TY - JOUR
T1 - Backarc spreading and mantle wedge flow beneath the Japan Sea
T2 - Insight from Rayleigh-wave anisotropic tomography
AU - Liu, Xin
AU - Zhao, Dapeng
N1 - Funding Information:
ACKNOWLEDGEMENTS We thank the data center of the F-net broadband seismic network (www.fnet.bosai.go.jp) for providing the high-quality waveform data used in this study. The free software GMT (Wessel and Smith 1998) is used for making the figures.We appreciate the helpful discussions with Drs G. Jiang, S. Xia, J. Wang, W. Wei, Z. Huang, C. Chen, K. Yoshizawa and S. Zhao. We are very grateful to Prof M. Ritzwoller (the Editor), Prof D. Forsyth and Prof M. Pasyanos who provided thoughtful review comments and suggestions which have greatly improved this paper. This work was supported by grants from the JSPS (Kiban-S 23224012) and the MEXT (26106005) to D. Zhao, grants from Chinese NSFC (41190072 and 41325009), the China Postdoctoral Science Foundation (2014M551957), the Shandong Provincial Natural Science Foundation, China (BS2015HZ001) and the Fundamental Research Funds for the Central Universities (201513058) to X. Liu.
Publisher Copyright:
© The Authors 2016.
PY - 2016/10/1
Y1 - 2016/10/1
N2 - We present the first high-resolution Rayleigh-wave phase-velocity azimuthal anisotropy tomography of the Japan subduction zone at periods of 20-150 s, which is determined using a large number of high-quality amplitude and phase data of teleseismic fundamental-mode Rayleigh waves. The obtained 2-D anisotropic phase-velocity models are then inverted for a 3-D shear-wave velocity azimuthal anisotropy tomography down to a depth of ~300 km beneath Japan. The subducting Pacific slab is imaged as a dipping high-velocity zone with trench-parallel fast-velocity directions (FVDs) which may indicate the anisotropy arising from the normal faults produced at the outer-rise area near the Japan trench axis, overprinting the slab fossil fabric, whereas the mantle wedge generally exhibits lower velocities with trenchnormal FVDs which reflect subduction-driven corner flow and anisotropy. Depth variations of azimuthal anisotropy are revealed in the big mantle wedge beneath the Japan Sea, which may reflect past deformations in the Eurasian lithosphere related to backarc spreading during 21 to 15 Ma and complex current convection in the asthenosphere induced by active subductions of both the Pacific and Philippine Sea plates.
AB - We present the first high-resolution Rayleigh-wave phase-velocity azimuthal anisotropy tomography of the Japan subduction zone at periods of 20-150 s, which is determined using a large number of high-quality amplitude and phase data of teleseismic fundamental-mode Rayleigh waves. The obtained 2-D anisotropic phase-velocity models are then inverted for a 3-D shear-wave velocity azimuthal anisotropy tomography down to a depth of ~300 km beneath Japan. The subducting Pacific slab is imaged as a dipping high-velocity zone with trench-parallel fast-velocity directions (FVDs) which may indicate the anisotropy arising from the normal faults produced at the outer-rise area near the Japan trench axis, overprinting the slab fossil fabric, whereas the mantle wedge generally exhibits lower velocities with trenchnormal FVDs which reflect subduction-driven corner flow and anisotropy. Depth variations of azimuthal anisotropy are revealed in the big mantle wedge beneath the Japan Sea, which may reflect past deformations in the Eurasian lithosphere related to backarc spreading during 21 to 15 Ma and complex current convection in the asthenosphere induced by active subductions of both the Pacific and Philippine Sea plates.
KW - Backarc basin processes
KW - Seismic anisotropy
KW - Seismic tomography
KW - Subduction zone processes
KW - Surface waves and free oscillations
UR - http://www.scopus.com/inward/record.url?scp=84988731407&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=84988731407&partnerID=8YFLogxK
U2 - 10.1093/gji/ggw288
DO - 10.1093/gji/ggw288
M3 - Article
AN - SCOPUS:84988731407
VL - 207
SP - 357
EP - 373
JO - Geophysical Journal International
JF - Geophysical Journal International
SN - 0956-540X
IS - 1
ER -