Meteorite Crater In Greenland Called World's Oldest, Biggest

A 100 kilometre-wide crater has been found in Greenland, the result of a massive asteroid impact a billion years before any other known collision on Earth.

The previously oldest known crater on Earth formed two billion years ago and the chances of finding an even older impact were thought to be astronomically low.

Now, a team of scientists from the Geological Survey of Denmark and Greenland (GEUS) in Copenhagen, Cardiff University in Wales, Lund University in Sweden and the Institute of Planetary Science in Moscow has upset these odds.


The spectacular craters on the Moon formed from impacts with asteroids and comets betweenthree3 and four billion years ago.
The early Earth, with its far greater gravitational mass, must have experienced even more collisions at this time - but the evidence has been eroded away or covered by younger rocks.
Following a detailed programme of fieldwork, funded by GEUS and the Danish ‘Carlsbergfondet’ (Carlsberg Foundation), the team have discovered the remains of a giant three billion-year-old impact near the Maniitsoq region of West Greenland.


'This single discovery means that we can study the effects of cratering on the Earth nearly a billion years further back in time than was possible before,” according to Dr Iain McDonald of Cardiff University’s School of Earth and Ocean Sciences, who was part of the team.

It is possible or even likely that the meteorite hit the sea, for the preserved rocks have been intensely altered by circulating hot aqueus fluids. These fluids were likely derived from sea water that would have been able to penetrate deep into the Earth's crust through the numerous fissures and crush zones generated by the impact.

Boris A. Ivanov at the Institute of Planetary Science, Russian Academy of Science, Moscow, has carried out a series of provisional model calculations, which suggest that the impacting meteorite at Maniitsoq may have had a diameter of more than 30 km, i.e., about twice the size of the Vredefort meteorite and with a mass about ten times larger.

If this meteorite had hit the Moon, the final crater structure would have had a diameter well above 1000km and easily visible from Earth. However, due to the much stronger gravity of our planet, the Maniitsoq structure may have had a diameter of 'only' some 500-600km.


If an impact of this size hit the Earth today, it would not only be able to pulverise a medium-sized national state but its global effects would also kill all higher life.

Then, three billion years ago, there was not much life to extinguish, but as yet no depositional rocks of matching age have yet been identified that could enlighten the effects of the Maniitsoq impact such as extreme tsunamis, deposition of re-condensated atmospheric glass particles from the evaporated meteorite or other signs of global atmospheric and marine effects.

Finding the evidence was made all the harder because there is no obvious bowl-shaped crater left to find. Over the three billion years since the impact, the land has been eroded down to expose deeper crust 25km below the original surface.   (dailymail.co.uk)