华北克拉通西北部显生宙岩石圈地幔属性与演化特征: 橄榄岩捕虏体证据

众所周知，华北克拉通东部岩石圈地幔的组成和性质在显生宙发生了显著变化，但由于西部出露含有捕虏体的火山岩较少，这在一定程度上限制了人们对该区岩石圈地幔属性与演化特征的认识。本文将华北克拉通西北部晚白垩世-新生代玄武岩中橄榄岩捕虏体的研究成果归纳总结，旨在进一步揭示该区岩石圈地幔的属性与演化特征。研究表明，华北克拉通西北部岩石圈地幔主要由低Mg^#的二辉橄榄岩和少量高Mg^#的方辉橄榄岩组成。高Mg^#橄榄岩代表该区受轻微再富集作用影响的古老岩石圈地幔残余，低Mg^#橄榄岩是软流圈来源熔体与高Mg^#橄榄岩反应的产物，代表地幔再富集作用对古老岩石圈地幔改造的结果。该区岩石圈地幔经历了多期地幔交代作用的改造，早期交代事件与古亚洲洋俯冲有关，近期与软流圈来源的玄武质熔体有关。这种广泛的地幔再富集作用对华北克拉通古老岩石圈地幔的转变做出了重要贡献。

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.