Abstract:The North Dabashan Mountain, an important part of the South Qinling orogenic belt, is well preserved sedimentary records. For a long time, the Banjiuguan Formation was considered to form in a relatively stable tectonic setting. In the paper, sedimentary successions and geochemical analyses are used to determine the provenance and tectonic setting. The Banjiuguan Formation consists of fine-grained sandstone, siltstone and mudstone deposited in deep water. Facies assemblages indicate that they were deposited in submarine fan. Paleocurrent data restored by cross bedding indicate that sediments are proximal derived from north. Chemical classification of Banjiuguan sandstones shows that the analyzed sediments are mostly litharenite. The REE patterns are characterized by LREE enrichment, flat HREE, and negative Eu anomalies. Chemical Index of Alteration range from 51 to 67, and Th/U ratio is 3.36 to 7.02, both of which suggest weak weathering. The rations of Zr/Sc and Th/Sc further show the sandstone experience no reworking. Various plots and parameters for sedimentary provenance show that the sediments were sourced predominantly from felsic rocks. Geochemical data suggest that they were formed in related to continental island arc setting and passive continental margin.