Chronological evidence of Neoproterozoic volcanic rocks in the eastern segment of the North Qilian Mountains

Abstract: According to the geological survey of 1:50000 Shimenchuan Sheet and Laolongwan Sheet, volcanic rocks different from those in the Early Ordovician Yingou Goup have been found in the Shandiaodiaopo area, Jingtai County in the eastern segment of the North Qilian Mountains. Sm-Nd isochron dating of the volcanic rocks shows that they formed during the Neoproterozoic, about 723 million years ago. REE and trace element and trace element geochemical characteristics suggest that a compressional environment resulting from subduction of oceanic crust occurred there at that time.