^1,2Jinting Kang, ¹Zhengyu Hou, ¹Haochen Yang, ¹Xue Tang, ^2,3Weibiao Hsu, ^1,2Fang Huang
Journal of Geophysical Research: Planets, 131, e2026JE009894
Link to Article [DOI: 10.1029/2026JE009894]
¹State Key Laboratory of Lithospheric and Environmental Coevolution, School of Earth and Space Sciences, University of Science and Technology of China, Hefei, China
²Deep Space Exploration Laboratory, Hefei, China
³Purple Mountain Observatory, Chinese Academy of Sciences, Nanjing, China

Published by arrangement with John Wiley & Sons

Magma oceans represent a pivotal stage in the early evolution of terrestrial planets. Early-formed asteroids, driven by the decay of ²⁶Al, may have also experienced such magma ocean processes. To investigate potential magma ocean differentiation on asteroid 4 asteroids, we reported high-precision iron isotope data for 25 eucrites and 13 diogenites. Eucrites exhibit a δ⁵⁶Fe range of approximately 0.1‰, varying from −0.044 to 0.073‰, with a mean value of 0.020 ± 0.013‰ (2SE, N = 25). Diogenites display δ⁵⁶Fe ranging from −0.051 to 0.018‰, yielding an average of −0.004 ± 0.011‰ (2SE, N = 13). The observed Fe isotope variation and offset between eucrites and diogenites cannot be produced by terrestrial weathering, impacts, and core formation. Combined with MELTS modeling using two different initial compositions for Vesta, the isotope variation can be explained by magma ocean differentiation. A cross-planetary comparison is made with the Moon, where magma ocean differentiation and associated Fe isotope variations have been extensively studied. Vestan samples exhibit remarkably limited δ⁵⁶Fe variation (∼0.1‰) compared to lunar basalts (∼0.3‰). This dichotomy may reflect distinct magma ocean evolution pathways across planetary bodies: later pyroxene crystallization, the absence of ilmenite-driven mantle overturn, and rapid cooling in the case of Vesta. Thus, planetary geochemical diversity is fundamentally shaped by magma ocean dynamics modulated by body size, composition, and thermal history.