Abstract:

 Tectonic setting and orientation of the provenance area of the Yanchang Fm remain unclear. To understand the tectonic property of the provenance area of this formation, this paper describes the sandstone petrologic characteristics, geochemical characteristics and distribution patterns of rare earth elements of Chang8 to Chang6 Member in Longdong area, Ordos Basin to determine the tectonic settings and diversity of provenance rocks in different areas. The results show that source rocks during Chang8 to Chang6 sedimentary period mainly came from volcanic arc source and transitional continental source associated with fold-thrusting, but source rocks of Chang7 and Chang6 in Huanxian and Yanwu, western basin were different from Chang8, part of which came from stable craton continental source. The REE abundance indicates that REE model was characterized by enrichment in light REE, depletion in heavy REE, and negative Eu anomaly. The provenance was involved with granitic crust materials which were characterized by containing more felsic rocks. Comparing samples from the northeast, northwest, southwest, and south Longdong area with various lithologies from ancient land surrounding the basin, this study shows that REE distribution patterns generally had the right-leaning

Key words: Provenance, Tectonic settings, REE distribution patterns, Yanchang Formation, Ordos Basin