Seismic Structure of the Changbai Intraplate Volcano in NE China From Joint Inversion of Ambient Noise and Receiver Functions

Abstract

We study the detailed 3-D crustal and upper mantle structure beneath the active Changbai intraplate volcano in Northeast China by conducting a trans-dimensional Bayesian inversion of teleseismic receiver functions and Rayleigh-wave group velocity dispersions from ambient noise. More than 12,000 teleseismic receiver functions recorded at 78 seismic stations and 1,573 group velocity dispersions are used in this study. Receiver-function H-κ stacking measurements reveal a thick crust (~40 km) with a high Vp/Vs ratio (~1.8) beneath the Changbai volcano. Our joint inversion results show a heterogeneous crustal structure in the study region. A low-velocity body at depths of 8–15 km is revealed directly beneath the Changbai volcano, which has a lateral extent of ~100 km in the north–south direction and may reflect a large magma chamber in the midcrust. Our results also reveal a 5–10 km depressed Moho and a low-velocity anomaly in the uppermost mantle beneath the Changbai volcano. These features may indicate an upwelling channel of the asthenospheric material with a high mafic composition, and the mafic intrusion attaches to the bottom of the crust and thus deepens the Moho beneath the volcano. Our results support the notion that the Changbai volcanism is caused by hot and wet mantle upwelling associated with subduction-driven corner flow in the big mantle wedge above the stagnant Pacific slab in the mantle transition zone.