British Impact Crater
Thursday, 27. March 2008, 14:10:46
Ken Amor of Oxford University believes that a large meteorite (at least 500 meters in diameter) hit Northwest Scotland in the Precambrian about 1.2 billion years ago near the Scottish town of Ullapool. A report of the research, 'A Precambrian proximal ejecta blanket from Scotland' is published in the journal Geology.
Previously it was thought that unusual rock formations in the area had been formed by volcanic activity. But, the team lead by Amor found evidence buried in a layer of rock which they now believe is the ejected material thrown out during the formation of a meteorite crater. Ejected material from the huge meteorite strike is scattered over an area about 50 kilometres across, roughly centred on the northern town of Ullapool. The actual meteorite crater is thought to lie within the immediate vicinity, buried under younger rocks.
In the rocks they found the characteristic signature of meteoritic material, which has high levels of the key element iridium, normally only found in low concentrations in surface rocks on Earth. They found more evidence when they examined the rocks under a microscope; tell-tale microscopic parallel fractures that also imply a meteorite strike. Shocked quartz and biotite provide evidence for high-pressure shock metamorphism, while chromium isotope values and elevated abundances of platinum group metals and siderophile elements indicate addition of meteoritic material. The ejecta blanket reaches more than 20 m in thickness. Field observations suggest that the deposit was emplaced as a single fluidized flow that formed as a result of an impact into water-saturated sediments.
So far it is the largest meteorite strike known in the British Isles. There are about 174 known impact craters or their remnants on Earth.
This is the most spectacular evidence for a meteorite impact within the British Isles found to date.
• http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2FG24454A.1
• http://www.abdn.ac.uk/mediareleases/release.php?id=1275
• http://news.bbc.co.uk/2/hi/science/nature/7314329.stm
• http://news.softpedia.com/news/UK-039-s-Biggest-Meteorite-Impact-Discovered-81720.shtml
• http://www.inform.kz/showarticle.php?lang=eng&id=162214
PS of 30 March 2008
Hypocentre has some images here.
Previously it was thought that unusual rock formations in the area had been formed by volcanic activity. But, the team lead by Amor found evidence buried in a layer of rock which they now believe is the ejected material thrown out during the formation of a meteorite crater. Ejected material from the huge meteorite strike is scattered over an area about 50 kilometres across, roughly centred on the northern town of Ullapool. The actual meteorite crater is thought to lie within the immediate vicinity, buried under younger rocks.
In the rocks they found the characteristic signature of meteoritic material, which has high levels of the key element iridium, normally only found in low concentrations in surface rocks on Earth. They found more evidence when they examined the rocks under a microscope; tell-tale microscopic parallel fractures that also imply a meteorite strike. Shocked quartz and biotite provide evidence for high-pressure shock metamorphism, while chromium isotope values and elevated abundances of platinum group metals and siderophile elements indicate addition of meteoritic material. The ejecta blanket reaches more than 20 m in thickness. Field observations suggest that the deposit was emplaced as a single fluidized flow that formed as a result of an impact into water-saturated sediments.
So far it is the largest meteorite strike known in the British Isles. There are about 174 known impact craters or their remnants on Earth.
This is the most spectacular evidence for a meteorite impact within the British Isles found to date.
• http://www.gsajournals.org/perlserv/?request=get-abstract&doi=10.1130%2FG24454A.1
• http://www.abdn.ac.uk/mediareleases/release.php?id=1275
• http://news.bbc.co.uk/2/hi/science/nature/7314329.stm
• http://news.softpedia.com/news/UK-039-s-Biggest-Meteorite-Impact-Discovered-81720.shtml
• http://www.inform.kz/showarticle.php?lang=eng&id=162214
PS of 30 March 2008
Hypocentre has some images here.
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