The short-lived Hf-W isotope system has a wide range of important applications in cosmochemistry and geochemistry. The siderophile behavior of W, combined with the lithophile nature of Hf, makes the system uniquely useful as a chronometer of planetary accretion and differentiation. Tungsten isotopic data for meteorites show that the parent bodies of some differentiated meteorites accreted within 1 million years after Solar System formation. Melting and differentiation on these bodies took ~1-3 million years and was fueled by decay of 26Al. The timescale for accretion and core formation increases with planetary mass and is ~10 million years for Mars and >34 million years for Earth. The nearly identical 182W compositions for the mantles of the Moon and Earth are difficult to explain in current models for the formation of the Moon. Terrestrial samples with ages spanning ~4 billion years reveal small 182W variations within the silicate Earth, demonstrating that traces of Earth's earliest formative period have been preserved throughout Earth's history.

中文翻译：

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行星中的钨同位素


短寿命Hf-W同位素系统在宇宙化学和地球化学中具有广泛的重要应用。 W 的亲铁行为与 Hf 的亲石性质相结合，使得该系统作为行星吸积和分化的计时器具有独特的用途。陨石的钨同位素数据表明，一些分化陨石的母体是在太阳系形成后一百万年内吸积的。这些天体的熔化和分化需要约 1-3 百万年的时间，并由 26Al 的衰变加速。吸积和核心形成的时间尺度随着行星质量的增加而增加，火星约为 1000 万年，地球约为 >34 万年。月球和地球地幔几乎相同的 182W 成分很难用当前的月球形成模型来解释。年龄跨度约 40 亿年的陆地样本揭示了硅酸盐地球内部 182W 的微小变化，这表明地球最早形成时期的痕迹在整个地球历史中一直被保留下来。