Cenozoic destruction of eastern North China Craton evidenced by seismically imaged lithosphere delamination and Nd isotopes

<p>The North China Craton (NCC), once stable during the Precambrian, lost its stable craton characteristics in the Mesozoic. However, its post-Mesozoic evolution remains poorly constrained. Here, we have determined a high-resolution velocity model of the NCC lithosphere by joint inversion of body wave arrival times, surface wave dispersion data and receiver functions. Our velocity model reveals pronounced lithospheric thinning in the eastern NCC (~60–70 km), contrasting with the ~120 km-thick lithosphere beneath the western NCC (primarily the Ordos Basin). Beneath the North-South Gravity Lineament (NSGL), there is a tunnel-shaped low velocity zone apexing near the Moho, suggesting complete destruction and metasomatic replacement of the original lithospheric mantle in this region. Several high-velocity bodies imaged at below ~80-90 km depth in the eastern NCC are interpreted as delaminated lithospheric fragments. Combining their depths with geochemical constraints, we propose these delamination events most likely occurred during the Cenozoic. The delaminated bodies are spatially consistent with the elevated heat flow patterns, consistent with delamination-driven upwelling of hot asthenospheric material. Furthermore, our model indicates ongoing destabilization along the eastern margin of the Ordos Basin lithosphere, likely induced by sustained westward mantle flow. Geochemical evidence from Cenozoic magmatic rocks, marked by both positive and negative εNd(t), implies that Cenozoic lithospheric modification in the eastern NCC was jointly controlled by asthenospheric convection (linked to Pacific Plate subduction) and episodic lithospheric delamination. These findings demonstrate that the NCC’s lithosphere has experienced prolonged, multi-stage destruction extending into the Cenozoic.</p>