In a new paper, researchers address the "uncomfortably close" occurrence of the Chicxulub impact in the Yucatán and the most voluminous phase of the Deccan Traps flood basalt eruptions in India. Specifically, the researchers argue that the impact likely triggered most of the immense eruptions of lava in India -- that it was not a coincidence but was a cause-and-effect relationship.
Knowledge and study of the Deccan Traps eruptions have consistently cast a shadow of doubt on the theory that the Chicxulub impact was the sole cause of the end-Cretaceous mass extinction, most infamous for killing off Earth's dinosaurs. But Richards and colleagues write that historical evidence for the triggering of volcanoes by large earthquakes, coupled with a wide range of data, show that the massive outpouring of Deccan lavas are likely to have been triggered by the Chicxulub impact -- and thus following on as a secondary disaster.
"The chances of that occurring at random are minuscule," says Dr. Mark Richards. "It's not a very credible coincidence."
Several of the authors visited India in April 2014 to obtain lava samples for dating, and noticed that there are pronounced weathering surfaces, or terraces, marking the onset of the huge Wai subgroup flows.
This geological evidence likely indicates a period of quiescence in Deccan volcanism prior to the Chicxulub impact, which, says Richards, "gave this thing a shake," thus mobilizing a huge amount of magma over a short period of time.
Richards and colleagues write that while the Deccan eruptions probably spewed massive amounts of carbon dioxide and other noxious, climate-modifying gases into the atmosphere, "It's still unclear if this contributed to the demise of most of life on Earth at the end of the Age of Dinosaurs."
Mark A. Richards et al., Triggering of the largest Deccan eruptions by the Chicxulub impact, GSA Bulletin, http://dx.doi.org/10.1130/B31167.1.