Scientists have new insight into the damage caused by a Rhode Island–size asteroid impact more than 3 billion years ago, making the rock that wiped out the dinosaurs look like a lightweight.
The massive asteroid impact wiping out the dinosaurs 65 million years ago is a big chapter in Earth’s history, but scientists have also studied hints of bigger events that could have changed Earth’s geologic evolution before dinosaur extinction. Now, in a new study from Stanford University scientists, researchers have taken a closer look at the effects of such an impact event some 3.26 billion years ago.
In dimensions alone, this older asteroid makes the Chicxulub impactor look wimpy — it measured in at between 37 km to 58 km (23 miles to 36 miles) wide, a good three to five times larger. That’s close to the size of Rhode Island. The impact from such a rock would have created a jolt greater than a magnitude-10.8 earthquake, and the seismic-like waves would have lasted for roughly 15 minutes. Its affects would have been cataclysmic and devastating to the environment worldwide — imagine the classic end-of-the-world scenario. The crater itself would have been just under 500 km (300 miles) wide, about four times the size of the Big Island of Hawaii.
Evidence for this Earth-changing event remains preserved in the rocks of the Barberton greenstone belt in South Africa (located east of Johannesburg, near the border with Swaziland). The geologic structure of the Barberton region implies that the region was underwater when the impactor struck. The cosmic punch fractured the rock, and liquefied sediment filled these cracks, later solidifying and forming sheets of rock called chert dikes that are present today.
The study, coauthored by Stanford scientists Norman Sleep and Donald Lowe, is one of the first to model an impact occurring during this period of Earth’s evolution. Furthermore, scientists think that the asteroid could have been one of some final punches to hit Earth at the very tail end of the aptly-named Late Heavy Bombardment period (3 to 4 billion years ago).
You can read more about the study in the American Geophysical Union’s press release (first paragraph below). The paper will appear in an upcoming Geochemistry, Geophysics, Geosystems.
AMERICAN GEOPHYSICAL UNION RELEASE:
Scientists Reconstruct Ancient Impact That Dwarfs Dinosaur-extinction Blast
Picture this: A massive asteroid almost as wide as Rhode Island and about three to five times larger than the rock thought to have wiped out the dinosaurs slams into Earth. The collision punches a crater into the planet’s crust that’s nearly 500 kilometers (about 300 miles) across . . .
Read the full press release.