[meteorite-list] Meteor Impacts: Life's Jump Starter?

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Mon Aug 8 13:31:47 2005
Message-ID: <200508081730.j78HUoU00761_at_zagami.jpl.nasa.gov>

http://www.geosociety.org/news/pr/05-25.htm

Geological Society of America News Release

8 August 2005
GSA Release No. 05-25

Contact: Ann Cairns, acairns_at_geosociety.org
Director - Communications and Marketing
(303) 357-1056, fax 303-357-1074

Meteor Impacts: Life's Jump Starter?

Meteor impacts are generally regarded as monstrous killers and one of
the causes of mass extinctions throughout the history of life. But there
is a chance the heavy bombardment of Earth by meteors during the
planet's youth actually spurred early life on our planet, say Canadian
geologists.

A study of the Haughton Impact Crater on Devon Island, in the Canadian
Arctic, has revealed some very life-friendly features at ground zero.
These include hydrothermal systems, blasted rocks that are easier for
microbes to inhabit, plus the cozy, protected basin created by the
crater itself. If true, impact craters could represent some of the best
sites to look for signs of past or present life on Mars and other planets.

A presentation on the biological effects of impacts is scheduled for
Monday, 8 August, at Earth System Processes 2, a meeting co-convened by
the Geological Society of America and Geological Association of Canada
this week in Calgary, Alberta, Canada.

The idea that meteor impacts could benefit or even create conditions
suitable for the beginning of early life struck Canadian Space Agency
geologist Gordon Osinski while he and colleagues were conducting a
geological survey of the 24-kilometer (15-mile) diameter Haughton
Crater. Along the rim of the crater they noticed what looked like
fossilized hydrothermal pipes, a few meters in diameter.

"That set the bells ringing about possible biological implications,"
said Osinski. Hydrothermal systems are thought by many people to be the
favourable places for life to evolve."

Detailed mineralogical analyses have since revealed that when the
Haughton meteor smacked into the icy ground 23 million years ago it
created not only a crater, but fractured the ground in such a way as to
create a system of steamy hydrothermal springs reaching temperatures of
250 degrees C. The heat appears to have gradually dropped over a period
of tens of thousands of years, the researchers report.

Besides providing heat and cracking the ground, the impact also created
pore spaces in otherwise dense granitic rocks, giving microbes more
access to the minerals and the surfaces inside the rocks - basically
more real estate and more supplies.

The shocked rocks are also more translucent, which would be beneficial
to organisms that possessing with any photosynthetic capabilities.

A crater shape itself also might serve as a protective environment, says
Osinski. As such, impact craters are also good places to store evidence
of past life. On Earth many craters fill with water and become lakes.
Lakes accumulate sediments, the layers of which are a geological archive
of the time after the crater formed. The Haughton Impact crater, for
instance, contains the only Miocene-age sediments in the entire Canadian
Arctic.

"One of the most interesting aspects of the Haughton Impact Crater is
that it's in a polar desert," said Osinski. The dry, frigid weather
makes for a barren landscape that's easy to study, he said. The same
features make it one of the more Mars-like places on Earth.

"Most people put impacts with mass extinctions," said Osinski. "What
we're trying to say is that following the impact, the impact sites are
actually more favorable to life than the surrounding terrain."

It's interesting to note, says Osinski, that on Earth the heaviest
meteor bombardment of the planet happened at about the same time as life
is believed to have started: around 3.8 billion years ago. Impact
craters of that age were long ago erased on Earth by erosion, volcanic
resurfacing and plate tectonics.

But other planets and moons - including Mars - still bear the cosmic
scars of that early debris-clogged period in the solar system. It may be
possible, therefore, that the best places to look for at least fossil
evidence of life on Mars is inside those very same craters, he said.

"What we're doing is trying to narrow down the search area," said Osinski.

Impact Craters as Habitats for Life on Early Earth and Mars
Monday, 8 August, 9:20 am MDT
Eau Claire North/South, Calgary Westin Hotel
Abstract may be viewed at
http://gsa.confex.com/gsa/2005ESP/finalprogram/abstract_88952.htm

      
CONTACT INFORMATION:

During the Earth System Processes 2 meeting, 8-11 August, contact
Ann Cairns at the ESP2 NewsroomCalgary Westin Hotelfor assistance
and to arrange for interviews: +1-403-508-5135After the meeting, contact:
Canadian Space Agency Media Relations: +1-450-926-4370, www.space.gc.ca
Received on Mon 08 Aug 2005 01:30:48 PM PDT