Title: The terrestrial late veneer from core disruption of a lunar-sized impactor,
Abstract: Overabundances in highly siderophile elements (HSEs) of Earth's mantle can be
explained by conveyance from a singular, immense (3000 km in a diameter) "Late
Veneer" impactor of chondritic composition, subsequent to lunar formation and
terrestrial core-closure. Such rocky objects of approximately lunar mass (about
0.01 M_E) ought to be differentiated, such that nearly all of their HSE payload
is sequestered into iron cores. Here, we analyze the mechanical and chemical
fate of the core of such a Late Veneer impactor, and trace how its HSEs are
suspended - and thus pollute - the mantle. For the statistically most-likely
oblique collision (about 45degree), the impactor's core elongates and
thereafter disintegrates into a metallic hail of small particles (about 10 m).
Some strike the orbiting Moon as sesquinary impactors, but most re-accrete to
Earth as secondaries with further fragmentation. We show that a single oblique
impactor provides an adequate amount of HSEs to the primordial terrestrial
silicate reservoirs via oxidation of (<m-sized) metal particles with a hydrous,
pre-impact, early Hadean Earth.