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Re: Vredefort

At 07:05 AM 11/25/99 -0500, Larry Febo wrote: 
>> -----Original Message-----
>> Ilja Nieuland wrote:
>> Brings me to another thought that keeps occurring (...more wild
>> speculation!???..8^). Perhaps some hardcore geologists out there can set me
>> straight. Could some of the larger meteor strikes that have occurred in the
>> past be a significant cause of magma currents that power plate tectonics? I
>> know that internal release of radioactivity is supposed to be the cause, but
>> couldn`t a large (fast moving) meteor strike penetrate into the deep mantle
>> and cause long-term displacement of matter that would result in long term
>> reestablishment of equilibrium (as far as material density...similar to the
>> rise of ancient mountain roots). Could this be what powers plate tectonics?

Certainly a large enough impact could wreak havoc on the crust, and even
overturn large parts of the mantle.  No such impact has occurred in the last
3.5 billion years, of this we can be fairly certain.

However, as geologists have known about the impact that produced the Moon for
decades, I am sure they have taken that into consideration in modeling the
driving forces of plate tectonics.  So, it seems unlikely to me that this sort
of thing is the origin of the mantle circulation.

May the peace of God be with you.         sarima@ix.netcom.com