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An international team of researchers, including geologists from the Vrije Universiteit Brussel (VUB), has found additional evidence for the theory that a meteorite impact led to the extinction of the dinosaurs 66 million years ago.
Scientists have long believed that the impact of a 12km meteorite, estimated to have had the power of 10 billion World War II atomic bombs, had catastrophic consequences for life on earth. Analysis of rocks from the 200km-wide Chicxulub meteorite crater on the Yucatán Peninsula in Mexico now shows that this hypothesis is correct.
The researchers found no traces of sulphur in an 800m long drill core from the central part of the crater. The rocks in the subsurface surrounding the crater, on the other hand, do contain large quantities of sulphur. This confirms the theory that the meteorite caused the complete evaporation of sulphur-bearing minerals releasing an estimated 325 billion tonnes of sulphur into the atmosphere. “This enormous amount of sulphur gas formed bonds with hydrogen, creating a blanket of dust particles in the higher atmosphere that spread all over the world. As a result, there was no more sunlight on earth, and the continuing darkness ultimately resulted in the extinction of three-quarters of life on our planet, including the dinosaurs,” says VUB PhD student Pim Kaskes, who worked with colleague Sietze J. de Graaff and professors Steven Goderis and Philippe Claeys on the research.
Unique research material
The drill core, which was extracted off the coast of Mexico in 2016, has produced unique research material. “This offers a completely new perspective on the processes responsible for the creation and infill of the Chicxulub crater. With this material we can now unravel the events at ground-zero in the first minutes to days after the impact,” says Goderis. The researchers from VUB’s Analytical, Environmental and Geo-Chemistry unit used techniques such as micro-XRF – an instrument that measures the chemical composition of rocks on a scale 100 times smaller than a millimetre. “By comparing these results with descriptions of samples under the microscope, we were certain that no more sulphur-bearing minerals were present in the drill core. We could now reconstruct in detail the first days after the impact. It felt like we had been there ourselves,” says de Graaff.
This research was conducted by more than 20 scientists from all over the world, under the direction of the University of Texas in Austin. The results were published today in the prestigious scientific journal Proceedings of the National Academy of Sciences.