It looks like you're using an Ad Blocker.
Please white-list or disable AboveTopSecret.com in your ad-blocking tool.
Some features of ATS will be disabled while you continue to use an ad-blocker.
It’s now a minimum of 200 kilometers, this makes it about the third biggest anywhere in the world.
Glikson and others believe the impact was felt across the world, changing life’s course and spewing a blanket of ash into the atmosphere that blanketed out the sun. “It’s likely to be part of a particular cluster that was linked with a mass extinction at that time,” he told the Conversation.
But dating it has been difficult. Glikson thinks it hit at least 300 million years ago, but “it’s a mystery,” he said. “We can’t find an extinction event that matches these collisions.”
originally posted by: FamCore
a reply to: nighthawk1954
I'm going to go out on a limb here and say that (if there was life at the time) this was an ELE (extinction level event).
It doesn't sound like the largest in the world and not even the largest in Australia, unless they mean the largest confirmed but since he's not even dated the impact it doesn't sound very confirmed. This one sounds larger:
originally posted by: nighthawk1954
The crater from the impact millions of years ago has long disappeared. But a team of geophysicists has found the twin scars of the impacts – the largest impact zone ever found on Earth – hidden deep in the earth’s crust.
600km is greater than 400km but I think more research is needed on both impacts.
The Massive Australian Precambrian/Cambrian Impact Structure also known as MAPCIS is a proposed impact structure based upon arguments presented by Daniel P. Connelly at Geological Society of America meetings. Its center is located approximately equidistant between Uluru (Ayers Rock) and Mount Conner in Australias' Northern Territory. A hypothetical outermost ring is 2,000 kilometres (1,200 mi) in diameter is claimed to be the result of undefined "far field stresses." The crater itself is smaller at approximately 600 km (370 mi) in diameter. Connelly argues that the age of this hypothetical impact is approximately 545 mya which puts it near the end of the Neoproterozoic Era. If confirmed as an impact crater, it would be the largest on earth.
It apparently shows confirmed impacts. The Wiki on Australian Impacts has two lists, confirmed and unconfirmed.
originally posted by: Saint Exupery
Here's a good listing of known Earth impacts. If it's not up-to-date, it's close to it.
Earth Impact Database
Michael Davias, Stamford, CT and Thomas Harris, Lockheed-Martin (Retired), Orbit Operations, Valley Forge, PA
Pleistocene Epoch cosmic impacts have been implicated in the geomorphology of two enigmatic events. Remarkably, in both cases spirited debates remain unsettled after nearly 100 years of extensive research. Consensus opinion holds that the Australasian (AA) tektites are of terrestrial origin despite the failure to locate the putative crater, while a cosmic link to the Carolina bays is considered soundly falsified by the very same lack of a crater. Likely >100 km in diameter, these impacts during geologically recent times should be readily detectable on the Earth’s surface. The improbability that two craters have eluded detection informs a hypothesis that a single impact at ~786 ka generated AA tektites as distal ejecta and Carolina bays as progeny of proximal ejecta. The AA astroblem search is focused on SE Asia despite a strewn field encompassing >30% of the Earth’s surface. This spatial scope implies to us that interhemispheric transits should be considered, as does findings that AA tektites were solidified in a vacuum, then ablated on re-entry at ~10 km sec-1. A Coriolis-aware triangulation network operating on the orientations of 44,000 Carolina bays indicates a focus near 43ºN, 84ºW. Referencing the work of Urey and Lin, we propose that a near-tangential strike to the Earth’s limb generated the 150 x 300 km oval depression that excises Saginaw Bay and opens Michigan’s Thumb. That region was likely buried under deep MIS 19 Laurentide ice at 786 ka. Schultz has shown that oblique impacts into continental ice sheets yield non-traditional astroblems, and multiple glaciations have since reworked this site, making identification more challenging. Hypervelocity gun tests show that oblique impacts produce a vertical plume of ejecta, biased slightly down-range. Ballistic trajectories reflecting such a plume deliver tektites to all AA finds when lofted at ~10 km sec-1 and parameterized with the proposed depression’s location and 222º azimuth. Chemical and isotopic characteristics of AA tektites suggest they were sourced from sandstone and greywacke of Mesozoic age, which is congruent with Michigan Basin strata lost when The Thumb developed. The distribution of proximal ejecta may explain anomalous pulses of regolith in moraines and sediment loading in regional drainage basins recently dated ~800 ka using 10Be/26Al methods.