It is possible that one of the largest asteroid impacts in the history of the Earth has been located in Antarctica. A land mass concentration detected by satellite mapping of the gravitational field suggests a crater that is around 500 km in diameter (300 miles) and was probably created about 250 million years ago. It has been further suggested that this large impact event may have contributed to the greatest known mass extinction, called the Permian-Triassic extinction, which occurred in the same time frame. This extinction has been previously attributed to volcanic activity in an area known as the Siberian Traps. It has been noted that asteroid strikes may contribute to volcanic activity by sending a shock wave through the planet to the antipodal (opposite) area where it disrupts the surface allowing volcanic venting. The theory of this article has not yet been confirmed. Several kilometers of ice on top of the land mass complicate the process of gathering evidence and make drilling problematic.
Big Bang in Antarctica: Killer Crater Found Under Ice – [researchnews.osu.edu]
Ancient mega-catastrophe paved way for the dinosaurs, spawned Australian continent
COLUMBUS, Ohio — Planetary scientists have found evidence of a meteor impact much larger and earlier than the one that killed the dinosaurs — an impact that they believe caused the biggest mass extinction in Earth’s history.
The 300-mile-wide crater lies hidden more than a mile beneath the East Antarctic Ice Sheet. And the gravity measurements that reveal its existence suggest that it could date back about 250 million years — the time of the Permian-Triassic extinction, when almost all animal life on Earth died out.
Its size and location — in the Wilkes Land region of East Antarctica, south of Australia — also suggest that it could have begun the breakup of the Gondwana supercontinent by creating the tectonic rift that pushed Australia northward.
Wilkes Land crater – [wikipedia.org]
The Wilkes Land mass concentration (or mascon) is centered at 70°S 120°E / 70°S 120°E / -70; 120Coordinates: 70°S 120°E / 70°S 120°E / -70; 120 and was first reported at a conference in May 2006 by a team of researchers led by Ralph von Frese and Laramie Potts of Ohio State University,. The team used gravity measurements by NASA’s GRACE satellites to identify a 300 km (200 mi) wide mass concentration and noted that this mass anomaly is centered within a larger ring-like structure visible in radar images of the land surface beneath the Antarctic ice cap. This combination suggested to them that the feature may mark the site of a 480 km (300 mi) wide impact crater buried beneath the ice.
New details on the east Antarctic gravity field from the Gravity Recovery and Climate Experiment (GRACE) mission reveal a prominent positive free-air gravity anomaly over a roughly 500-km diameter subglacial basin centered on (70°S, 120°E) in north central Wilkes Land. This regional inverse correlation between topography and gravity is quantitatively consistent with thinned crust from a giant meteorite impact underlain by an isostatically disturbed mantle plug.