Transformation of Subcontinental Lithospheric Mantle through Peridotite-Melt Reaction:Evidence from a Highly Fertile Mantle Xenolith from the North China Craton
作者单位：The Pheasant Memorial Laboratory for Geochemistry and Cosmochemistry Institute for Study of the Earth’s InteriorOkayama University at MisasaTottori 682-0193Japan
会议名称：《中国科学院地质与地球物理研究所2007学术年会》
会议日期：2008年
学科分类：0709[理学-地质学] 070901[理学-矿物学、岩石学、矿床学] 07[理学]
基 金：supported by the Chinese Academy of Sciences(KZCX2-YW-103) the Natural Science Foundation of China (40534022 and 40523003 to H.Zhang) the Program of Center of Excellence for the 21st Century in Japan(to E.Nakamura)
摘 要：A highly fertile mantle xenolith entrained in the Upper Cretaceous Daxizhuang basalt,Shandong Province,China provides petrological evidence for reaction between basaltic melt and refractory peridotite in Mesozoic lithospheric mantle beneath the eastern North China *** xenolith is zoned with a Iherzolite core,a sheared wehriite mande,and a reaclant *** Iherzolite has a medium-grained granular texture and contains olivine,orthopyroxene,clinopyroxene,and spinel with low Mg# values(≤87).This is the lowest value observed globally in mantle xenoliths entrained in both kimberlites and basalts from old cratons,but is close to low-Mg# spinel lherzolites entrained in adjacent region of the eastern North China *** wehriite mantle shows clear orientation and foliation of constituent olivine and *** reactant rim displays a symplectite texture of fine-grained olivine,clinopyroxene,and spinel,and is characterized by LREE-enriched *** is lacking from the sheared mantle and reactant *** zoning and systematic core-rim variations in major and trace elements of the constituent minerals demonstrate the occurrence of the refertilization through the melt-peridotite reaction in the *** reaction may have produced the low-Mg# peridotite from a high-Mg# protolith and could be an important mechanism for the change of the subcontinental lithospheric mantle from a Paleozoic refractory mantle to a Late Mesozoic fertile mantle.