Bennett Vickie C, Brandon Alan D, Nutman Allen P
Research School of Earth Sciences, Australian National University, Canberra ACT, 0200 Australia.
Science. 2007 Dec 21;318(5858):1907-10. doi: 10.1126/science.1145928.
The oldest rocks-3.85 billion years old-from southwest Greenland have coupled neodymium-142 excesses (from decay of now-extinct samarium-146; half-life, 103 million years) and neodymium-143 excesses (from decay of samarium-147; half-life, 106 billion years), relative to chondritic meteorites, that directly date the formation of chemically distinct silicate reservoirs in the first 30 million to 75 million years of Earth history. The differences in 142Nd signatures of coeval rocks from the two most extensive crustal relicts more than 3.6 billion years old, in Western Australia and southwest Greenland, reveal early-formed large-scale chemical heterogeneities in Earth's mantle that persisted for at least the first billion years of Earth history. Temporal variations in 142Nd signatures track the subsequent incomplete remixing of very-early-formed mantle chemical domains.
来自格陵兰西南部的最古老岩石（距今38.5亿年），相对于球粒陨石，具有耦合的钕 - 142过剩（源自现已灭绝的钐 - 146衰变；半衰期为1.03亿年）和钕 - 143过剩（源自钐 - 147衰变；半衰期为1060亿年），这直接确定了地球历史最初3000万至7500万年中化学性质不同的硅酸盐储库的形成时间。来自西澳大利亚和格陵兰西南部的两块超过36亿年历史的最广泛地壳遗迹中同时期岩石的钕 - 142特征差异，揭示了地球地幔中早期形成的大规模化学不均一性，这种不均一性在地球历史的至少最初十亿年中持续存在。钕 - 142特征的时间变化追踪了极早期形成的地幔化学域随后的不完全再混合情况。
