Spatial and temporal evolution of lithospheric mantle beneath the eastern North China Craton: Constraints from mineral chemistry of peridotite xenoliths from the Miocene Qingyuan basalts and a regional synthesis

Mineralogical data are presented for the peridotite xenoliths from Miocene (~19Ma) Qingyuan basalts in the eastern North China Craton (NCC), with the aim of constraining on property of the sub-continental lithospheric mantle (SCLM) beneath the northern Tan-Lu Fault zone (TLFZ) during the Cenozoic. The Qingyuan peridotites are dominated by spinel lherzolites with moderate-Mg# olivines (89.4 to 91.2), suggesting that the regional SCLM is mainly transitional and fertile. Light rare earth element (LREE)-depleted, slightly depleted and enriched clinopyroxenes (Cpx) are identified in different peridotites. Chemical compositions of the LREE-enriched Cpx and the presence of phlogopite suggest that the Qingyuan SCLM has experienced silicate-related metasomatism. The synthesis of available mineral chemical data of the mantle xenoliths across the NCC confirms the SCLM beneath the NCC is highly heterogeneous in time and space. The Mesozoic-Cenozoic SCLM beneath the TLFZ and neighboring regions are more fertile and thinner than that beneath the region away from the fault zone. The fertile and refractory peridotite xenoliths experienced varying degrees of silicate and carbonatite metasomatism, respectively. The spatial-temporal lithospheric mantle heterogeneity in composition, age and thickness suggest that the trans-lithosphere fault zone played an important role in heterogeneous replacement of refractory cratonic lithospheric mantle.