We found a match
Your institution may have access to this item. Find your institution then sign in to continue.
- Title
Upper Mantle Structure Beneath Mariana: Insights From Rayleigh-Wave Anisotropic Tomography.
- Authors
Qingyu Qiao; Xin Liu; Dapeng Zhao; Sanzhong Li; Shujuan Zhao; Long Zhao; Xiao Wang
- Abstract
We determine Rayleigh-wave phase-velocity azimuthal anisotropy tomography beneath Mariana using a large number of high-quality amplitude and phase data of teleseismic fundamental mode Rayleigh waves at periods of 25-130 s. The obtained phase-velocity model is then inverted for a 3D azimuthal anisotropic shear-wave velocity (Vs) model down to ~300 km depth. The old (~150 Ma) Pacific oceanic lithosphere near the Mariana trench is imaged as a clear high-Vs zone with a thickness of ~100 km, whereas obvious low-Vs anomalies exist in the mantle wedge and in the asthenosphere beneath the incoming plate. The Pacific oceanic lithosphere near the Mariana trench mainly exhibits a fast-velocity direction (FVD) of NW-SE normal to seafloor isochrons, which may reflect frozen-in lattice-preferred orientation formed at the mid-ocean ridge, whereas the dominant FVD in the subducting Pacific slab at depths >~100 km is parallel to the Mariana trench, probably reflecting subduction-related structural deformation in the slab. Significant trench-normal FVDs exist in the mantle wedge at depths <~100 km, whereas the deeper portion of the mantle wedge mainly exhibits trench-parallel FVDs, which may indicate a flow pattern in the mantle wedge due to the slab deep subduction and dehydration.
- Subjects
ANISOTROPY; TOMOGRAPHY; RAYLEIGH waves; LITHOSPHERE; VELOCITY
- Publication
Geochemistry, Geophysics, Geosystems: G3, 2021, Vol 22, Issue 11, p1
- ISSN
1525-2027
- Publication type
Article
- DOI
10.1029/2021GC009902