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    地球上古老岩石的来源:基于太古宙岩石146Sm-142Nd同位素证据

    The Source of old terrestrial rocks:evidence from 146Sm-142Nd isotopes of Archean rocks

    • 摘要: 提要:通过构筑146Sm-142Nd同位素体质,应用于冥古宙(4.6~4.0Ga)时期地幔演化的研究,可以了解这一时期地幔演化过程。对太古宙岩石中的142Nd的研究发现早期地幔出现明显的不均一性,造成这种不均一的原因应该来源于地幔的分异作用。加拿大Nuvvuagittiug绿岩带来源于富集地幔和亏损地幔混合,但以富集地幔为主,格陵兰杂岩和变质砂岩来源于可以sun地幔,而西澳大利亚伊儿岗片麻岩来源于富集地幔和亏损地幔的混合带,但主要以亏损地幔为主。

       

      Abstract: Abstract:Through the construction of the 146Sm-142Nd system and the application of Hadean(4.6~4.0Gy)mantle evolution,we can get to know the evolutionary process of this early epoch. Based on the 142Nd study of Archean rocks,the authors hold that early mantle was an inhomogeneous system because of the mantle differentiation. Canadian Nuvvuagittug greenstone originated from the mixture of enriched and depleted mantle, with the enriched mantle playing the dominant role. Greenland mixtite and Isua metamorphosed sediments originated from depleted mantle whereas North Australian Yilgam gneiss origineted from the mixture of enriched and mantle, with the depleted mantle being dominant.

       

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