The magma system beneath Changbaishan-Tianchi Volcano, China/North Korea: Constraints from three-dimensional magnetotelluric imaging

Crust and Uppermost Mantle Magma Plumbing System Beneath Changbaishan Intraplate Volcano, China/North Korea, Revealed by Ambient Noise Adjoint Tomography

“…Our adjoint tomographic images, by substantially restoring the amplitudes and constraining the geometry of low velocity structures, clearly depict the magma ascending paths in the uppermost mantle region below the three volcanoes, which may serve to convey the deep-sourced mantle melts to shallow depths. Recent 3D MT studies conducted at CBV (Yang et al, 2021) and JPHV (Li et al, 2021) also revealed high conductivity features at corresponding depths, correlating well with the uppermost mantle low-velocities acquired in this study.…”

“…Our seismic images, together with previous geophysical observations (e.g., Hammond et al, 2020;Yang et al, 2021;Zhu et al, 2019) and geochemical examinations (e.g., Pan et al, 2017;Zhang et al, 2015), collectively imply a dynamic crust-mantle magma feeding system beneath CBV (Figure 4 and Movie S2 in the Supporting Information S1): The Pacific Plate subduction to the east induces buoyant upwelling of asthenospheric materials (Yang & Faccenda, 2020). The deep crust of CBV is intruded incrementally by basaltic flux generated within the upwelling asthenosphere via a narrow conduit, leading to the formation of a lower-crustal mush zone.…”

“…(2017) recently imaged a relatively high Vs at 20–40 km depth under CBV, which is invoked as evidence for solidified magmatic intrusions. However, this interpretation of cooled crustal structure with a low thermal state seems difficult to reconcile with other geophysical studies, most of which have identified zones of low density/resistivity/velocity, indicating the presence of partial melt and/or magma chamber(s) within the crust (e.g., Choi et al., 2013; Hammond et al., 2020; Yang et al., 2021; Zhang et al., 2002). On the other hand, although the crustal melt‐bearing region is widely believed to exist beneath CBV, its spatial location and lateral extent vary significantly in different studies (e.g., Fan & Chen, 2019; Zhu et al., 2019), likely due to various model resolutions and sensitivities of geophysical methods or caused by the limitation of data that mostly come from the Chinese side of this volcano (Chen et al., 2019).…”

“…The MT works (Qiu et al, 2014;Tang et al, 2001;Yang et al, 2021) and deep seismic sounding studies (Zhang et al, 2002) revealed high conductivities and low velocities in the crust and uppermost mantle beneath CBV. A cross-border receiver function analysis of Hammond et al (2020) suggested a lower-crustal magmatic system with its top at ∼6 km below CBV and extending ∼20 km laterally.…”

“…The lithospheric structures beneath CBV have been extensively studied via magnetotelluric (MT) surveys (Qiu et al., 2014; Tang et al., 2001; Yang et al., 2021), deep seismic soundings (Zhang et al., 2002), gravity modeling (Choi et al., 2013), receiver function analyses (Hammond et al., 2020; Ri et al., 2016; Wu et al., 2009), and surface wave tomography (Fan & Chen, 2019; Kim et al., 2017; Zhu et al., 2019). Despite much geophysical probing work, however, significant uncertainties still exist concerning the physical state and spatial distribution of the underlying magmatic system.…”