Redefinition of the "Longshoushan Group" outcropped in the eastern segment of Longshoushan on the southern margin of Alxa Block: Evidence from detrital zircon U-Pb dating results

A suite of low-grade metamorphic sedimentary rocks,exposed in Huashikoujing area of eastern Longshoushan,was originally regarded as the Paleoproterozoic Longshoushan Group.Detrital zircons from two low-grade metamorphic sedimentary rocks yielded ages ranging from 0.52 Ga to 3.56 Ga,similar to the age spectrum of the rock from neighboring Cambrian Dahuangshan Group.Thus,the metamorphic sedimentary rocks were probably deposited in the middle-late...