Source regions and timescales for the delivery of water to the Earth
Source regions and timescales for the delivery of water to the Earth
复制标题
DOI：
10.1111/j.1945-5100.2000.tb01518.x
复制
发表时间：
2000-11-01
影响因子：
2.2
通讯作者：
Cyr, KE
中科院分区：
文献类型：
--
作者：
Morbidelli, A;Chambers, J;Cyr, KE
在原始太阳系中，地球吸积水最可能的来源是外小行星带、巨行星区域和柯伊伯带。我们研究太阳系天体原始演化动力学模型对地球水起源的影响，并根据化学约束对其进行检查。我们发现，从太阳星云仍然存在的早期阶段到散落星子的无气体清除的后期阶段，地球在其形成过程中似乎一直在吸积水。当地球质量还不到目前质量的一半时，来自木星-土星区域的小行星和彗星是第一批水输送者。目前地球上的大部分水是由一些行星胚胎携带的，这些行星胚胎最初形成于外小行星带，并在地球形成的最后阶段由地球吸积。最后，由于来自天王星-海王星区域和柯伊伯带的彗星，出现了最多占现有水量 10% 的晚饰层。这几个水库吸积的最终结果是，地球上的水基本上具有小行星带外层凝结水的典型 D/H 比。这与海洋中的 D/H 比非常接近碳质球粒陨石中水包裹体的 D/H 比平均值的观察结果一致。
In the primordial solar system, the most plausible sources of the water accreted by the Earth were in the outer asteroid belt, in the giant planet regions, and in the Kuiper Belt. We investigate the implications on the origin of Earth's water of dynamical models of primordial evolution of solar system bodies and check them with respect to chemical constraints. We find that it is plausible that the Earth accreted water all along its formation, from the early phases when the solar nebula was still present to the late stages of gas-free sweepup of scattered planetesimals. Asteroids and the comets from the Jupiter-Saturn region were the first water deliverers, when the Earth was less than half its present mass. The bulk of the water presently on Earth was carried by a few planetary embryos, originally formed in the outer asteroid belt and accreted by the Earth at the final stage of its formation. Finally, a late veneer, accounting for at most 10% of the present water mass, occurred due to comets from the Uranus-Neptune region and from the Kuiper Belt. The net result of accretion from these several reservoirs is that the water on Earth had essentially the D/H ratio typical of the water condensed in the outer asteroid belt. This is in agreement with the observation that the D/H ratio in the oceans is very close to the mean value of the D/H ratio of the water inclusions in carbonaceous chondrites.