西秦岭白龙江地区志留系迭部组岩石地球化学特征及碎屑锆石原位U-Pb年代学研究  

Geochemistry Characteristics and Detrital Zircon In-Site U-Pb Geochronology of Silurian Diebu Formation in Bailongjiang Area, West Qinling Mountains

作　　者：俞胜 贾轩 姚皓骞 徐磊 赵斌斌 贾新勇 YU Sheng;JIA Xuan;YAO Haoqian;XU Lei;ZHAO Binbin;JIA Xinyong(The Second Institute of Geology and Minerals Exploration,Gansu Provincial Bureau of Geology and Minerals Exploration and Development,Lanzhou 730020,Gansu,China;School of Earth Science and Resources,China University of Geosciences(Beijing),Beijing 100083;Geological Survey of Gansu Province,Lanzhou 730000,Gansu,China)

机构地区：[1]甘肃省地质矿产勘查开发局第二地质矿产勘查院,甘肃兰州730020 [2]中国地质大学(北京)地球科学与资源学院,北京100083 [3]甘肃省地质调查院,甘肃兰州730000

出　　处：《西北地质》2023年第5期245-261,共17页Northwestern Geology

基　　金：甘肃省科技计划项目“甘肃北山成宣镁铁质–超镁铁质杂岩体成因与找矿潜力研究”(21JR7RA787);甘肃省自然资源厅项目“甘肃省迭部县尖尼–洛大地区1∶5万矿产远景调查”(甘国土资财发[2015]16号、甘国土资财发[2016]15号、甘财经二[2017]62号)联合资助。

摘　　要：白龙江地区志留系迭部组浅变质碎屑岩微量元素地球化学指示其物源主要来自上地壳长英质岩浆岩,源区与活动大陆边缘背景密切有关。迭部组LA–ICP–MS碎屑锆石U–Pb年代学显示年龄值跨度较大,最小年龄为440 Ma,指示其沉积时代不早于早志留世,结合区域化石资料限定迭部组为早志留世。碎屑锆石U–Pb年龄可分出440~680 Ma、798~876 Ma、1012~1291 Ma、1590~1990 Ma、2113~2455 Ma等5个峰值年龄区间,显示区内沉积物源具有多源多时代地质体的贡献特征。其中,最高峰值440~680 Ma(占总有效数据76.9%)的年龄谱图与北秦岭微地块吻合度高,显示迭部组沉积物源主要来自北秦岭微地块,而其他组少量峰值碎屑锆石年龄则显示南秦岭微地块、扬子地块,北祁连东段可能参与了部分物源供给。Trace element geochemistry of the shallow metamorphic clastic rocks of the Silurian Diebu Formation in the Bailongjiang area indicates that their provenance is mainly derived from felsic magmatic rocks in the upper crust,and the source area is closely related to the background of the active continental margin.LA–ICP–MS detrital zircon U–Pb chronology of the Diebu Formation shows a large age span,with a minimum age of 440 Ma,indicating that its sedimentary age is not earlier than the Early Silurian.Combined with regional fossil data,the Diebu Formation is defined as the Early Silurian.The U–Pb ages of detrital zircons can be divided into five peak age ranges of 440~680 Ma,798~876 Ma,1012~1291 Ma,1590~1990 Ma,and 2113~2455 Ma, indicating that the sediment sources in the area have the contribution characteristics of multiple sources and multiple ages of geological bodies. The age spectrum with the highest peak value of 440~680 Ma (accounting for 76.9% of the total effective data) is highly consistent with the north Qinling microblock, indicating that the sediment sources of the Diebu Formation mainly come from the north Qinling microblock, while a small amount of peak clastic zircon ages of other groups indicate that the south Qinling microblock, the Yangtze block, the eastern section of the north Qilian mountains may participate in some source supply.

关 键 词：迭部组 地球化学 碎屑锆石 U–Pb年代学 

分 类 号：P595[天文地球—地球化学]