The Qingshan mafic rocks exhibit geochemical characteristics distinct from those of mantle peridotite- or pyroxenite-derived melt as well as from Fangcheng basalts, the only basalts documented in the Cretaceous volcanic suites in Shandong province. They are inferred to be crust-derived melts. However, a clear decreasing trend in ACNK with Mg# increasing and the elevated MgO, Cr and Ni contents relative to basalt-derived melts indicate assimilation with mantle peridotite during their pristine magmatic evolution. Such a two-step process can be best explained by the Archean lower crust delamination of the North China craton with a ~35 % partial melting followed by a variable extent of metasomatic interaction with convecting mantle peridotite, which thus resulted in the low-Mg and high-Mg andesitic suites. Nd–Sr isotopic and HFSE features imply that the convecting mantle was mixed with the foundered lithospheric peridotite, which previously experienced subduction-related melt metasomatism during the collision of the Yangtze-North China cratons in the early Triassic. The Qingshan volcanic suites in western Shandong are synchronous with the Tan-Lu strike-slip fault, inferring that the lower crust delamination was initially triggered by sinistral motion of the Tan-Lu fault at ~130 Ma. Due to an eastward development of regional lithospheric delamination, the Jiaozhou bimodal volcanic succession was formed owing to the regional geothermal gradient increase and lithosphere thinning. The recognition of contrasting andesitic suites in the Qingshan volcanic succession and their temporal trend provide additional evidence for lower crust delamination during the early Cretaceous in the North China craton and new constraints on its lithosphere thinning model.