Integrated Analyses Constraining the Provenance of Early Cretaceous Huicheng Basin,Western Qinling Orogenic Belt

The Huicheng basin is a well-preserved basin in the West Qinling orogenic belt.The Tianjiaba Formation,Zhoujiawan Formation and Jishan Formation in the Early Cretaceous Huicheng basin are glutenite sedimentary successions.Paleocurrent and conglomerate composition indicate sediments are proximal developed from southern and northern margin.Heavy mineral analysis result suggests source rock of Early Cretaceous sandstones are predominant magmatic rocks,minor metamorphic rocks and sedimentary rocks.Chemical classification of Early Cretaceous sandtones indicates that the analysed sediments are unstable wackes and arkose/litharenite.The REE patterns are characterized by LREE enrichment,flat HREE,and poor negative Eu-anomalies.Various diagrams for sedimentary provenance using major and trace elements show all the sediments studied were derived predominantly from felsic volcanic rocks source.Geochemical data for these rocks suggest a continental island arc setting and continental active margin.Together with regional geological evidence,the sediments were deposited in a pull-apart basin.