New Tectonic theory
alin...@my-deja.com
claims gives a better match reconstructing
Pangaea and that it also gives a better
explanation regarding the large sizes of the
dinosaurs.
The following is an outline of a new Tectonic
theory that can explain the expansion of the
Earth, the increase in mass, the formation of
mountains around continents and the breaking up
of Pangaea in a better way than Global Expansion
Tectonics.
How come Pangaea broke up suddenly ca 280 Ma?
Earth crust formed almost 4000 Ma suddenly broke
up. Why not before? Compare the age of the
continental crust with the oceanic crust; a
steady 4000 Ma against 200 Ma and younger.
The answer could be a catastrophic event.
Take a globe model of the Earth and turn it so
that you have the center of the Pacific Ocean
pointing at you. You are now looking at the
worlds largest impact crater – resulting from a
twin planet system colliding ca 280 Ma. Today’s
plate movements are only repercussions resulting
from this cataclysm.
The Gutenberg discontinuity marks the boundary of
the Earth 280 Ma. This means that the core of the
present Earth actually is the old Earth with 6960
km radius, about 55 % of today’s radius.
So the present core is the old Earth. The
continental crust, composed of less dense matter,
was peeled off during impact and became a
floating island on the new planet. This island
was the supercontinent we call Pangaea, albeit in
a cracked up state.
This means that the sister planet was much bigger
than the old Earth, maybe with an atmosphere of
its own just like old Earth, the other twin
planet. If the sister planet was a water planet
it could explain where the ocean water came from.
The bigger sister planet could have been entirely
covered with water with a thin oceanic crust,
consisting mostly of basaltic rock, that was
shattered by the impact and flooded by magma so
that no trace of it is left today.
The Pacific Ocean is the best candidate for the
impact crater, or rather, the impact area since
the old Earth became embedded in the larger
sister planet. Take a look at the continents
around the Pacific Ocean – mountain chains all
around. These mountains around the Pacific Ocean
was formed during the collision and marks the rim
of the impact area.
The time for when Pangaea broke up could be other
than 280 Ma. Even two cataclysmic events are
possible. The outer core could be the old Earth
and the inner core one of its moons, indicating
two cataclysmic events.
The new theory does not replace current Plate
Tectonic theories, just adds to the overall
picture. The breaking up of Pangaea does not
replace the continental drift. Take for example
the reconstruction of the Godswana
supercontinent. Notice that this reconstruction
does not include any continental margin around
the Pacific Ocean. If, on the other hand, a
similar reconstruction and equally good match
could be made with continental margins around the
Pacific Ocean, then we would have to find another
candidate for the impact area.
However, the new theory gives a different
explanation about the formation of mountains
compared to traditional Plate Tectonic theories.
Sent via Deja.com http://www.deja.com/
Before you buy.
alin...@my-deja.com
reconstructing Pangaea on a globe with half the radius of present
Earth. Also, that a turning, cooling planet is not likely to develop a
lopsided crust. If these statements are true, they are serious
oppositions to current plate tectonics.
The following outline of a new tectonic theory explains how the
continental crust once could have covered the entire surface of the
Earth without depending on new physical theories such as matter
creation needed in some global expansion theories.
How come Pangaea broke up suddenly ca 280 Ma? Earth crust formed almost
4000 Ma suddenly broke up. Why not before? Compare the age of the
continental crust with the oceanic crust; a steady 4000 Ma against 200
Ma and younger. Why was not the continental crust created evenly around
the entire globe, like on the moon where the entire crust is 4000+ Ma,
but only on about 30 % of its surface?
The answer could be a catastrophic event.
Take a globe model of the Earth and turn it so that you have the center
of the Pacific Ocean pointing at you. You are now looking at the worlds
largest impact crater – resulting from a twin planet system colliding
ca 280 Ma. Today’s plate movements are only repercussions resulting
from this cataclysm.
The Gutenberg discontinuity marks the boundary of the Earth 280 Ma.
This means that the core of the present Earth actually is the old Earth
with 6960 km radius, about 55 % of today’s radius.
So the present core is the old Earth. The continental crust, composed
of less dense matter, was peeled off during impact and became a
floating island on the new planet. This island was the supercontinent
we call Pangaea, albeit in a cracked up state.
This means that the sister planet was much bigger than the old Earth,
maybe with an atmosphere of its own. If the sister planet was a water
planet it could explain where the ocean water came from. The bigger
sister planet could have been entirely covered with water with a thin
oceanic crust, consisting mostly of basaltic rock, that was shattered
by the impact and flooded by magma so that no trace of it is left
today.
A meltdown only happened in the oceanic crust of the sister planet,
very much like the plate tectonic subduction of today but on a much
larger scale. The continental crust of the old Earth probably stayed
intact, except for cracks and new mountains resulting from the
collision, and instead of covering 100% of a planet’s surface it now
became to cover only about 30% of the newly assembled planet - the
Earth of today.
The Pacific Ocean is the best candidate for the impact crater, or
rather, the impact area since the old Earth became embedded in the
larger sister planet. Take a look at the continents around the Pacific
Ocean – mountain chains all around. These mountains around the Pacific
Ocean was formed during the collision and marks the rim of the impact
area. Around no other ocean do we find continuos mountain formations
like this.
The time for when Pangaea broke up could be other than 280 Ma, maybe as
far back as 800 Ma. Even two cataclysmic events are possible. The outer
core could be the old Earth and the inner core one of its moons,
indicating two cataclysmic events. This means that almost all tectonic
theories, such as continental drift and sea floor spreading, still
could give the best description of a post-cataclysmic Earth. The new
theory does not replace current plate tectonic theories, just adds to
the overall picture.
The breaking up of Pangaea does not replace the continental drift. Take
for example the reconstruction of the Godswana supercontinent. Notice
that this reconstruction does not include any continental margin around
the Pacific Ocean. If, on the other hand, a similar reconstruction and
equally good match could be made with continental margins around the
Pacific Ocean, then we would have to find another candidate for the
impact area.
However, the new theory gives a different explanation about the
formation of mountains compared to traditional plate tectonic theories.
I.e. the formation of mountains around the Pacific Ocean is a result
from a cataclysmic event and not built-up by the processes proposed in
current plate tectonic theories.
There is reasonable evidence that the solar system once contained more
planets than today, in fact a very large number of planets is believed
to have existed, and that the planets today are the results of
accretion. In the light of this, twin planet systems seem likely to
have existed back in the history of our solar system. And collisions:
giant liquid spheres with thin crusts slowly melting together.
I am a computer scientist and geology is not my field, and I would like
someone working in the field of geology to take a look at this outline
of a new tectonic theory.
Christine Wells
Been there, discussed this, got the fridge magnet, the floppy hat and the
bloody T shirt!
Chris. ( grrrrrrrrr)
<alin...@my-deja.com> wrote in message news:8tecmi$es5$1...@nnrp1.deja.com...
> Global Expansion Tectonics is a theory that some
> claims gives a better match reconstructing
> Pangaea and that it also gives a better
> explanation regarding the large sizes of the
> dinosaurs.
>
> The following is an outline of a new Tectonic
> theory that can explain the expansion of the
> Earth, the increase in mass, the formation of
> mountains around continents and the breaking up
> of Pangaea in a better way than Global Expansion
> Tectonics.
>
> How come Pangaea broke up suddenly ca 280 Ma?
> Earth crust formed almost 4000 Ma suddenly broke
> up. Why not before? Compare the age of the
> continental crust with the oceanic crust; a
> steady 4000 Ma against 200 Ma and younger.
>
> The answer could be a catastrophic event.
>
> Take a globe model of the Earth and turn it so
> that you have the center of the Pacific Ocean
> pointing at you. You are now looking at the
> worlds largest impact crater - resulting from a
> around the Pacific Ocean - mountain chains all
Barbara Hughes
post thread on an expanding earth! Been there, read that.
Barbara
Mitchell Isaacs
news:8tjvq5$gks$1...@lure.pipex.net...
> Another load of codswallop!
>
> Been there, discussed this, got the fridge magnet, the floppy hat and the
> bloody T shirt!
Mitchell
alin...@my-deja.com
posted it here.
/Anders
In article <5688-39...@storefull-286.iap.bryant.webtv.net>,
Don Quixote
<alin...@my-deja.com> wrote in message news:8tkce6$s72$1...@nnrp1.deja.com...
> Sorry about that. I could not find a similar theory on the Web so I
> posted it here.
Go to the *google* search engine and plug in "Expanding Earth"... I just got
1,280 hits. Then you can read to you heart's content.
Then go to *google* and plug in "Plate Tectonics" and read what those sites
have to say, and see how the PT theory fits nearly all known geology and
geophysics.
Then go to Deja and search for recent threads in this newsgroup on
"Expanding Earth". None of what you propose is *new*, has been discussed,
argued and ranted about in here for a long, long time, and has been fairly
well dismissed by observable fact.
Please look at the data you can find in these searches mentioned above.
--
DQ.
alin...@my-deja.com
of an expanding Earth, both on the Web and in the news groups. But I
haven't found anything near the theory I propose. I have received
several e-mails from geologists and none of them tells me that this
theory has already been considered.
Could you please point me to a source that describes a similar theory,
because I can't find any.
/Anders
ara...@my-deja.com
alin...@my-deja.com wrote:
> I have already done that. And, sure, I did find a lot about the theory
> of an expanding Earth, both on the Web and in the news groups. But I
> haven't found anything near the theory I propose. I have received
> several e-mails from geologists and none of them tells me that this
> theory has already been considered.
>
> Could you please point me to a source that describes a similar theory,
> because I can't find any.
I am a geologist and have read the idea you have proposed and it does
not not describe observable or experimental geology. There is no need
to propose any catastrophic event to explain all observable
macrogeology. First of all there is ample evidence of plate tectonic
activity through to the early proterozoic and particular exotic
accretionary terranes. In my part of the world (Australia) have a look
at the Narrier Belt, the Kimberley and the Albany-Fraser block. ALmost
all ordovician to Silurian island arc volcanics belts that dominate the
eastern half of the continent - also accretionary material.
Secondly continental silalic crust can easily be explained through
processes of differentiation of a primarily dunitic upper mantle to form
bimodal basaltic and acidic volcanism and a peridotitic lower crust.
If you have taken to trouble to go out and study geology from the
Archaean through to the present you would see that the concept of
catastrophic geological events are a direct result of a lack of
understanding and/or the willingness to study the discipline. There is
nothing better than standing 12,000 feet underground looking up at
Archaean load cast and ripples draped with gold to see that very little
has changed in geological processes over the last 4,000,000,000 years.
Don Quixote
<alin...@my-deja.com> wrote in message news:8tknpa$71t$1...@nnrp1.deja.com...
> I have already done that. And, sure, I did find a lot about the theory
> of an expanding Earth, both on the Web and in the news groups. But I
> haven't found anything near the theory I propose. I have received
> several e-mails from geologists and none of them tells me that this
> theory has already been considered.
>
> Could you please point me to a source that describes a similar theory,
> because I can't find any.
>
> /Anders
>
I put "Impact Crater" into google and came up with 10,900 hits. Somewhere in
there is certainly a discussion of the Pacific Ocean as a possible impact
site. It has been proposed before. There is *someone* (can't remember who)
that post in here occasionally and proposes the Pacific basin as an impact
site that caused the present hot spot. See if you can find that with a Deja
search.
Since your theory is a variant of an Expanding Earth model you will need to
offer the data that falsifies the Plate Tectonic model, which is well
accepted, and well supported by observable and measurable geological and
geophysical data. I would suggest that you first need to become familiar
with magmatic differentiation so that you understand how continental crust
forms. Then you need to understand how mountains form from tectonic
stresses, and how mountains form from volcanic processes, and the
difference.
If you are to propose a new theory then it is incumbent upon you to provide
two things; the evidence that proves your theory and the evidence that
falsifies the presently accepted theory. Since Plate Tectonics is a
geological/geophysical model, what geological and geophysical evidence do
you put forth that falsifies the PT model? Since your proposed model is a
geological/geophysical model, what geological and geophysical evidence do
you need to present to prove your theory?
--
DQ
alin...@my-deja.com
could very well be a development of PT. There are several types of
mountains and maybe one or several of these types are the result of an
impact while other types has been created by plate tectonic processes.
I would be nice to do a computer simulation of the impact. Maybe
someone already have done one. Also, the atmosphere on Earth was
probably different before the impact. Maybe traces of this could be
found in some rock.
/Anders
alin...@my-deja.com
some mountains came from an impact. Other mountains could be the
results of plate tectonic processes. Apart from volcanoes, what kind of
mountains surrounds the Pacific Ocean?
/Anders
Don Quixote
<alin...@my-deja.com> wrote in message news:8tlnc8$174$1...@nnrp1.deja.com...
> The new theory does not necessarily contradict plate tectonics. It
> could very well be a development of PT. There are several types of
> mountains and maybe one or several of these types are the result of an
> impact while other types has been created by plate tectonic processes.
>
> I would be nice to do a computer simulation of the impact. Maybe
> someone already have done one. Also, the atmosphere on Earth was
> probably different before the impact. Maybe traces of this could be
> found in some rock.
>
> /Anders
>
Whoa! Wait one moment... In your initial post announcing this new tectonic
model you said:
> Take a globe model of the Earth and turn it so
> that you have the center of the Pacific Ocean
> pointing at you. You are now looking at the
> worlds largest impact crater - resulting from a
> twin planet system colliding ca 280 Ma. Today's
> plate movements are only repercussions resulting
> from this cataclysm.
And now you say:
>The new theory does not necessarily contradict plate tectonics. It
> could very well be a development of PT.
How did PT cause [sic] (develop?) an impact in the Pacific Ocean?
As to the mountains surrounding the Pacific Ocean, and your proposed impact
crater, would you please do the following for us:
1) Describe, in detail, the tectonic, mineralogical, geochemical and
geophysical signatures that would be expected to be prevalent in those
surrounding mountain ranges if they were caused by an impact structure. Also
discuss the relative ages of those mountain ranges.
2) Please explain, in detail, why those tectonic, mineralogical, geochemical
and geophysical signatures that would be prevalent in mountain ranges
caused by an impact structure are ubiquitously absent in said mountain
ranges. Please explain the dichotomy of the relative ages of those mountain
ranges when compared to a proposed impact site.
3) Please explain why you believe, and what proof you have, that the
world-wide geologic and geophysical communities have done their job so
poorly that all members have missed [sic] all of the tectonic,
mineralogical, geochemical and geophysical signatures that would be
ubiquitously present in said mountain ranges, if they were due to an impact
structure.
--
DQ
Alan Johnson
Sounds like homework to me:-)
Regards
--
Alan Johnson, Staatlich Geprüfter Geologietechniker
Geological and geotechnical translations, German>English
Abusus non tollit usum
http://home.t-online.de/home/ajohnson/pages/intro.htm
alin...@my-deja.com
No. The other way around. I proposed that the impact only created
Pangaea, and the mountains around the Pacific Ocean. The time for the
impact could be other that 280 Ma. Maybe as far back as 800 Ma. Plate
tectonics could still be the right answer to what happened after that.
>
> As to the mountains surrounding the Pacific Ocean, and your proposed
impact
> crater, would you please do the following for us:
>
> 1) Describe, in detail, the tectonic, mineralogical, geochemical and
> geophysical signatures that would be expected to be prevalent in those
> surrounding mountain ranges if they were caused by an impact
structure. Also
> discuss the relative ages of those mountain ranges.
>
> 2) Please explain, in detail, why those tectonic, mineralogical,
geochemical
> and geophysical signatures that would be prevalent in mountain ranges
> caused by an impact structure are ubiquitously absent in said mountain
> ranges. Please explain the dichotomy of the relative ages of those
mountain
> ranges when compared to a proposed impact site.
>
> 3) Please explain why you believe, and what proof you have, that the
> world-wide geologic and geophysical communities have done their job so
> poorly that all members have missed [sic] all of the tectonic,
> mineralogical, geochemical and geophysical signatures that would be
> ubiquitously present in said mountain ranges, if they were due to an
impact
> structure.
>
> --
> DQ
>
I suggested that the mountains could have been created by an impact.
But that is only _my_ opinion. I posted the theory hoping for answers
about questions like this from you experts. And for the geophysical
signatures, I am sure that the geophysical communities not have missed
any signature. The plate tectonic forces could have worked on these
mountains for a very long time after the impact so that older
signatures no longer are visible.
/Anders
Don Quixote
<alin...@my-deja.com> wrote in message news:8tn26b$461$1...@nnrp1.deja.com...
(snip)
> >
> > >The new theory does not necessarily contradict plate tectonics. It
> > > could very well be a development of PT.
> >
> > How did PT cause [sic] (develop?) an impact in the Pacific Ocean?
>
> No. The other way around. I proposed that the impact only created
> Pangaea, and the mountains around the Pacific Ocean. The time for the
> impact could be other that 280 Ma. Maybe as far back as 800 Ma. Plate
> tectonics could still be the right answer to what happened after that.
I was only reading it as you wrote it. Thusly:
"It (*the new theory*... as the *subject* from the first sentence)) could
very well be a development OF (my emphasis) PT."
How else do you read those two sentences?
(snip)
> I suggested that the mountains could have been created by an impact.
> But that is only _my_ opinion. I posted the theory hoping for answers
> about questions like this from you experts. And for the geophysical
> signatures, I am sure that the geophysical communities not have missed
> any signature. The plate tectonic forces could have worked on these
> mountains for a very long time after the impact so that older
> signatures no longer are visible.
Your assumption that PT would have destroyed certain signatures of a massive
impact structure in the surrounding mountain ranges is incorrect. You really
do need to study PT and understand it. It is wrong for you to propose a new
theory, and then expect us to do your homework for you.
Answer the questions that I presented in the prior post. Do not assume that
all evidence will have been destroyed by later PT, because that is an easily
disproved assumption, IF you understand subduction and volcanism, AND the
geology of all of the mountain ranges that you are throwing into your
theory.
If you cannot answer the posited questions then you do not understand any of
the evidence that is necessary to prove your theory, and necessary to
fasify PT that shows activity at least as early as the late Archean, if not
earlier.
The ball is in your court... after all, it is YOUR new theory.
--
DQ
alin...@my-deja.com
alin...@my-deja.com
$1...@nnrp1.deja.com...
>
> (snip)
> > >
> > > >The new theory does not necessarily contradict plate tectonics.
It
> > > > could very well be a development of PT.
> > >
> > > How did PT cause [sic] (develop?) an impact in the Pacific Ocean?
> >
> > No. The other way around. I proposed that the impact only created
> > Pangaea, and the mountains around the Pacific Ocean. The time for
the
> > impact could be other that 280 Ma. Maybe as far back as 800 Ma.
Plate
> > tectonics could still be the right answer to what happened after
that.
>
> I was only reading it as you wrote it. Thusly:
>
> "It (*the new theory*... as the *subject* from the first sentence))
could
> very well be a development OF (my emphasis) PT."
>
> How else do you read those two sentences?
Sorry, my mistake. What I meant was that the new theory could
complement PT.
The mountains around the Pacific Ocean not created by volcanism has
been created by subduction - a huge force deforming erosion-exposed
continental crust by aeons of time. How easy can it be to find any
original signatures after such massive process.
ara...@my-deja.com
alin...@my-deja.com wrote:
> I am not saying that the plate tectonics theory is wrong. But maybe
> some mountains came from an impact. Other mountains could be the
> results of plate tectonic processes. Apart from volcanoes, what kind
of
> mountains surrounds the Pacific Ocean?
>
> /Anders
Thrust and fold belts are more common than volcanic accumulations. Also
note that a mountain is only a relative altitude difference and is
related to the rate of eroion being less than the rate of uplift.
alin...@my-deja.com
ara...@my-deja.com wrote:
> In article <8tlo1p$1mt$1...@nnrp1.deja.com>,
> alin...@my-deja.com wrote:
> > I am not saying that the plate tectonics theory is wrong. But maybe
> > some mountains came from an impact. Other mountains could be the
> > results of plate tectonic processes. Apart from volcanoes, what kind
> of
> > mountains surrounds the Pacific Ocean?
> >
> > /Anders
>
> Thrust and fold belts are more common than volcanic accumulations.
Also
> note that a mountain is only a relative altitude difference and is
> related to the rate of eroion being less than the rate of uplift.
>
My theory is that subduction and erosion has added to these mountains
so that the only proof of the original mountains is their present large
sizes.
Could this be true?
/Anders
Don Quixote
<alin...@my-deja.com> wrote in message news:8tng56$hb4$1...@nnrp1.deja.com...
(snip)
>
> The mountains around the Pacific Ocean not created by volcanism has
> been created by subduction -
What process would you say causes the volcanism around the rim of the
Pacific Ocean?
>a huge force deforming erosion-exposed
> continental crust by aeons of time. How easy can it be to find any
> original signatures after such massive process.
Have you done any field mapping and sampling in any of the mountain ranges
surrounding the Pacific Ocean?
--
DQ
alin...@my-deja.com
"Don Quixote" <donqu...@windmills.com> wrote:
>
> <alin...@my-deja.com> wrote in message news:8tng56$hb4
$1...@nnrp1.deja.com...
>
> (snip)
>
> >
> > The mountains around the Pacific Ocean not created by volcanism has
> > been created by subduction -
>
> What process would you say causes the volcanism around the rim of the
> Pacific Ocean?
>
A rift breaking up? The point is, volcanic rock can hide signatures as
can rock created by subduction alone.
> >a huge force deforming erosion-exposed
> > continental crust by aeons of time. How easy can it be to find any
> > original signatures after such massive process.
>
> Have you done any field mapping and sampling in any of the mountain
ranges
> surrounding the Pacific Ocean?
No
>
> --
> DQ
Don Quixote
<alin...@my-deja.com> wrote in message news:8tnp73$ot4$1...@nnrp1.deja.com...
> In article <j0IL5.1555$fP1...@newsfeed.slurp.net>,
> "Don Quixote" <donqu...@windmills.com> wrote:
> >
> > <alin...@my-deja.com> wrote in message news:8tng56$hb4
> $1...@nnrp1.deja.com...
> >
> > (snip)
> >
> > >
> > > The mountains around the Pacific Ocean not created by volcanism has
> > > been created by subduction -
> >
> > What process would you say causes the volcanism around the rim of the
> > Pacific Ocean?
> >
>
> A rift breaking up? The point is, volcanic rock can hide signatures as
> can rock created by subduction alone.
You stepped into a deep hole on this one... sorry. The volcanic mountains
around the Pacific Rim are nearly all caused by subduction. You basically
cannot have *volcanic mountains* AND *subduction mountains* as two seperate
categories; they are one-in-the-same. (This , of course, does not include
the mid-plate, hot-spot volcanic mountains). Mountains caused at
*non-subduction* collisional boundaries are a seperate matter.
>
> > >a huge force deforming erosion-exposed
> > > continental crust by aeons of time. How easy can it be to find any
> > > original signatures after such massive process.
> >
> > Have you done any field mapping and sampling in any of the mountain
> ranges
> > surrounding the Pacific Ocean?
>
> No
If you had you would know that a great amount of the geologic column is
fairly well preserved (albiet folded, faulted, mashed and intruded) and any
*impact* signatures from an event of the size you propose would be readily
evident.
--
DQ
ara...@my-deja.com
I do not see how erosion can add to the "present large size" of a
mountain. Subduction indirectly leads to volcanism in some places that
can result in the formation of volcanic cones.
alin...@my-deja.com
No, I meant that the subduction/volcanism together with erosion had
hidden the original mountains.
alin...@my-deja.com
"Don Quixote" <donqu...@windmills.com> wrote:
>
> <alin...@my-deja.com> wrote in message news:8tnp73$ot4
I was trying to tell you that the mechanisms behind the creation of
these mountain was beside the point. This is why a said by subduction
ALONE.
> >
> > > >a huge force deforming erosion-exposed
> > > > continental crust by aeons of time. How easy can it be to find
any
> > > > original signatures after such massive process.
> > >
> > > Have you done any field mapping and sampling in any of the
mountain
> > ranges
> > > surrounding the Pacific Ocean?
> >
> > No
>
> If you had you would know that a great amount of the geologic column
is
> fairly well preserved (albiet folded, faulted, mashed and intruded)
and any
> *impact* signatures from an event of the size you propose would be
readily
> evident.
This, on the other hand, of course indicates a serious flaw in the new
theory.
Christine Wells
<alin...@my-deja.com> wrote in message news:8todj1$8fh$1...@nnrp1.deja.com...
If there had been erosion of an earlier set of mountains then there would be
one heck of a sedimentary signature akin to the old red sandstone from the
erosion of the caledonian mountains after subduction. I don't believe there
is evidence of such sedminentation here.
Chris.
BeamMeUp60
Mitchell Isaacs
> In article <j0IL5.1555$fP1...@newsfeed.slurp.net>,
> "Don Quixote" <donqu...@windmills.com> wrote:
> >
> > <alin...@my-deja.com> wrote in message news:8tng56$hb4
> $1...@nnrp1.deja.com...
> >
> > (snip)
> >
> > >
> > > The mountains around the Pacific Ocean not created by volcanism has
> > > been created by subduction -
> >
> > What process would you say causes the volcanism around the rim of the
> > Pacific Ocean?
> >
>
> A rift breaking up? The point is, volcanic rock can hide signatures as
> can rock created by subduction alone.
the type of volcanism - acidic, basic, volatile content, silica etc etc.
Then we can look at isotopic ratios. You can often tell where abouts the
various minerals have come from due to various isotopic ratios, and also
looking at various accessory minerals (I don't know much about this - I have
only quickly glanced at various articles. Don't have any refs, sorry -
geological journals, and ones such as science, nature will have articles &
letters though)
Seismic imaging can often tell us a bit as well.
So we can often tell where a lot of the magma came from by looking at the
various bits of information to hand. (again, don't have any specific
data/refs to hand)
Cheers,
Mitchell