New Data Reported From Chicxulub Crater

Seismologists say a new three-dimensional image of Mexico’s Chicxulub crater might modify the theory concerning the 65-million-year-old asteroid impact.

Research scientist Sean Gulick at the University of Texas’ Institute for Geophysics said the new images reveal the asteroid landed in deeper water than previously assumed and released about 6.5 times more water vapor into the atmosphere than has been estimated. Most scientists agree that impact caused the extinction of most life on Earth, including the dinosaurs.

The impact site also contained sulfur-rich sediments called evaporites, which would have reacted with water vapor to produce sulfate aerosols, Gulick said. An increase in the atmospheric concentration of the compounds could have altered climate — sulfate aerosols in the upper atmosphere can have a cooling effect — and also generated acid rain, he said. Earlier studies had suggested both effects might have resulted from the impact, but to a lesser degree.

Gulick said an increase in acid rain might help explain why reef and surface dwelling ocean creatures were affected, along with large vertebrates on land and in the sea.

The research results appear in the February issue of the journal Nature Geosciences.