0.36-0.71(＞0.4),indicating a magmatic origin.Zircon U-Pb dating yields a Middle Jurassic age of 174±1.4 Ma(MSWD=1.6).Geochemically,the rocks belong to the calc-alkaline series,characterized by significant enrichment in LILEs(K and Ba),LREE,and active incompatible elements(Th and U),and relative depletion in HFSEs(Nb,P and Ti).They exhibit high Mg# values(0.47-0.57),with pronounced negative anomalies in Ta,Nb,and Ti.Combined with Nb/Ta and Ba/La ratios,it is suggested that the magma was derived from crust-mantle mixing.Furthermore,the Zr/Y and La/Yb ratios are generally consistent with those typical of an active continental margin setting.Combined with previous studies,it is concluded that the Middle Jurassic volcanic rocks of Nanloushan Formation in Dachebeigou area were formed in an active continental margin setting related to the subduction of the Paleo-Pacific Plate beneath the Eurasian Plate,providing key constraints on the tectonic evolution of the Paleo-Pacific Plate in this region.关键词
流纹质熔结凝灰岩/中侏罗世/地球化学/活动陆缘/吉林省Key words
rhyolitic welded tuff/Middle Jurassic/geochemistry/active continental margin/Jilin Province分类
天文与地球科学引用本文复制引用
张彬,王存柱,赵院冬,任龙,王春晖,时林,刘长纯,毛永新..吉林大车背沟地区南楼山组火山岩锆石U-Pb年代学及地球化学特征[J].地质与资源,2025,34(6):698-705,8.基金项目
中国地质调查局项目"吉林那尔轰一带金铜多金属找矿靶区优选与评价"(DD20230371)、"吉林大车背沟等8幅1∶5万矿产地质调查"(DD20208010). （DD20230371）
