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6th International Archean Symposium
6th International Archean Symposium

Reactivation of craton margins: insight from seismic images

Oral

Talk Description

Characterized with positive buoyancy and high viscosity, Archean cratons are relatively flat, stable regions of the crust that have remained undeformed even though its margins may have suffered intermittent tectonic events. Inducing stress concentrations with strain localized at the boundaries, the margins help craton to avoid destruction. Therefore, the knowledge of reactivation of craton margins plays an important role in our understanding of craton evolution. The results from multidisciplinary studies, including geophysical, geological, and geochemical observations, suggest that the lithosphere of the North China Craton (NCC) has been extensively reactivated during the Late Mesozoic to Cenozoic. In contrast to the long-term stability of the western NCC, the eastern part has experienced a significant thinning from a thick (∼200 km) Archean or Proterozoic lithosphere to its currently ~80 km thick lithosphere. Almost all the boundaries of the NCC went through diverse deformations due to multiple-phases tectonic events surrounding it, including extensions and compressions. The NCC is therefore an ideal place to investigate the reactivation of craton lithosphere responding to different styles of tectonic tectonics. In this study, we revisit seismic datasets collected from portable arrays crossing the boundary between the eastern and western NCC. We implement a cutting-edge trans-dimensional Bayesian tomographic inversion technique to invert ambient noise dispersion and surface wave dispersion data for shallow lithospheric shear-wave velocity structure. By comparison of the interior structures across the boundary, we discuss the reactivation of craton margins in responses to compression and extension deformations exerted by the mantle flow triggered by the Pacific Plate subduction, and its implications for the secular change in the rheology of craton lithosphere.

Speakers