Abstract

Detailed knowledge of lithospheric structure is essential for understanding the long-term evolution and dynamics of continents. We present an image of lithospheric structure across the central and western North China Craton (NCC), derived using S and P receiver functions from a dense seismic array. A negative velocity discontinuity is identified at ∼80–100 km depth within the thick lithosphere (∼160–200 km), similar to that observed in many other cratonic regions and roughly at the same depth as the base of the lithosphere in the eastern NCC. The intralithospheric discontinuity may indicate an ancient, mechanically weak layer within the overall strong cratonic lithosphere, and probably also existed beneath the eastern NCC before the Mesozoic. The presence of such a weak layer could have facilitated simultaneous lithospheric modification at the base and the middle of the lithosphere in the eastern NCC, especially under the strong influence of the Mesozoic Pacific subduction, leading to the severe lithospheric thinning and destruction recorded in this region. The weak layer probably did not strongly affect the stability and evolution of the central and western NCC and other cratonic regions where effects from plate boundary processes were weak. Our seismic images, integrated with geological data, provide new insights into structural heterogeneities in the subcontinental lithospheric mantle and their roles in the dynamic evolution of continents.

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