Earth during accretion

Fig. 2 All terrestrial carbon was initially delivered to the primitive Earth during accretion. Much of the carbon was degraded to simple carbon compounds that could then undergo synthetic geochemical reactions to produce more-complex species. However, a fraction of the delivered organic carbon was likely to survive intact, especially during late accretion. This fraction had the potential to be incorporated into the molecular systems that gave rise to the origin of life...

Tingle (1998) estimated that the mass of carbon acquired by the Earth during accretion was between 1024 and 1025 g (109—1010 Gt), 0.02-0.2 wt% C. This is two to three orders of... 

New computer simulations of the accretion process of the protoearth indicate that only a few large bodies with a high water concentration collided with the Earth during the later bombardment. They apparently came from the same region of the asteroid belt as the carbonaceous chondrites. 

Mars is more volatile-rich than Earth, reflecting a higher proportion of accreted volatilebearing planetesimals. It is also more highly oxidized than Earth, so that twice as much of its iron has remained as Fe2+ in the mantle rather than in the metallic core. Wanke and Dreibus (1988) suggested that oxidation occurred during accretion, as water in accreted planetesimals reacted with iron metal. 

Zahnle, K., Kasting, J. F., Pollack, J. B. (1988) Evolution of a steam atmosphere during Earth s accretion. Icarus, 74, 62-97. 

The low Fe abundance in the lunar mantle suggests the Moon-forming impact happened late in Earth s accretion (Canup Asphaug 2001). It may have been the last collision with another embryo. Simulations of terrestrial-planet formation find that low-velocity, oblique impacts are common (Agnor et al. 1999), so that planets like Earth and Venus are likely to experience at least one such impact during their formation. This suggests large satellites may be a common outcome of terrestrial-planet formation. 

Ballhaus C. and Ellis D. J. (1996) Mobility of core melts during Earth s accretion. Earth Planet. Sci. Lett. 143, 137-145. Bell J. F., Davis D. R., Hartmann W. K., and Gaffey M. J. 

The Lu- Hf isotopic system (half-life —37 Gyr) is, in many ways, chemically similar to Sm- Nd. In both isotopic schemes the parent and daughter elements are refractory lithophile elements, such that their relative abundances in the Earth were probably not modified during accretion, nor did they participate in core formation. Thus, as for the Sm-Nd system, the compositions of chondritic meteorites can, in principle, be used to establish bulk silicate Earth isotopic compositions and Lu/Hf ratios directly. The potential, therefore, exists for establishing a precise isotopic baseline to use for recognizing fine-scale deviations in isotopic compositions, which can then be used to reveal... 

Although the basic chemical and material building blocks for the planets and their satellites were fairly uniform during the initial formation of the solar nebula from inter-stellar cloud materials, chemical differentiation, and segregation occurred over time during accretion of the planets, and their moons such that the volatile chemical components of the solar nebula ended up as present day near-surface ice on Earth, and ice plus solid CO2 on Mars, and as ice and other molecular solids and fluids (such as hydrocarbons and ammonia) on most of the moons of Jupiter and Saturn, and as water ices and increasingly volatile species such as nitrogen in the outermost solar system. 

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