All,
There are a number of recent articles (Kirschvink et al., 1997 comes
immediately to mind) suggesting large scale true polar wander (90 degrees in
15 million years). In essence, the entire lithosphere and mantle behave as
a single 'tectonic plate'. The 'plate' is driven by an interchange of
inertial moments (max becomes int, int becomes max). The net effect is to
align most of the mass along the equator. Therefore, if this idea is
correct, some continents would indeed flee from the poles at ~66 cm/yr. Of
course, there is some debate regarding the evidence proposed by Kirschvink
and colleagues, but it is an interesting idea. For contrasting viewpoints
see Torsvik et al., 1998; Meert, 1999; Torsvik and Rehnstrom, 2001.
Cheers
Joe Meert
----- Original Message -----
From: Eric Essene <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, June 02, 2001 6:35 PM
Subject: Re: Plate tectonics
> All,
> The reason I questioned the idea is that "pole flight" (migration
toward
> the equators) was one of the driving forces imagined by Wegener for
> continental drift. As I understand it, subsequent evaluation of the
forces
> involved led to a rejection of this as a significant factor. We need to
> hear from geodynamists on this topic.
> eric
>
>
> That is very interesting and not something I'd thought of before. If the
> >Earth's rotation affects the atmosphere why shouldn't it affect the
> >behaviour of the mantle as well? In advance of any hard data one way or
the
> >other, it seems a reasonable hypothesis that there should be some
influence.
> >
> >Roger Musson
> >
> >
> >-----Original Message-----
> >From: John Milsom [mailto:[log in to unmask]]
> >Sent: 01 June 2001 21:24
> >To: [log in to unmask]
> >Subject: Re: Plate tectonics
> >
> >
> >There IS an asymmetry. East facing subduction zones (western Pacific,
> >Caribbean, Scotia) seem to have a tendency to migrate outwards
> >('roll-back'). West facing zones (Pacific coasts of the Americas) seem to
> >be locked to their continental margins. First working hypothesis would be
> >that the asymmetry in the Earth's rotation (it goes one way, not the
other)
> >has something to do with it.
>
>
> Eric Essene
> Professor of Geology
> Department of Geological Sciences
> 2534 C.C. Little Bldg.
> 425 E. University Ave.
> University of Michigan
> Ann Arbor MI 48109-1063 USA
> fx: 734-763-4690
> ph: 734-764-8243
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