Was this the trigger of the “Great Dying” mass-extinction event (and a host of wild conspiracy theories)?
A NASA satellite detected a 300-mile-wide “gravity anomaly” below the ice of Antarctica consistent with a giant asteroid impact and the volcanic flows of Siberian Traps that continued for roughly two million years and spanned the Permian–Triassic mass extinction, which occurred between 251 to 250 million years ago. The impact crater is estimated an nearly three times the size of the Chicxulub crater that ended the dinosaur epoch (image above), and presumably formed before the Cretaceous formation of the east Antarctic coast.
The Gravity Recovery and Climate Experiment (GRACE) was a joint mission of NASA and the German Aerospace Centre that ran from March 2002 to October 2017. By measuring gravity anomalies, GRACE showed how mass is distributed around the planet and how it varies over time.
However, one discovery in Antarctica has received far more attention than the rest of the mission. In 2006, a team of researchers led by Ralph von Frese and Laramie Potts used GRACE data to discover the anomaly below the ice. The team determined this to be a massive impact crater buried below the ice for millions of years, likely caused by an asteroid.
New 2018 details on the east Antarctic gravity field from the Gravity Recovery and Climate Experiment (GRACE) mission revealed a prominent positive free-air gravity anomaly over a roughly 500-kilometer diameter buried basin centered on Antarctica’s in north-central Wilkes Land.
It extensively thinned and disrupted the Wilkes Land crust where the Kerguelen hot spot and ancient Gondwana rifting developed but left the adjacent Australian block relatively undisturbed. The micrometeorite and fossil evidence suggests that the impact may have occurred at the beginning of the greatest extinction of life on Earth at ~260 Ma ( Ma, “mega-annum”, is a million years) when the Siberian Traps were on the opposite side of the planet.
Antipodal volcanism is common to large impact craters of the Moon and Mars and may also account for half of the Earth’s large igneous provinces and hot spots. The GRACE data suggest that the impact may have triggered the ‘‘Great Dying’’ at the end of the Permian and contributed to the development of the hot spot that produced the Siberian Traps and now may underlie Iceland.
The glacial ice up to a few kilometers thick that has covered the crater for the past 30–40 million years poses formidable difficulties to sampling the subglacial geology. Thus, the most expedient and viable test of the prospective crater is to survey it for relevant airborne gravity and magnetic anomalies.
The anomaly of course has triggered a host of conspiracy theories that secret Nazi bases were allegedly built there during World War Two, with some evidence showing entrances around the continent and that in 1991 the KGB released previously classified documents that shed light on the infamous Operation Highjump that showed the US Navy went on countless secret missions to Antarctica.
Another popular claim is that Admiral Richard E. Byrd ran a secret project with the US Navy in the 1940s that used more than 4,000 men, 13 ships and 33 aircrafts and the public reason was to research Antarctica. “But the true purpose was to investigate an entrance found in the center of the ice leading to an ‘inner Earth’.”
The Daily Galaxy via ResearchGate.com
Image credit: With thanks to Barcroft Productions/BBC