Geochronology,Mineralogy,and Geochemistry of the Tonsteins from the Permo–Carboniferous Benxi Formation,Ordos Basin,North China Craton  

作　　者：WANG Luojing LÜDawei ZHANG Zhihui James C.HOWER Munira RAJI ZHANG Yushuai SHEN Yangyang GAO Jie 

机构地区：[1]Shandong Provincial Key Laboratory of Depositional Mineralization and Sedimentary Minerals,College of Earth Sciences and Engineering,Shandong University of Science and Technology,Qingdao,Shandong 266590,China [2]University of Kentucky,Center for Applied Energy Research,Lexington,KY 40511,USA [3]Sustainable Earth Institute,University of Plymouth,Devon PL48AA,UK

出　　处：《Acta Geologica Sinica(English Edition)》2023年第5期1355-1371,共17页地质学报（英文版）

基　　金：supported by the National Natural Science Foundation of China(Grant Nos.41972170,42102127);Shandong Provincial Natural Science Foundation(Grant No.ZR2021QD087);Chinese Postdoctoral Science Foundation(Grant No.2021M702019);SDUST Research Fund(Grant No.2018TDJH101)。

摘　　要：Tonstein layers are found worldwide in the Permo-Carboniferous coal-bearing strata.This study investigates the geochronology,mineralogy,and geochemistry of four tonstein samples from the Permo-Carboniferous Benxi Formation,Ordos Basin,North China Craton(NCC).The typical features of the studied tonsteins include thin beds,lateral continuity,angular quartz grains,and euhedral zircons with similar U-Pb ages,indicating a significant pyroclastic origin.In addition,the tonstein samples have low TiO_(2)/Al_(2)O_(3)ratios(<0.02)and rare earth elements and yttrium(REY)concentrations with obvious negative Eu anomalies,indicating that the tonsteins have a felsic magma origin.Moreover,compared with the mean composition of clay shale,the studied tonsteins are characterized by high concentrations of the elements Nb and Ta,which may affect the concentration of the corresponding elements in surrounding coal seams.The zircon U-Pb ages of the tonsteins(293.9-298.8 Ma)provide a precise chronological framework on the Benxi Formation in the Ordos Basin,constraining the Gzhelian-Aselian stages.The tonsteins were probably sourced from arc volcanism along the western margin of the NCC during the early Permian,implying that the Alxa Terrane had not amalgamated with the NCC at that time.

关 键 词：tonsteins GEOCHEMISTRY Permo–Carboniferous North China Craton 

分 类 号：P57[天文地球—矿物学] P534.4[天文地球—地质学]