The effect of an asteroid or comet is acknowledged because of the principal reason for the mass extinction that killed most of the dinosaurs and about three-quarters of the planet’s plant and animal species 66 million years ago.
However, massive volcanic eruptions in India might also have contributed to the extinction. Scientists have long debated the importance of the Deccan Traps eruptions, which started earlier than the influence and lasted, on and off, for nearly one million years, punctuated by the impact event.
Now, a University of Michigan-led geochemical evaluation of fossil marine mollusk shells from across the globe is providing new insights into each of the climate response and environmental mercury contamination at the time of the Deccan Traps volcanism.
From the same shell specimens, the researchers discovered what seems to be a global sign of each abrupt ocean warming and distinctly elevated mercury concentrations. Volcanoes are the biggest natural supply of mercury coming into the atmosphere.
The dual chemical fingerprints start earlier than the impact event, and line in with the onset of the Deccan Traps eruptions.
When the group of researchers compared the mercury levels from the ancient shells to concentrations in freshwater clam shells collected at a present-day site of industrial mercury pollution in Virginia’s Shenandoah Valley, the levels have been roughly equal.
Within the new study, each signal is present in the same specimens—an essential first, in accordance with the authors. The new method is expected to have broad functions for the research of mass extinctions and climate perturbations within the geological record, in accordance with the researchers.