Re: BIG BANG IN ANTARCTICA -- KILLER CRATER FOUND UNDER ICE?


"George" <george@xxxxxxxxxxxxxxxxxxxxx> wrote in message news:xPKdnZEn49Q3fOLZRVn-tA@xxxxxxxxxxxxxxxx
http://researchnews.osu.edu/archive/erthboom.htm

COLUMBUS, Ohio -- Planetary scientists have found evidence of a meteor
impact much larger and earlier than the one that killed the dinosaurs -- an
impact that they believe caused the biggest mass extinction in Earth's
history.

The 300-mile-wide crater lies hidden more than a mile beneath the East
Antarctic Ice ***. And the gravity measurements that reveal its existence
suggest that it could date back about 250 million years -- the time of the
Permian-Triassic extinction, when almost all animal life on Earth died out.

I posted the following on sci.bio.evolution, but I will probably get more
informed responses here.
----
Hmmm. There has been debate for years as to whether the KT extinction
was caused by the Yucatan asteroid strike or by the volcanic activity
which created the Deccan traps, half-way around the globe.

Now we will have a debate as to whether the end-Permian extinction was
caused by the volcanism at the Siberian traps, or the impact in
Antarctica, half-way around the globe.

Does this strike anyone else as a surprising coincidence? As far as I
know, the Deccan and Siberian traps are the largest known lava flows in
the past 300 million years. And it appears that both were roughly
coincident in time with the two largest known impact events. In theory,
shock waves from the impact would spread horizontally, decreasing in
amplitude with distance, but then converging on the antipode. Converging
to a focus? It sounds crazy, and probably IS crazy, but I can't help
but wonder.
----
Since writing this, I have realized that the 250 million year date for
the impact is just a guess, but if it does turn out to be just before
the Siberian traps, then double 'Hmmmm'.

I seem to recall reading something about antipodal 'spalling' effects
from impacts on moons or asteroids or something. Can anyone provide a
link for that?


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