Study of teleseismic P-wave attenuation beneath the Nuomin River Volcanoes

Intraplate volcanism is a key access to the deep architecture beneath intra-continental. NE China is a worthy experimental site for exploring intraplate volcanism, where abundant Cenozoic volcanic sites are mainly distributed along the Da Hinggan and surrounding the Songliao Basin. Since volcanoes located at the Da Hinggan are lack of geophysical observations, this study is focused on the Nuomin River Volcanic site sitting on the northern Da Hinggan. We estimated the Δt* value of 300 P-wave phases from 17 teleseismic events received by 43 seismometers deployed around the Nuomin River Volcanoes, using a time-domain waveform matching method. Furthermore, we obtained a 2D map of Δt* by applying a non-linear Bayesian Monte Carlo inversion. The observed relative attenuation facilitated our comprehensive understanding of the deep structure beneath the Nuomin River Volcanoes. Results suggest that highly attenuated regions are consistent well with the locations of volcanism. Higher Δt* values are observed beneath the Nuomin River Volcanoes and the northern region near the Xiaoguli River Volcano to the north, where hot mantle upwelling are inferred. Lower attenuation is found to the east of the Nuomin River Volcanic site, where reduction of Δt* is up to ~0.3±0.05 s when comparing with the highest observation. We attribute these low Δt* observations to two main causes: the remained thicker lithosphere and the presence of partial melting and consequent mantle dehydration beneath this region. © 2021, Science Press. All right reserved.