Department of Earth Sciences, Durham University, Durham DH1 3LE, UK.
Science. 2012 Apr 6;336(6077):72-5. doi: 10.1126/science.1214967.
Late accretion of primitive chondritic material to Earth, the Moon, and Mars, after core formation had ceased, can account for the absolute and relative abundances of highly siderophile elements (HSEs) in their silicate mantles. Here we show that smaller planetesimals also possess elevated HSE abundances in chondritic proportions. This demonstrates that late addition of chondritic material was a common feature of all differentiated planets and planetesimals, irrespective of when they accreted; occurring ≤5 to ≥150 million years after the formation of the solar system. Parent-body size played a role in producing variations in absolute HSE abundances among these bodies; however, the oxidation state of the body exerted the major control by influencing the extent to which late-accreted material was mixed into the silicate mantle rather than removed to the core.
原始球粒陨石物质在核心形成停止后，晚期添加到地球、月球和火星上，可以解释这些行星和小行星的硅酸盐幔中高亲铁元素（HSE）的绝对和相对丰度。在这里，我们表明较小的行星体也具有球粒陨石比例的升高的 HSE 丰度。这表明，无论何时形成，球粒陨石物质的晚期添加都是所有分化行星和小行星的共同特征；发生在太阳系形成后 ≤5 至 ≥150 百万年。母体大小在这些天体中产生绝对 HSE 丰度变化方面起了作用；但是，体的氧化状态通过影响晚期添加的物质混入硅酸盐幔的程度而不是被去除到核心来发挥主要控制作用。
