UF researcher looks at ancient temperatures to resolve a scientific debate.
University of Florida geochemist Andrea Dutton and colleagues at the University of Michigan have utilized a new technique of analysis to reconstruct Antarctic ocean temperatures that supports the idea that the combined impacts of volcanic eruptions and an asteroid impact brought about one of Earth’s biggest mass extinctions 66 million years ago.
April 21, 1990 eruption cloud from Mt. Redoubt Volcano as viewed to the west from the Kenai Peninsula in Alaska. A volcanic eruption produces lava, ash clouds, and landslides that devastate surrounding flora and fauna. The environmental effects of a large eruption in India may have exacerbated the damage caused by the asteroid that struck the Yucatan peninsula.
Their research published in the journal Nature Communications used a recently developed technique called the carbonate clumped isotope paleothermometer to analyze the chemical composition of fossil shells from the Antarctic ocean. This analysis shows that ocean temperatures rose approximately 14 degrees Fahrenheit, and links these findings to two previously documented warming events that occurred near the end of the Cretaceous Period: one related to volcanic eruptions in India, and the other, tied to the impact of an asteroid or comet on the Yucatan Peninsula in Mexico.
The Chicxulub asteroid, estimated to be 10 km (6.2 mi) or larger, struck the Yucatán peninsula 66 million years ago, causing massive land distortion, tsunamis, and ash clouds.
To create their new temperature record, which spans 3.5 million years at the end of the Cretaceous and the start of the Paleogene Period, the researchers analyzed the isotopic composition of 29 remarkably well-preserved shells of clam-like bivalves collected on Antarctica’s Seymour Island.
The data show two significant temperature spikes. The first corresponds to the eruption of the Deccan Traps flood basalts in India. The other lines up exactly with the asteroid impact, which, in turn, may have sparked a renewed phase of volcanism in India. Intriguingly, both events are associated with extinction events of nearly equal magnitude on Seymour Island, Antarctica.
“The Deccan Traps weakened the ecosystems before the asteroid slammed into the Earth — it’s consistent with an idea called the press-pulse hypothesis: a ‘one-two punch’ that proved devastating for life on Earth.”
“We have evidence on this site on Seymour Island in Antarctica that climate change is linked to both of these extinction events,” says Dutton. “If you look at what types of species that went extinct during the first extinction pulse, they’re different than the types that went extinct during the second pulse. That indicates that it may have been a different kill mechanism for those two different extinction pulses. The Deccan Traps weakened the ecosystems before the asteroid slammed into the Earth — it’s consistent with an idea called the press-pulse hypothesis: a ‘one-two punch’ that proved devastating for life on Earth.”