Tilting‐Axis Anisotropic Tomography and Subduction Dynamics of the Java‐Banda Arc

Abstract

AbstractThe 180° curvature of the Banda arc at the eastern end of the Java‐Banda subduction zone reflects complicated geodynamic processes. A detailed investigation of its anisotropic structure would reveal its subduction dynamics, further resolving the controversial issue on how the highly arcuate Banda arc formed. We apply tilting‐axis anisotropic tomography to obtain a high‐resolution 3‐D anisotropic model beneath the Java‐Banda region. Our results show significant differences between Java and Banda in the pattern of anisotropy in both the subducting slab and its surrounding mantle, which reflect two distinctly different deformation modes in the two domains. Our results support the single‐slab subduction model for the Banda region. In addition, trench‐normal and upright fast‐velocity‐planes appear in the deep upper mantle, which may indicate material migrations in the big mantle wedge. Fast‐velocity‐planes in the shallow mantle exhibit a toroidal distribution, reflecting past counter‐clockwise rotation and asthenospheric material extrusion.