Intraplate volcanism controlled by back‐arc and continental structures in NE Asia inferred from transdimensional Bayesian ambient noise tomography

Abstract

Intraplate volcanism adjacent to active continental margins is not simply explained by plate tectonics or plume interaction. Recent volcanoes in northeast (NE) Asia, including NE China and the Korean Peninsula, are characterized by heterogeneous tectonic structures and geochemical compositions. Here we apply a transdimensional Bayesian tomography to estimate high‐resolution images of group and phase velocity variations (with periods between 8 and 70 s). The method provides robust estimations of velocity maps, and the reliability of results is tested through carefully designed synthetic recovery experiments. Our maps reveal two sublithospheric low‐velocity anomalies that connect back‐arc regions (in Japan and Ryukyu Trench) with current margins of continental lithosphere where the volcanoes are distributed. Combined with evidences from previous geochemical and geophysical studies, we argue that the volcanoes are related to the low‐velocity structures associated with back‐arc processes and preexisting continental lithosphere.

Intraplate Volcanism and Regional Geodynamics in NE Asia Revealed by Anisotropic Rayleigh‐Wave Tomography

“…At intermediate‐long periods (40–150 s) as shown in Figures d–i, the western part of our model is generally imaged with high‐velocity anomalies and the eastern counterpart generally shows low‐velocity features, similar to ambient noise tomography results (Kim et al, ; Zheng et al, ). Particularly, all the intraplate volcanoes appear to situate above or adjacent to abundant low‐velocity anomalies in the eastern part of our model.…”

“…The imaging results are well correlated with the surface geology, with thick sedimentary basins all displaying low‐velocity anomalies. The SW JI, where a group of island arc volcanoes develop, is imaged with pronounced low‐velocity anomaly, which is attributed to the partial melting occurring in the shallow mantle wedge above the subducting Pacific slab (e.g., Kim et al, ; Richards, ). The increase in the amplitude of anisotropy toward the northwest is widely influenced by the extensional tectonic history of back‐arc spreading in the continental rift zones that formed the large‐scale strike‐slip TLFZ and those extensional basins in EC and NEC (e.g., Ren et al, ; Schellart & Lister, ).…”

“…Map of NE Asia showing the main tectonic features. Red volcano symbols denote the Late Cenozoic intraplate volcanoes (with underlying subducting slab being completely absent or deeper than 300 km as defined in Kim et al, ): CBV = Changbaishan volcano; JPHV = Jingpohu volcano; LGV = Longgang volcano; XJDV = Xianjingdao volcano; CRV = Chuga‐Ryong volcano; ULV = Ulleung volcano; HLV = Halla volcano; FJV = Fukue‐jima volcano. Small red triangles show the locations of island arc volcanoes.…”

Seismic constraints on magma evolution beneath Mount Baekdu (Changbai) volcano from transdimensional Bayesian inversion of ambient noise data

“…PPDs of dispersion predicted from the resulting profiles for the MBV region (top; see also Figures 8a–8c) and the TLFZ region (bottom; see also Figures 8d–8f). (a, e) EGF group velocity dispersion and the observed data (gray circles and error bars), (b, f) EGF phase velocity dispersion and data (red circles and error bars), (c, g) RCS phase velocity dispersion and data (green circles and error bars), and (d, h) phase velocity dispersion and data (blue circles and error bars) from an independent study [ Kim et al ., ]. Insets show PPDs for the scaling parameter of each corresponding data set (with the corresponding color code).…”

“…Here we use four different surface wave dispersion data (curves) of Rayleigh wave fundamental mode, which are extracted from tomograms of (1) group velocities in the period range 5–20 s from the time domain method (Figure a), (2) phase velocities in the periods range 5–9 s from the time domain method (Figure b), (3) phase velocities in the period range 10–36 s from the spectral‐domain method (Figure b), and (4) phase velocities in the period range 38–50 s from Kim et al []. To better constrain deeper depths (> ~60 km), we additionally include this long period data, which are from ambient noise tomography for the broader area in northeast Asia [ Kim et al ., ]. The hierarchical transdimensional Bayesian method (see Appendix B for further details) provides a systematic way of joint inversions to combine four different data sets.…”