An effective geochemical method to identify provenance from sources with similar geology: a case study from Ordos Basin, China

Abstract Rare earth elements, as the most resistant elements, have been widely used to determine sediment provenance. However, Yin Mountains and Qinling orogen, the two main source terrains of the Ordos Basin, both dominated by felsic rocks and experienced passive continental margin settings and active margin setting from the middle Proterozoic to the Tertiary. Without strongly contrasting geological settings, REEs distribution pattern alone and these related discrimination diagrams are inadequate to distinguish both. Nevertheless, the REEs abundance of mudstones solely supplied by each source terrain vary distinctly. Moreover, the total REEs contents of shales with the same provenance increase roughly with increasing CIA indices. Mudstones supplied by Yin mountains are significantly more enriched in REEs (average=309.4 ppm) but yield lower CIA indices (average=79.6), while those sourced from Qinling orogen yield lower REEs content (average=135.6 ppm) but higher CIA value (average=90.1). Considering the particular situation, we combine CIA with the total REE content (∑REEs) to provide new insights into sediment provenance identification and effectively distinguish the two source regions in Ordos Basin.