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系统介绍了地核的形成时间、地核的物理特性、化学成分和物质存在相态。利用W-Hf同位素系测年方法厘定地核与地幔分异的年龄是在地球形成的最初30 Ma。但是,内核的结晶年龄还是未知的。地核声波速度的各向异性可能是六面体紧密堆积(hcp)相铁的c轴方向沿地球轴线优选定向排列引起的。利用地球物理资料估算的地核密度与响应温压条件下液态铁的密度差值是5%~10%,因此,判断主要是铁镍合金的地核应该含有一定量的比铁轻的元素,如碳、硫、磷、硅、氧、氢以及其他轻元素。这些轻元素对D″的形成、地幔柱的形成、演化以及地震、火山活动的影响应该是值得探索的新领域。
The system introduces the formation time of the core, the physical characteristics of the core, the chemical composition and the phase existence of the material. The W-Hf isotopic dating method determined the age of the core-mantle divergence in the first 30 Ma of Earth’s formation. However, the crystallization of the kernel is still unknown age. The anisotropy of the acoustic velocity at the nuclei may be caused by the preferred orientation of the c-axis of hexagonal close-packed iron along the earth’s axis. The difference between the density of the earth core estimated by the geophysical data and the density of the liquid iron under the condition of the temperature and pressure is 5% -10%. Therefore, judging that the core of the iron-nickel alloy mainly contains a certain amount of elements lighter than iron, Such as carbon, sulfur, phosphorus, silicon, oxygen, hydrogen and other light elements. The impact of these light elements on the formation of D ", the formation and evolution of mantle plumes, and the earthquakes and volcanic activities should be new areas worth exploring.