From: Technotranscendence (neptune@mars.superlink.net)
Date: Tue Jun 26 2001 - 17:56:04 MDT
On Tuesday, June 26, 2001 12:01 PM Mike Lorrey mlorrey@datamann.com wrote:
> THe fact that this layer also has a significant iridium layer says it
> cannot be explained by volcanic activity.
I disagree. If my memory's correct, the amount of iridium is higher in the
mantle. So, volcanic activity could enrich the crust with iridium. If
that's so, massive eruptions, such as the Deccan Traps, might possible be a
source for such iridium at the K/T boundary.
Now, this only means there's an alternative explanation, not that it is the
case. Personally, I believe the iridium layer came from an impact, but my
belief is not 100%... Granted, too, I'm no expert here.:) (I'm also not
going to suffer insomnia regarding my uncertainty in this area.:)
> > > An interesting point is that the end-
> > > Cretaceous and end-Permian extinction match up with
> > > *both* massive bolide impacts *and* bogglingly large
> > > flood basalts.
> >
> > Yeap. Archibald does not dispute this, though there is some
disagreement
> > over timing. On page 145 of the book, he even charts the level of
eruption,
> > but argues on 144 that the "eruptions... were episodic -- not
continuous."
> > The flood basalts range in age from 69 to 65 million years old. If the
> > impact is placed at 65 million years ago, this means a good portion of
high
> > level volcanic activity was already happening before the impact. This
does
> > not completely rule out an impact as the [nonavian] dinosaur killer,
though
> > it might point to an accomplice.
>
> Significant volcanic activity would have resulted from a change in the
> orbit of the moon caused by the influence of a number of close flybys
> over several million years of the object that wound up colliding at 65
> million years. For example, an impact or flyby of the moon which would
> have caused it to either come closer to earth (increasing tidal stress
> but decreasing tortional stress on earth's rotational velocity) on a
> faster orbit or else move away from earth into a slower orbit (thus
> decreasing tidal stress but increasing tortional stress on earth's
> rotational velocity) would have significantly affected tectonic forces
> during that period. Also a change in the moon's angle of inclination
> would have caused similar release of tectonic forces.
Is there any proof that this is the case? I know the Earth's Moon has
changed position during its career and continues to do so, but isn't the
effect very gradual and why would the K/T boundary be a time when a
spectacular change happened? (I'm not being sarcastic here, just asking...)
> If the body that impacted the Yucatan was a fragment of a calved body
> that impacted or grazed the moon on previous occasion, this would
> explain the time disparity.
That's a possibility. How would we test it? Has anyone pointed to a
smoking gun on the Moon -- such as a crater that would meet certain age
requirements? My guess would be the Deccan Traps establish a date for such
a calving at 69 million years ago or thereabouts.
Cheers!
Daniel Ust
http://uweb.superlink.net/neptune/
Check out "Free trade and the climb out of poverty" by Steven Horowitz at:
http://www.liberzine.com/stevenhorowitz/010506ftaa.htm
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