地幔再富集作用对岩石圈地幔Fe-Mg-Ca同位素组成的影响

Effects of Mantle Refertilization on Fe-Mg-Ca Isotopic Compositions of the Lithospheric Mantle

本文对目前的大洋玄武岩和华北地幔橄榄岩捕虏体的Fe-Mg-Ca同位素研究结果进行了系统的归纳和总结,并在此基础上,探讨地幔再富集作用对岩石圈地幔Fe-Mg-Ca同位素组成的影响,以期为进一步认识华北岩石圈地幔物质组成转变的方式提供新途径。统计结果表明,没有受到地幔交代作用影响的橄榄岩,其Fe-Mg-Ca同位素组成变化范围小,而地幔再富集作用会导致岩石圈地幔的Fe-Mg-Ca同位素组成明显不均一,说明地幔再富集作用是导致岩石圈地幔Fe-Mg-Ca同位素组成变化的重要机制。

In this paper,we have presented a systematic summary and overview of recent studies on Fe-Mg-Ca isotopic compositions of oceanic basalts in the world and mantle peridotitic xenoliths in basalts from the North China Craton,discussed effects of mantle refertilization on Fe-Mg-Ca isotopic compositions of the lithospheric mantle,in order to provide new ideas for further understanding the compositional transformation mode of the lithospheric mantle beneath the North China Craton. The statistic results show that the Fe-Mg-Ca isotopic compositions of peridotites which were no overprinted by the mantle metasomatism vary in a very small range,whereas those of the peridotites overprinted by the mantle refertilization are highly variable. These characteristics suggest that the mantle refertilization could significantly result in the modification of Fe-Mg-Ca isotopic compositions of the lithospheric mantle.