A review on lithospheric structures of Chinese mainland

The formation of the Chinese mainland has been a result of the amalgamation of multiple blocks over an extended geological history. The lithospheric structures of these different blocks exhibit significant variations, and their interactions have been intense, leading to the fundamental characteristics of active geological tectonics and severe geological hazards in present-day China. Since the beginning of this century, seismology has developed rapidly, revealing high-precision crustal and upper mantle structures. This paper summarizes the latest progress in seismological studies regarding the depths of the Moho and the lithosphere-asthenosphere boundary (LAB) in the Chinese mainland, constructing a fundamental framework for the lithosphere at a first-order scale. Overall, the crust of the Qinghai-Xizang Plateau is the thickest, reaching up to more than 70 km, while the crust in eastern China is the thinnest, averaging around 30 km. However, improvement is necessary particularly in understanding small-scale structures. On one hand, the crustal thickness derived from natural earthquakes is generally smaller than that obtained from artificial seismic sources, which may reflect the complex nature of the Moho. On the other hand, the lateral variations in crustal structure near major tectonic boundaries or fault zones are significant, arguing for dense seismic array observations and research in key areas to better study block interactions. Research on lithospheric thickness remains relatively limited, with reliable results obtained only along certain profiles, and there are notable discrepancies between seismic wave velocity structures and thermal lithospheric structures. Future efforts are required in both data acquisition and methodological advancements. Building on one-dimensional lithospheric layer structures, future research should focus on revealing high-precision three-dimensional lithospheric structures to better constrain the rheological properties and deformation characteristics of the Chinese mainland lithosphere. This will facilitate the exploration of important scientific issues related to the geodynamic evolution of the Chinese mainland.