Nature and evolution of the Phanerozoic lithospheric mantle beneath the northwestern North China Craton: Evidence from peridotite xenolith

It is well-known that dramatic changes in composition and property of the lithospheric mantle have happened beneath the eastern part of the North China Craton (NCC) during the Phanerozoic, however, the nature and evolution of the lithospheric mantle beneath the western NCC is not well constrained because of the scarcity of peridotite xenolith in volcanic rocks in this region. This paper summarized all the available data on peridotite xenolith in Late Cretaceous-Cenozoic basalts to reveal the nature and transformation process of the lithospheric mantle beneath the northwestern NCC. The lithospheric mantle beneath this region was mainly composed of low-Mg-# lherzolites with minor high-Mg-# harzburgites. The high-Mg-# peridotites are the remnants of ancient refractory lithospheric mantle which experienced weakly refertilization. The low-Mg-# peridotites are likely produced through interaction between asthenospheric melts and high-Mg-# peridotites. They could be the result of refertilization of ancient refractory lithospheric mantle. The lithospheric mantle beneath the northwestern NCC underwent multiple modifications through mantle metasomatism involving subducted Paleo-Asian oceanic materials at early stage and basaltic melt deriving from asthenosphere recently. This comprehensive refertilization has a significant role in the transformation of ancient lithospheric mantle.