Scientists at The University of Texas at Austin have issued a significant revision to the geological timeline of a meteor impact structure located beneath Ames, Oklahoma. The crater, which extends for miles underground and serves as a major oil and gas producer, has been the subject of ongoing research into Earth’s impact history.
For decades, the Ames impact structure was believed to be part of a cluster of meteor strikes across North America that occurred roughly 467.5 million years ago during the Ordovician Meteor Event. The clustering of impacts during this timeframe led some researchers to theorize that Earth may have once been encircled by a ring of asteroid debris similar to Saturn’s rings during the Middle Ordovician period.
UT researchers, led by associate professor Elizabeth Catlos, employed a different dating method involving zircon crystals extracted from granite altered by the impact. Through this analysis, the team determined the meteorite struck approximately 370 million years ago during the Late Devonian period, making the crater nearly 100 million years younger than previously calculated. Previous dating had relied on biological evidence, specifically fossils of conodonts, an ancient eel-like organism, found in the rock layers. However, Catlos noted these fossils were likely millions of years old when the impact occurred, having been churned up and mixed into the rocks during the collision.
The new timeline places the Ames impact closer to the Frasnian-Famennian mass extinction event, which occurred approximately 372 million years ago and resulted in the loss of a significant portion of marine life. Researchers used specialized imaging techniques in collaboration with NASA to confirm the zircon crystals had been affected by the meteor strike, as impact events create distinctive recrystallization patterns detectable through cathodoluminescence and electron backscatter diffraction. The findings were published in July in Meteoritics & Planetary Science and suggest implications for understanding whether mass extinctions were primarily triggered by extraterrestrial events or geological processes within Earth itself.
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