Mantle eclogite xenoliths are subducted oceanic crust fragments carried by host magma from the deep mantle.As a high-pressure metamorphic rock,mantle eclogite xenoliths may record important information about ancient oceanic crust,plate subduction and later metasomatic metamorphism.Therefore,their ages are particularly important.More than 500 published age results of mantle eclogite xenoliths in the world were selected,and several commonly used isotopic dating methods of mantle eclogite xenoliths were compared,and the advantages and disadvantages of different methods and their applicability were discussed.The results show that the rutile U-Pb,and Rb-Sr,Sm-Nd and Lu-Hf whole-rock isochron methods generally date the age of host magma or the time of mantle metasomatism;the sulfide Re-Os isochron age,zircon U-Pb age and the garnet-clinopyroxene isochron ages of Sm-Nd and Lu-Hf,as well as zircon Hf depleted-mantle model age,have a considerable prospect for the ages of protoliths and tectonic subduction;moreover,the peak of the oldest ages for mantle eclogite xenoliths mostly ranges from 3.1 Ga to 2.8 Ga,which coincides with the age of tectonic amalgamation of Kaapvaal and Siberian cratons.Therefore,it may represent the earliest formation age of mantle eclogite xenoliths,and also indicate that plate tectonics may have started in Mesoarchean.
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