Zircon U-Pb Ages and Tectonic Implications of Late Paleozoic Volcanic Rocks in the Western Tianshan, North Xinjiang, China

The Late Paleozoic volcanic rocks are widespread in the Western Tianshan, and mainly consist of basalt, trachyte, trachy-andesite, andesite and rhyolite. However, the formation timing and tectonic implications of the volcanic rocks remain controversial. To obtain a comprehensive dataset with adequate spatial coverage, we collected the published zircon U-Pb age data of the Late Paleozoic volcanic rocks in the Western Tianshan, and mapped the temporal and spatial distribution of these volcanic rocks. Our compiled dataset indicates that the volcanic rocks in the Western Tianshan were formed in two major stages: Late Silurian-Early Carboniferous and Late Carboniferous-Middle Permian. The southward subduction of the Northern Tianshan Ocean formed a large number of Late Silurian-Early Carboniferous volcanic rocks. The flare-up of Late Carboniferous to Middle Permian magmatism in the NTOB was considered to be the response of the slab-roll back of the northern Tianshan Ocean. Therefore, arc magma assemblage and spatial-temporal distribution are of great significance to identify the dynamic mechanism transformation of subduction zone.