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Abstract

In Eastern China, complex tectonic structures of high geological/geophysical relevance suggest multiple subductions in the region making the region an ideal physical laboratory for investigating the feedback effect of subduction on the continent. In particular, subduction could have resulted in the formation of the Tan-Lu Fault Zone (TLFZ); a tectonic structure believed to have significantly aided the instability of the lithosphere and as well, played an essential role in the further modification of the lithosphere. To provide additional observational constraints on the fault activities such as its affinity to regional deformation, we took advantage of the ambient noise dataset to produce joint tomography models of Vsv (isotropic and azimuthal anisotropy) across the TLFZ. First, the models reveal structural segmentation, with structures that trend in the direction of the strike of the TLFZ. The isotropic Vsv shows a widespread low velocity in the lower crust, which could serve as a stress accumulator for the reactivation of faults. The polarization of azimuthal anisotropy in the TLFZ and the Zhangbaling uplift are NNE-SSW to N-S; sub-parallel to the strike of the fault in the crust and uppermost mantle. The trend of the anisotropy mimics the shape of the TLFZ in the crust and the uppermost mantle, which confirms that the Tan-Lu fault is a deep-seated lithospheric structure. This may also suggest that the fault controls the anisotropy and hence, the deformation in the region. These models highlight the dominant control of the fault on the regional deformation and geodynamic processes in eastern China.