Widespread refertilization of cratonic lithospheric mantle related to circum-craton plate subduction: evidence from peridotite xenoliths from the central North China Craton.

Subduction of the Pacific slab has been widely credited for the destruction of the eastern North China Craton (NCC). However, the nature of the subcontinental lithospheric mantle (SCLM) beneath the central and western NCC is less well constrained, which has hindered the understanding of cratonic responses to repeated Phanerozoic circum-craton subductions. Here, we report the in situ major- and trace-element contents and Sr isotopic compositions of minerals from 27 peridotite xenoliths obtained from Cenozoic basalts from Xiyang‒Pingding, central NCC, to gain new insights into how plate subduction affected the Archean lithospheric keel. On the basis of olivine major-element and clinopyroxene trace-element contents, as well as clinopyroxene Sr isotopic compositions, we divide the xenoliths into four types. The high-Mg# types 1 and 2 peridotites show high olivine forsterite (Fo) contents, convex-upward rare-earth element patterns, and high ⁸⁷Sr/⁸⁶Sr (0.7053‒0.7062) in clinopyroxene, and they could be relicts of an old cratonic root. The high-Mg# type 3 peridotites exhibit high (La/Yb)_N and low Ti/Eu and ⁸⁷Sr/⁸⁶Sr (0.7038‒0.7044), and they are interpreted as reaction products of Archean SCLM and carbonatitic melts from the asthenosphere with a contribution of recycled oceanic components. The low-Mg# type 4 peridotites display low ⁸⁷Sr/⁸⁶Sr (0.7029‒0.7033) and represent fragments of modified SCLM that has been recently refertilized by asthenospheric melts. Complex architectures of the SCLM underneath Xiyang‒Pingding reflect multistage overprinting of mantle metasomatism. Recent influxes of asthenospheric melts played a critical role in transforming refractory SCLM to fertile SCLM. Combined with previous studies, our findings suggest that the SCLM beneath the central NCC became progressively more refertilized from the center toward both the northern and southern margins, a spatial pattern that was likely generated by N‒S-trending subductions of the circum-craton plates. [ABSTRACT FROM AUTHOR]