A Mid-Late Permian transition from oceanic subduction to continental collision in the northern margin of the North China Craton (NE China)

Abstract

The tectonic evolution of the northern margin of the North China Craton (NCC) remains controversial. In this study, we present zircon U-Pb ages, geochemistry, and Sr-Nd isotope data of andesites and dacites, and detrital zircon ages of siltstones from the Woguadi Formation in central Jilin Province, Northeast China. Dating of volcanic rocks from the Woguadi Formation yielded weighted mean ages ranging from 271 Ma to 256 Ma. The andesites are characterized by high Sr (635–746 ppm) and low Y (14.5–15.9 ppm) and Yb (1.41–1.51 ppm) contents, exhibiting geochemical affinities to adakites. Melts generated from partial melting of subducted oceanic crust interacted with peridotite during their ascent through the mantle wedge, most likely forming these andesites. The dacites show relatively low Sr (123–273 ppm) and high Y (14.7–29.4 ppm) and Yb (1.57–3.09 ppm) contents, displaying geochemical affinities to arc. These dacites formed from partial melting of crust metasomatized by fluids, sedimentary melts and mantle components, as supported by isotopic compositions (initial ⁸⁷Sr/⁸⁶Sr ratios of 0.7029–0.7044 and ε_Nd(t) values of 2.22–3.02). The volcanic rocks formed in an active continental margin related to southward subduction of the Paleo-Asian Ocean (PAO) during the Mid-Late Permian. Detrital zircons from the siltstones were mainly sourced from the NCC. The crustal thickness estimated by whole-rock trace elements and detrital zircon Eu/Eu* ratios suggests that the subduction initiation of the PAO occurred at ca. 330 Ma and the NCC and neighboring arcs began to collide at ca. 270 Ma.