Stable Isotope Evidence for Impact-Related Pseudotachylite Formation at Vredefort by Local Melting of Dry Rocks

A groundbreaking study at the Vredefort Dome reveals that pseudotachylite, a rock formed during impact events, was likely created through local melting of dry rocks. Stable isotope analysis shows that both granophyre (impact melt) and pseudotachylite share nearly identical oxygen and hydrogen isotopic compositions, indicating they originated from the same source without significant interaction with water. The study also found a bimodal distribution in water content within pseudotachylites, suggesting two distinct formation processes or sources. These findings challenge previous assumptions about the relationship between pseudotachylite and granophyre, providing new insights into the mechanisms of impact-related melt formation.

HARRIS, C., FOURIE, D. S., & FAGERENG, A. (2013). STABLE ISOTOPE EVIDENCE FOR IMPACT-RELATED PSEUDOTACHYLITE FORMATION AT VREDEFORT BY LOCAL MELTING OF DRY ROCKS. South African Journal of Geology, 116(1), 101–118. https://doi.org/10.2113/gssajg.116.1.101