Water content in the early Cretaceous lithospheric mantle beneath the south-central Taihang Mountains: implications for the destruction of the North China Craton

Abstract

Based on studies of the water content of the early Cretaceous Feixian high-magnesium basalts in the eastern part of the North China Craton (NCC), it has been suggested that the early Cretaceous lithospheric mantle of the eastern NCC was highly hydrous (>1,000 ppm, H₂O wt.) and that this high water content had significantly reduced the viscosity of the lithospheric mantle and provided a prerequisite for the destruction of the NCC. The eastern part of the NCC had undergone multistage subduction of oceanic plates from the south, north, and east sides since the early Paleozoic, and these events may have caused the strong hydration of the NCC lithospheric mantle. To determine which subduction had contributed most to this hydration, we measured the water contents of the peridotite xenoliths hosted by the early Cretaceous high-magnesium diorites of Fushan in the south-central part of the Taihang Mountains. Our results demonstrate that the water content of the early Cretaceous lithospheric mantle beneath the south part of the Taihang Mountains was ~40 ppm and significantly lower than that of the contemporary lithospheric mantle beneath the eastern part of the NCC. Thus, the hydration of the early Cretaceous lithospheric mantle of the eastern part of the NCC can be ascribed to the subduction of the Pacific plate from the west side. Thus, the main dynamic factor in the destruction of the NCC was likely the subduction of the Pacific plate.