Three-body evidence of ca. 3.7 Ga to 3.2 Ga bombardment across the inner solar system
Carolyn A. Crow, Timmons M. Erickson, Rita Economos, Katelyn Lehman-Franco, Jeremy W. Boyce, A. Marcus Richards, Connor A. Diaz, Rebecca M. Flowers, Maryjo Brounce, Blair Schoene, Jeffery A. Benowitz
Geology, May 12, 2026
“The intensity of Archean meteoroid bombardment of the inner solar system is disputed. Here, we present the first observation of cubic zirconia phase heritage in baddeleyite (monoclinic ZrO2) from a lunar meteorite, Northwest Africa (NWA) 12593. Cubic zirconia is a high-temperature mineral structure that forms in superheated impact melt at temperatures >∼2370 °C. 207Pb-206Pb geochronology of baddeleyite grains with phase heritage in NWA 12593 supports an impact age of 3486 ± 10 Ma. The presence of cubic zirconia heritage in this lunar meteorite suggests a large (>30 km) crater forming event at this time. This result aligns with ca. 3.5 Ga large crater forming impacts from two other inner solar system bodies—Earth and Vesta. This period of coeval large crater forming impact events across the inner solar system was synchronous with enigmatic events in Archean Earth history, including the earliest evidence of the evolution of cellular life on Earth. Placed in a comprehensive record of ca. 3.8−3.0 Ga inner solar system impact events, high-intensity meteorite bombardment continued well beyond the ca. 3.9 Ga cataclysmic period.”
