[meteorite-list] Meteor crater impact site : Greenland

[sbdeboer]

Ancient Greenland meteor crater good news for Canadian nickel miner
By Randy Boswell, Postmedia NewsJuly 5, 2012
)

The discovery of the oldest known meteorite impact crater on Earth - a
vanishingly faint, 100-km wide impression in southwest Greenland created by
a colossal space rock at least three billion years ago - could prove to be a
bonanza for the Canadian nickel-mining company with exploration rights at
the site.
Photograph by: Bob Strong , Reuters
The discovery of the oldest known meteorite impact crater on Earth - a
vanishingly faint, 100-km wide impression in southwest Greenland created by
a colossal space rock at least three billion years ago - could prove to be a
bonanza for the Canadian nickel-mining company with exploration rights at
the site.
As with the famed Nickel Belt around Sudbury, Ont. - the world's only other
known location in which nickel-rich rock is associated with a major
extraterrestrial impact - confirmation of the Greenland crater means the
valuable metal was likely melted, concentrated and forced to the surface by
the ancient meteorite strike, potentially forming huge and easy-to-extract
deposits.
It's a prospect that Vancouver-based North American Nickel Inc. - already a
major player in the Sudbury area - said in a statement last year would, if
proven, add "tremendous upside potential" to its Maniitsoq project, which
encompasses the Greenland impact site.
And in the wake of last week's announcement that a team of European
researchers has verified the impact hypothesis, the company's chief
geologist, John Pattison, told Postmedia News on Thursday that, "We're very
excited about it.
"The source of nickel on Earth is ultimately the mantle," he added,
referring to the inner layer of planet that typically lies about 25
kilometres below the exposed crust. "So anything that can get that nickel
from the mantle up into the crust is a good thing when you're looking for
nickel deposits."
The Greenland discovery - detailed in the latest issue of the journal Earth
and Planetary Science Letters by a group of scientists from Denmark, Sweden,
Russia and Britain - pushes back by a startling one billion years the age of
the earliest known impact crater on Earth.
Located near the coastal Greenlandic community of Maniitsoq, directly across
the Davis Strait from Nunavut's Baffin Island, the site has undergone so
many geological changes over the past three billion years that there is "no
obvious bowl-shaped crater left to find" at the surface, the researchers
state in a summary of the study.
But after three years of "painstaking" analysis of unusual rock formations
in the region, the team concluded there could be no other explanation for
the features than the explosive force of a massive meteorite - up to 30
kilometres across - at a time when life on Earth was only beginning to take
shape.
"If an impact of this size hit the Earth today, it would not only be able to
pulverize a medium-sized national state, but its global effects would also
kill all higher life," the Geological Survey of Denmark and Greenland stated
in an overview of the discovery.
The task of confirming the ancient impact "was rather like a Sherlock Holmes
story," noted Cardiff University geologist Iain McDonald, a member of the
discovery team. "We eliminated the impossible in terms of any conventional
terrestrial processes, and were left with a giant impact as the only
explanation for all of the facts."
McDonald added that the geologists around the world were initially skeptical
that a three-billion-year-old crater could be identified.
"It has taken us nearly three years to convince our peers in the scientific
community of this, but the mining industry was far more receptive," said
McDonald, referring to North American Nickel's growing interest in the site.
Adam Garde, a researcher with the Copenhagen-based survey and lead author of
the study, told Postmedia News that the Maniitsoq crater is much older and
more deformed by time than the famous one at Sudbury, which is "preserved in
a much more pristine state closer to the original surface of the Earth."
But he added: "Mantle rocks are richer in nickel than most normal crustal
rocks, and if that nickel could somehow be concentrated during the
emplacement into the crust or subsequently, this could be interesting for a
mining company."
Pattison said the research team's confirmation of the impact theory could
alter North American Nickel's strategy for identifying potential mine sites
at Maniitsoq, which began in earnest last week with helicopter flights over
the region.
He said the way the "nickel-rich magma" reaches the surface would be
controlled by the direction and force of the meteorite strike, and finding
the best metal deposits will mean "looking at it from an impact point of
view."


Read more:
http://www.canada.com/Ancient+Greenland+crater+find+good+news+Canadian+nicke
l+miner/6890084/story.html#ixzz1zy3f4r6F