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Scientists from the University of Arizona, led by David Kring, say that wildfires ignited by debris ejected from the Chicxulub crater 65 million years ago spread over most of the equatorial regions of the world. The research, published in the Journal of Geophysical Research, involved calculating the amount of heat generated on the ground by the plume of hot debris thrown out of the 170 km diameter crater. The models suggest that the debris rained back down on the Earth for about four days and burnt up like meteors as it re-entered the atmosphere leading to intense heating.
Kring and colleages model's predict that pulses of fires where generated as the debris fell back to Earth. Twenty five percent of the debris fell within two hours of the impact, says Kring, and 85 percent within 72 hours. The highest energy debris, that led to the most intense heating, fell back on the crater itself and on the antipode, the point on the opposite side of the Earth corresponding to India. However, because the Earth rotates it turned below the falling plume of debris and the fires, therefore, migrated to the west producing a trail of devastation across the equatorial regions of the Earth. The calculations also suggest that northern Asia, Europe and Antarctica may have escaped wildfires.
The impact 65 million years ago is thought by most scientists to have been responsible for the extinction of around 75 percent of land species including the Dinosaurs. Immediate effects of the impact such as the global wildfires would have devastated large areas of vegetation and probably have killed many animals. It is thought, however, to have been the change in global climate produced by the large amounts of carbon dioxide gas released by the vaporisation of limestone rocks at Chicxulub that was largely to blame for the extinction. Kring and colleages have previously suggested that the amount of carbon dioxide produced by the wildfires may have exceeded that generated for the limestones and would have significantly contributed to the change in global climate.
More info: Impact-generated Wildfires
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