Geochemistry and geochronology of basic igneous rocks in Bairin Right banner, southeastern inner Mongolia, China: Implications for the final closure of the Paleo—Asian Ocean along the Xar Moron suture zone

This paper reports the first discovery of basic igneous rocks in Bairin Right Banner southeastern Inner Mongolia, China. To understand genesis and tectonic evolution these rocks, we have carried out geochronology geochemistry research on them. The results show that LA-ICP-MS zircon U-Pb concordant mean ages massive basalt, diabase, pillow basalt are 272.0 ± 2.8 Ma, 261.5 3.2 256.5 2.5 respectively, suggesting their formation during Late Permian. tholeiitic with low Mg # values ranges 46.2–66.8, 54.4–71.0, 53.5–58.2, respectively. They similar chondrite-normalized rare earth element (REE) patterns. intensity REE differentiation is to typical enriched mid-ocean ridge basalts (E-MORB). relatively Ba U, while slightly depleted Rb Th, geochemical affinity E-MORB. diabases same primitive mantle-normalized patterns Rb, Ba, Nb Ta, island arc magmas. Our new findings indicate intra-oceanic subduction Paleo-Asian Oceanic slab was still ongoing late Permian area and, combined previous studies, it might been closed Early Triassic along Xar Moron suture zone.