Introduction

The intriguing composition of our planet, as revealed by the isotopic signatures of meteorites and the bulk silicate Earth (BSE), showcases a crucial blend of “carbonaceous” (CC) and “non-carbonaceous” (NC) materials.

Proportions of Materials

Recent studies reveal that the proportion of carbonaceous materials contributing to Earth's makeup varies among elements, primarily governed by their volatility and their tendency to partition into metallic states.

Significant Delivery of CC Materials

Notably, the evidence suggests that while the bulk of materials accumulated on Earth were NC-dominant, there was a significant delivery of CC-dominant material—enriched in moderately volatile elements—during the closing stages of Earth’s formation, around 2-10% of its total accretion time.

Contrasts with Dynamic Models

This late influx of CC materials stands in stark contrast to dynamic models indicating that CC objects were integrated into the inner solar system much earlier, coinciding with the growth and migration phases of the giant planets.

Larger CC Embryos

Furthermore, this phenomenon posits that the materials that dispersed towards Earth primarily comprised larger CC embryos rather than numerous smaller planetesimals.

Impact on Planetary Formation

This raises an exciting prospect: Earth may have assimilated a few of these massive carbonaceous bodies while Mars missed out, leading to the possibility that at least one of these CC embryos collided with Earth later in its formation process—when approximately 90% of its accretion was complete.

Late Impact and Moon Formation

Such a late impact not only aligns with the scenarios surrounding the formation of the Moon, resulting from a collision with a significant NC body, but also suggests the substantial differentiation within Earth's mantle was largely preserved despite this cataclysm.

Implications for Planetary Studies

The implications of these findings go beyond our planet alone, as they challenge existing theories about planetary formation and the distribution of materials in our solar system.

Conclusion and Future Research