Discovery of mafic impact melt in the center of the Vredefort dome: Archetype for continental residua of early Earth cratering?

Researchers have uncovered mafic impact melt within the central uplift of the 2.02 billion-year-old Vredefort Dome, challenging long-held assumptions about the preservation of such materials on Earth's ancient crust. The discovery, identified as decimeter-scale dikes and lenses of variably foliated gabbronorite amid Archean gneiss, provides critical evidence for significant impact-induced melting in early planetary crust modification. Zircon analyses revealed a dominant population of 2.02 Ga unshocked igneous zircon with temperatures ranging from 800-900 °C, mirroring those found in the Sudbury impact melt sheet. The study suggests that these melts originated from the once superjacent Witwatersrand basin lithologies and offers new benchmarks for identifying remnants of large cratering events on Earth's cratons.

Cupelli, C. L., Moser, D. E., Barker, I. R., Darling, J. R., Bowman, J. R., & Dhuime, B. (2014). Discovery of mafic impact melt in the center of the Vredefort dome: Archetype for continental residua of early Earth cratering? Geology, 42(5), 403–406. https://doi.org/10.1130/g35297.1