Largest impact crater near Falklands Islands?

Some 66 million years ago a comet struck the earth near Yucatan in modern day Mexico. The impact was so devastating that it heralded the end of the dinosaur. Evidence of that impact is the 200-kilometer diameter Chicxulub impact crater discovered in and near the Yucatan in the late 1970s.

But the earth has witnessed many more mass extinctions, the largest of them being the Permian–Triassic (P–Tr) extinction event, which occurred about 252 million years ago. It formed the boundary between the Permian and Triassic geologic periods, as well as the Paleozoic and Mesozoic eras. This mass extinction killed 90% to 96% of all species.

So, the question is: where is that impact crater?

A very large 250 to 300 kilometers wide circular geophysical anomaly (visible both in gravity and magnetic maps) is has been discovered on the Falkland Plateau to the northwest of West Falkland Island in the southern Atlantic Ocean[1][2].

The scientists point to specific features that indicate the basin is an impact crater. They note that it is completely buried by sediments from more recent eras, which indicates it was formed long before its surroundings, and that it has no topographic expression on the present sea floor. Key to the basin’s identification as a potential impact crater are the decrease in the strength of Earth’s gravity over the site, indicating a large basin filled with younger low-density sediments and a strong increase in the strength of Earth’s magnetism at the site. The latter is characteristic of large impact structures, such as the Chicxulub impact crater discovered in the Yucatan.

If the Falklands basin is really an impact crater, and it has some of the most telling features, then it is one of the largest known. The scientists estimate the age of the basin to be from the late Paleozoic Era–approximately 270 to 250 million years ago.

[1] Rocca, Presser: A possible new very large impact crater in Malvina Islands in Historia Natural – 2015
[2] Rocca et al: Geophysical evidence for a large impact structure on the Falkland (Malvinas) Plateau in Terra Nova - 2017