I. Chondritic Ingassing:
1. Impact Delivery: During the early stages of planetary formation in the solar system, frequent cometary and asteroidal impacts played a vital role in delivering carbon and volatile-rich material from beyond the snowline (present-day main asteroid belt) into the interiors of rocky planets like Earth and the Moon. These impacts bombarded both planets with carbonaceous and volatile-laden chondrites, leading to the implantation of carbon into their interior reservoirs.
II. Indigenous Sources:
1. Core Formation Processes: Early differentiation and core formation contribute to carbon delivery in the mantles. During metal-silicate segregation, elements and compounds that do not efficiently partition into metallic cores might remain within the rocky silicate portion and concentrate in the mantle and crust. As carbon tends to dissolve in metallic melts to a limited extent, this process likely resulted in the partitioning of some carbon into terrestrial and lunar mantles.
These processes, often termed primordial or early carbon input, facilitated the initial establishment of carbon levels in both terrestrial and lunar mantles. Over time, additional sources or sinks might have further influenced the carbon budget of these reservoirs.
