2025/10/29 by Matthew S. Huber, Elizaveta Kovaleva, Jonathan Hainsworth +5
Earth and Planetary Sciences · Physics and Astronomy · #Astro and Planetary Science #Paleontology and Stratigraphy of Fossils #Planetary Science and Exploration
paper · doi:10.1016/j.precamres.2025.107954
openalex created_date 2025/10/29 · openalex publication_date 2025/10/29 · openalex updated_date 2026/07/28
• Previously unrecognized ejecta from world’s largest impact crater discovered. • Discovery of shocked minerals in iron mining district. • World’s largest impact crater was probably on land, not sea. • South African iron mines are partially excavating impact ejecta. The Vredefort impact structure in South Africa is among the largest and oldest impact structures currently known on Earth. Due to extensive erosion, the proximal ejecta has been thought to have been removed completely. However, we find that sediments of the Doornfontein Member of the Gamagara Formation in the Griqualand West Basin resemble impact ejecta. They are located ca. 500 km west of the center of the Vredefort structure, which is within the modelled distance for the proximal ejecta, and are chronostratigraphically constrained to be between 1928 ± 4 Ma and 2222 ± 13 Ma, overlapping with the Vredefort event age (2019 ± 2 Ma). The stratigraphy of the Doornfontein Member includes an up to 100 m thick polymict breccia sequence that includes fragments of banded iron formation, chert, and carbonates, capped by accretionary lapilli. Shock metamorphic evidence in the form of quartz grains with planar deformation features and planar fractures, as well as granular zircons, are entrained within the breccia, confirming an impact origin. Primary compositions are obscured due to hematite alteration. We suggest that the economically significant Doornfontein Member represent proximal ejecta generated by the Vredefort event. Our discovery could represent the oldest described crater-ejecta pair and shows the potential for the preservation of massive Paleoproterozoic ejecta layers.