¹Richard J. Anslow,²Maylis Landeau,¹Amy Bonsor,^1,3Jonathan Itcovitz,^1,4Oliver Shorttle
Journal of Geophysical Research: Planets (in Press) Open Access Link to Article [https://doi.org/10.1029/2025JE009328]
¹Institute of Astronomy, University of Cambridge, Cambridge, UK
²Université de Paris, Institut de Physique du Globe deParis, CNRS, Paris, France
³Department of Civil and Environmental Engineering, Imperial College London, London, UK
⁴Department of Earth Sciences, University of Cambridge, Cambridge, UK
Published by arrangement with John Wiley & Sons

The excess abundance of highly siderophile elements (HSEs), as inferred for the terrestrial planets and the Moon, is thought to record a “late veneer” of impacts after the giant impact phase of planet formation. Estimates for total mass accretion during this period typically assume all HSEs delivered remain entrained in the mantle. Here, we present an analytical discussion of the fate of liquid metal diapirs in both a magma pond and a solid mantle, and show that metals from impactors larger than approximately 1 km will sink to Earth’s core, leaving no HSE signature in the mantle. However, by considering a collisional size distribution, we show that to deliver sufficient mass in small impactors to account for Earth’s HSEs, there will be an implausibly large mass delivered by larger bodies, the metallic fraction of which lost to Earth’s core. There is therefore a contradiction between observed concentrations of HSEs, the geodynamics of metal entrainment, and estimates of total mass accretion during the late veneer. To resolve this paradox, and avoid such a mass accretion catastrophe, our results suggest that large impactors must contribute to observed HSE signatures. For these HSEs to be entrained in the mantle, either some mechanism(s) must efficiently disrupt impactor core material into
0.01 mm fragments, or alternatively Earth accreted a significant mass fraction of oxidized (carbonaceous chondrite-like) material during the late veneer. Estimates of total mass accretion accordingly remain unconstrained, given uncertainty in both the efficiency of impactor core fragmentation, and the chemical composition of the late veneer.

¹Oleg S. Vereshchagin,¹Maya O. Khmelnitskaya,¹Natalia S. Vlasenko,¹Elena N. Perova,¹Mikhail N. Murashko,²Yevgeny Vapnik,¹Elena S. Sukharzhevskaya,³Albina G. Kopylova,^1,4Sergey N. Britvin
Journal of Geophysical Research: Planets (in Press) Link to Article [https://doi.org/10.1029/2025JE009396]
¹Saint Petersburg State University, University Embankment 7/9, St. Petersburg, Russian Federation
²Department ofGeological and Environmental Sciences, Ben‐Gurion University of the Negev, Beer‐Sheva, Israel
³Diamond and PreciousMetal Geology Institute, Siberian Branch, Russian Academy of Sciences, Yakutsk, Russia
⁴Nanomaterial Research Center,Kola Science Centre, Russian Academy of Sciences, Apatity, Russia
Published by arrangement with John Wiley & Sons

Iron is one of the most common elements on Earth and is present in the modern crust mainly in the form of (hydro)oxides and silicates, whereas terrestrial (telluric) native Fe is extremely rare. It is generally assumed that telluric Fe differs greatly in its chemical composition and mineralogy from the metal of iron meteorites, indicating different modes of formation. We uncover haxonite (NiFe22C6) and uakitite (VN) within telluric iron assemblages in terrestrial crustal rocks (volcanic rocks of the Norilsk ore region, Russia and metamorphic rocks of the Hatrurim Basin, Israel, respectively). Both minerals were previously discovered in iron meteorites and were thought to be absent in Earth’s crustal rocks. Consequently, we analyzed available data on terrestrial rocks containing native iron and iron meteorites and compared their oxygen-free mineral assemblages. The resemblance in mineralogy suggests that at least some metal-rich asteroids may have formed in a manner similar to telluric iron. We suggest that heating at low pressures (T ≈ 1000°C, P < 10 MPa) of the primary Fe-bearing silicates in the presence of organic matter led to the formation of an iron melt at low oxygen fugacity (up to 5 units below Fe-FeO buffer). Significant differences in the geochemistry of terrestrial and extraterrestrial iron are associated with different degrees of evolution of the primary minerals involved in their formation.