Distinct destruction mechanism in the North China Craton: Insight from high-resolution thermochemical structure

Despite numerous studies on the thinning and destruction of the lithospheric mantle root beneath the North China Craton (NCC), the mechanisms for modification from refractory mantle of ancient craton to the fertile one remains poorly understood due to insufficient information of deep thermochemical structure. We investigate the mantle compositional and thermal structure of the NCC by jointly inverting Rayleigh wave dispersion, geoid height, elevation and surface heat flow (SHF) using a probabilistic inversion. We image significant differences in the thermochemical structure of lithosphere in the different blocks of the NCC. The lithospheric structure of the western North China Craton (WNCC) is dominated by relatively thick lithospheric roots (>150 km) and depleted composition (Mg# ∼90–92), supporting the idea of the core of the WNCC is well-preserved. We observe a relatively thinner lithosphere (<100 km) and more fertile signature in the central and eastern NCC, confirming that these areas have undergone lithospheric thinning and modification. We reveal the distinct lithospheric composition in the central and eastern NCC, indicating the difference of mechanisms of lithospheric reactivation. The low Mg# (Mg# ∼88.5–90) of the lithospheric mantle beneath the eastern North China Craton (ENCC) imply that the cratonic root were delaminated and replaced by a new fertile mantle. The coexistence of depleted and fertile mantle (Mg# ∼88.5–91.5) beneath the central NCC, implying that the depleted cratonic mantle partially evolved to fertile one through injection of melts/fluids originating from the asthenospheric mantle.