Yin Qingzhu, Jacobsen S B, Yamashita K, Blichert-Toft J, Télouk P, Albarède F
Department of Earth and Planetary Sciences, Harvard University, 20 Oxford Street, Cambridge, Massachusetts 02138, USA.
Nature. 2002 Aug 29;418(6901):949-52. doi: 10.1038/nature00995.
Determining the chronology for the assembly of planetary bodies in the early Solar System is essential for a complete understanding of star- and planet-formation processes. Various radionuclide chronometers (applied to meteorites) have been used to determine that basaltic lava flows on the surface of the asteroid Vesta formed within 3 million years (3 Myr) of the origin of the Solar System. Such rapid formation is broadly consistent with astronomical observations of young stellar objects, which suggest that formation of planetary systems occurs within a few million years after star formation. Some hafnium-tungsten isotope data, however, require that Vesta formed later (approximately 16 Myr after the formation of the Solar System) and that the formation of the terrestrial planets took a much longer time (62(-14)(+4504) Myr). Here we report measurements of tungsten isotope compositions and hafnium-tungsten ratios of several meteorites. Our measurements indicate that, contrary to previous results, the bulk of metal-silicate separation in the Solar System was completed within <30 Myr. These results are completely consistent with other evidence for rapid planetary formation, and are also in agreement with dynamic accretion models that predict a relatively short time (approximately 10 Myr) for the main growth stage of terrestrial planet formation.
确定早期太阳系中行星体聚集的时间顺序对于全面理解恒星和行星形成过程至关重要。各种放射性核素计时仪（应用于陨石）已被用于确定小行星灶神星表面的玄武岩熔岩流是在太阳系形成后的300万年（3 Myr）内形成的。这种快速形成与对年轻恒星天体的天文观测大致一致，这些观测表明行星系统的形成发生在恒星形成后的几百万年内。然而，一些铪-钨同位素数据表明灶神星形成得更晚（大约在太阳系形成后16 Myr），并且类地行星的形成花费了更长的时间（62（-14）（+4504）Myr）。在此，我们报告了几种陨石的钨同位素组成和铪-钨比率的测量结果。我们的测量表明，与之前的结果相反，太阳系中大部分金属-硅酸盐分离在<30 Myr内完成。这些结果与行星快速形成的其他证据完全一致，也与预测类地行星形成主要增长阶段相对较短时间（约10 Myr）的动态吸积模型相符。
