Seismic Constraints on the Magmatic System Beneath the Changbaishan Volcano: Insight Into its Origin and Regional Tectonics

• Published in: Journal of geophysical research. Solid earth 2019-02, Vol.124 (2), p.2003-2024
• Main Authors: Fan, Xingli, Chen, Qi‐Fu
• Format: Article
• Language: English
• Subjects: Ambient noise; Anomalies; Asthenosphere; Changbai volcano; Decompression; Deformation mechanisms; Earth; Earth mantle; Earthquakes; Fossils; Geophysics; Instability; Lava; Magma; magma reservoir; Melting; Mesozoic; Ocean circulation; Oceans; Paleozoic; Resolution; S waves; Seismic activity; Seismic stability; Seismic velocities; Subduction; Subduction (geology); Surface water waves; surface wave tomography; Surface waves; suture zone; Tectonics; Tomography; Transition zone; Upper mantle; Upwelling; Velocity; Volcanic activity; Volcanic eruptions; Volcanism; Volcanoes; Wave velocity
• ISSN: 2169-9313; 2169-9356
• DOI: 10.1029/2018JB016288

There is a growing concern about the potential eruption of the Changbaishan volcano (CBV) in recent years, but the magmatic system beneath this volcano remains hotly debated. In this study, we construct a high‐resolution 3‐D crust and upper mantle S wave velocity (Vs) model beneath the CBV and adjacent regions combining ambient noise and earthquake surface wave tomography. Distinct low Vs anomalies are revealed in the crust and upper mantle beneath the CBV. The middle‐lower crustal low‐velocity body is interpreted to be the main magma chamber that may feed the surface volcanism and hydrothermal activities. The upper mantle low‐velocity zone is representative of upwelling asthenosphere. The lower crust beneath the Longgang volcano and Jingpohu volcano is also characterized by low Vs anomalies, maybe indicating low‐degree partial melting. We propose that the intraplate volcanism of the CBV as well as the Longgang volcano and Jingpohu volcano is driven by the decompression melting of upwelling asthenosphere, which could originate from the mantle transition zone as suggested by previous large‐scale tomographic studies. Moreover, the geologically identified Solonker‐Xar Moron‐Changchun‐Yanji suture zone is delineated by a prominent high Vs anomaly in the uppermost mantle, which may be explained by the fossil slab remnants or deformational fabrics resulted from the final closure of the Paleo‐Asian Ocean in the Late Paleozoic to Early Mesozoic. Plain Language Summary The concerns over the instability of the Changbaishan volcano located at the border between China and North Korea have drawn much public attention in recent years worldwide. However, the shallow detailed magmatic system underlying this volcano still remains hotly debated. Since seismic S wave velocity can be used as an indicator for existence of magma bodies in the Earth's interior, we constructed a 3‐D high‐resolution S wave velocity model in the Changbaishan volcano and adjacent regions by combining seismic ambient noise and earthquake surface wave tomography. We found that the S wave velocity beneath the Changbaishan volcano is significantly lower than the surrounding regions throughout the crust and upper mantle. Based on previous geophysical and geochemical investigations, our imaging results suggest that there might be a middle‐lower crustal magma chamber residing beneath the Changbaishan volcano, which is responsible for the surface volcanism and hydrothermal activities. This crustal magma cha