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Re: SNC Meteorite Origins
Hi Bernd and all,
If I read this right they are suggesting a single impact on Mars for the
origin of all of the Mars Meteorites. Just fairly recently
Dr. Lipschutz did a paper on the SNCs that suggest not only have collisions
delivered material from Mars, that some if not all of the meteorites are
unique and do a sampling of the different areas on Mars. I'll post the
paper here on this for your reading pleasure.
Martian Meteorites Provide
Glimpse Inside Red Planet
Purdue
University
CONTACT:
Lipschutz
Compiled by Amanda Siegfried
e-mail: rnapuml@vm.cc.purdue.edue-mail:
amanda_siegfried@uns.purdue.edu
Purdue News Service: (765) 494-2096; e-mail:
purduenews@uns.purdue.edu
August 4, 1998
WEST LAFAYETTE, Ind. -- Though scientists can't trace Martian meteorites
back to their specific sites on the
Red Planet, a Purdue University study shows that the travelers contain more
chemical clues to the location and
history of their native neighborhoods than originally expected.
Michael Lipschutz, professor of chemistry, analyzed the trace element
content of the 12 meteorites that are known
to have originated from Mars and found that the rocky fragments came from
six different regions below the
surface of the planet. He also found that each of the six regions operated
as a "closed system," blocking the transfer
of materials such as dust and vapor between regions.
"Since even vapor transfer did not occur between the regions, the
composition of each Martian meteorite can be
considered an accurate reflection of its source region, and therefore can
provide detailed information on each
region's location and history," Lipschutz says.
The study was published in the July issue of Meteoritics and Planetary
Science, which focused on the Martian
meteorites. Lipschutz also wrote the chapter on meteorites for the
40-chapter Encyclopedia of the Solar System,
which will be available in August.
Based on concentrations of 15 volatile trace elements, which are the
chemical elements most likely to condense
last as the planet solidified from a cloud of dust and gas, Lipschutz was
able to divide the meteorites into six major
groups from as many different parent regions.
He then compared the groupings to previous studies that had divided the
meteorites into six classifications based
upon other chemical contents and markers.
Because the groupings were virtually identical -- a finding that indicated
that the trace elements were intact and
had escaped contamination from outside influences -- Lipschutz says the
volatile chemical contents of the
meteorites can serve as reliable markers to assess information on their
thermal histories.
"These rocks provide samples from and glimpses into six chambers within the
Martian mantle," Lipschutz says.
"Each of the 12 Martian meteorites appears to have crystallized in a
location deep within the planet, and was
excavated only when its chamber was opened by an impact." Lipschutz says it
is unusual to find samples where
the chemical markers are so well preserved.
"The amazing thing is that whatever chemical and geological events Mars
experienced through time, all of the
elements -- volatile or not -- were able to remain intact," Lipschutz says.
"This is unlike the situation in other
extraterrestrial bodies, such as the Moon and many asteroids, where heating
caused by events such as the shock
of an impact can vaporize the volatile elements and destroy evidence of
past events."
Further studies may help pinpoint the location of each of the regions, and
could shed light on Mars' geological
history, Lipschutz says. His study was funded by the National Aeronautics
and Space Administration's (NASA)
Cosmochemistry program.
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