Rare earth element characteristics of sediment samples of Triassic maximum flooding period in Longdong area of Ordos Basin and their provenance significance

The period of Chang 7 deposition in Upper Triassic was the maximum flooding period of Ordos Basin. Rare earth elements(REE) analyses of rock samples from the study area and around the basin show that the REE characteristics of mudstone samples of the study area is similar to the characteristics of UCC, and the REE patterns are basically the same as the patterns of ancient granite and metamorphic rocks around the basin, except for the ancient granite of Luliang Mountains in the east region. The experimental results demonstrate that the sediments of the study area were derived from UCC, with the main composition being felsic rock. All old lands around the basin provided sediments except Luliang Mountains, which were not uplifted at that time.