Impact Down UnderIt’s no surprise to find old craters and scars of meteorite impacts in the vast lan

Impact Down UnderIt’s no surprise to find old craters and scars of meteorite impacts in the vast lands of the Australian outback. The land here is flat, very old and largely tectonically inactive, but to find two scars that are thought to be the worlds most massive impact site is a double whammy.There has been quite some controversy over a recent discovery made by a team of Geophysicists while drilling for geothermal research in central Australia.This 300+ million year old impact site, suggested by the team, is thought to have been created by not one but two strikes. While the impact sites are not visible on the surface, the evidence of a 400 kilometre (248 mile) wide impact zone was found about 3km (1.9m) beneath the Earth’s crust.While the team are convinced that their findings suggest that this is the zone of the world’s largest ever impact site, others are not so convinced. The craters are deeply buried and their outlines are only recognized as changes in the gravity, as seen in this map, which can be produced in several ways including by plate tectonic processes.Furthermore, the shape of the gravity anomalies isn’t perfectly round as some craters are - this could be the result of 2 craters forming at the same time or an indication that this is a larger tectonic feature.The main evidence for these rocks being produced by impact is changes in the structure of quartz grains known as Planar Deformation Features. The team identified several examples of PDFs from these sites, but compared to other impact structures they are less straight and possibly more altered. That could indicate that these quartz grains were altered in a different way, or it could be a consequence of the craters adjusting and deforming after they were formed.The team who discovered the site previously in 2010 has carried out further investigation, which revealed a second zone that they suspect is a second impact dated around the same time as the first. They have suggested that the same meteorite created this but that it had split into two pieces before impact.Something this size would almost certainly have caused some kind of ecological impact and many species would have died as the result, yet no evidence has been found to confirm that any such event has happened.Strike one… strike two… you’re out? Check out the links and decide for yourself. This will be something interesting to keep an eye on as further investigation is carried out.~ JMImage Credit: http://bit.ly/1OyHYOwMore Info:World’s largest asteroid impact found:http://bit.ly/1OyHYOwMeteorite Craters in Australia: http://bit.ly/1bs5YDSHints of buried impact craters: (the controversy)http://bit.ly/19Pggh0Giant asteroid impact found in Australia, 2010:http://bit.ly/1BLSO9M[__](https://www.facebook.com/TheEarthStory/photos/a.352867368107647/853498971377815/?type=1&theater#) -- source link

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