Asteroid impact sulfur release less lethal in dinosaur extinction

Asteroid impact sulfur release less lethal in dinosaur extinction
by Erica Marchand
Paris, France (SPX) Jan 17, 2025

Approximately 66 million years ago, a massive asteroid known as the Chicxulub impactor struck the Yucatan Peninsula in present-day Mexico. Measuring an estimated 10 to 15 kilometers in diameter, the asteroid left a colossal 200-kilometer-wide crater. This event triggered rapid climate changes that ultimately caused the extinction of non-avian dinosaurs and about 75% of Earth's species. A significant factor in this mass extinction was an "impact winter" caused by the release of vast amounts of dust, soot, and sulfur into the atmosphere. These materials blocked sunlight, plunged the planet into extreme cold, and disrupted global photosynthesis for years or even decades.

Previous studies have highlighted sulfur as the critical element driving global cooling and extinction following the impact. However, estimates of the sulfur released into the atmosphere have varied significantly due to uncertainties in factors such as the composition of the rocks at the impact site, the asteroid's speed and angle of impact, and the shock pressures involved.

A recent study led by Katarina Rodiouchkina and her team has provided a more precise estimate of the sulfur released during the Chicxulub impact. By analyzing sulfur concentrations and isotopic compositions from newly drilled cores of impact rocks, as well as sedimentary profiles around the K-Pg boundary from sites worldwide, researchers determined the total sulfur emission from the event.

"Instead of focusing on the impact event itself, we focused on the aftermath of the impact," explained chemist Katarina Rodiouchkina. "We first analyzed the sulfur fingerprint of the rocks within the crater region that were the source of sulfate aerosols released into the atmosphere. These sulfate aerosols were distributed globally and eventually deposited back onto the Earth's surface in the months to years after impact. The sulfur was deposited around the K-Pg boundary layer in sedimentary profiles all over the world. We used the corresponding change in the isotopic composition of sulfur to distinguish impact-related sulfur from natural sources and the total amount of sulfur released was calculated through mass balance."

The study found that approximately 67 +/- 39 billion tons of sulfur were released into the atmosphere - a figure about five times lower than prior estimates derived from numerical models. This suggests that the resulting "impact winter" was less severe than previously thought. The less drastic temperature decline and faster climate recovery may have contributed to the survival of 25% of species following the event. Although sulfur remains a significant driver of global cooling, recent research from the Royal Observatory of Belgium and Vrije Universiteit Brussel indicates that a massive plume of fine, micrometer-sized dust particles likely played a key role in blocking sunlight and extending the period of darkness, further exacerbating the environmental crisis.

This research involved collaborations among institutions such as Lulea University of Technology, Ghent University, Vrije Universiteit Brussel, Royal Observatory of Belgium, Universite Libre de Bruxelles, Leibniz-Institute for Baltic Sea Research Warnemunde, University of Greifswald, University of Rostock, Australian Laboratory Services Scandinavia AB, Katholieke Universiteit Leuven, and the Royal Belgian Institute of Natural Sciences. Funding was provided by the Research Foundation Flanders (FWO) through the EOS-Excellence of Science program, VUB Strategic Research Program, Chicxulub BRAIN-be project, and FED-tWIN MicroPAST project, among others.

Research Report:Reduced contribution of sulfur to the mass extinction associated with the Chicxulub impact event