Late Accretion and the Late Veneer

TL;DR

This paper explores the concepts of Late Veneer and Late Accretion in Earth's formation, analyzing their definitions, processes, and relationships to better understand Earth's geochemical history.

Contribution

It clarifies the complex relationship between Late Veneer and Late Accretion within Earth's accretion history, highlighting the ambiguities and processes involved.

Findings

Late Veneer explains siderophile element abundance in Earth's mantle.

Earth's differentiation was likely intermittent, affecting the timing of accretion phases.

The relationship between Late Veneer and Late Accretion remains complex and not fully defined.

Abstract

The concept of Late Veneer has been introduced by the geochemical community to explain the abundance of highly siderophile elements in the Earth's mantle and their chondritic proportions relative to each other. However, in the complex scenario of Earth accretion, involving both planetesimal bombardment and giant impacts from chondritic and differentiated projectiles, it is not obvious what the "Late Veneer" actually corresponds to. In fact, the process of differentiation of the Earth was probably intermittent and there was presumably no well-defined transition between an earlier phase where all metal sunk into the core and a later phase in which the core was a closed entity separated from the mantle. In addition, the modellers of Earth accretion have introduced the concept of "Late Accretion", which refers to the material accreted by our planet after the Moon-forming event. Characterising Late Veneer, Late Accretion and the relationship between the two is the major goal of this chapter.