Petrogenesis of an augite-bearing melt rock in the Chicxulub structure and its relationship to K/T impact spherules in Haiti

Geophysical anomalies on the Yucatán peninsula define a buried circular structure with an approximate diameter of 180 km (refs 1-3). These anomalies, along with stratigraphic and petrological data, including evidence for shock metamorphism, have been used to interpret the structure as an impact crater This structure, known as Chicxulub, is particularly interesting because it formed at or near the end of the Cretaceous period, in the geographical region where an impact is believed to have occurred, in large part because of a thick ejecta deposit found on Haiti Glassy tektite-like relics in this depositare unusually calcic (up to 31 wt % CaO; ref. 7), providing a further circumstantial link with the Chicxulub structure, which penetrates a carbonate and evaporite sequence Here we strengthen this link by showing that a simple chemical relationship exists between the glasses and an augite-bearing melt rock found within the Chicxulub structure, and argue that the composition of this melt rock could not easily have been produced by volcanic processes.