Chicxulub asteroid identified as rare CO carbonaceous chondrite

A new study published in *Science Advances* analyzed nickel isotopes from clay layers worldwide and determined that the Chicxulub impactor belonged to the rare CO carbonaceous chondrite class, which makes up only about 5 % of recovered meteorites. The low sulfur, carbon and water content of CO chondrites suggests that the massive dust cloud ejected by the impact, rather than sulfur‑driven cooling, was the primary driver of the post‑impact “impact winter” that blocked sunlight for months.

Separate research from Purdue University, appearing in the *Journal of Geophysical Research: Biogeosciences*, proposes that the same fine‑grained dust acted as a thermal blanket, trapping heat near the surface and raising temperatures to lethal levels within one to two hours. This rapid heating could have ignited widespread wildfires and caused the near‑instantaneous loss of much of the terrestrial fauna, revising earlier models that emphasized a prolonged global cooling phase.