Earliest Evolved Rocks: A Solar System Perspective

Granitic rocks dominate Earth’s continental crust, yet the Hadean record is severely limited. Extraterrestrial evolved lithologies, crystallized under predominantly anhydrous, plate tectonics-free conditions analogous to those of early Earth, provide valuable analogues. This review synthesizes lunar, asteroidal, Martian, and candidate Venus/Mercury data, revealing that partial melting of mafic protoliths, not fractional crystallization or silicate liquid immiscibility, represents the dominant formation mechanism. Granitic magmatism persisted episodically from merely 1.11 Myr after Solar System formation through at least 3.87 Ga, with estimated abundances of 0.2%–2% representing a conservative lower limit. These findings imply that Hadean Earth possessed the thermal and compositional prerequisites for analogous magmatism, suggesting that substantial felsic material may have been present, though quantitative estimates remain unwarranted given current data limitations. By establishing a comparative planetary framework, this study illuminates pathways for reconstructing Hadean crustal differential processes, highlighting priorities for future exploration missions targeting cryptic silicic reservoirs, particularly deep-crustal exposures in large lunar impact basins and in situ characterization of Venusian highland terrains.