Re: Volcanic cooling - Physics anyone?

Glenn Morton (
Tue, 11 Mar 1997 20:38:58 -0600

At 01:55 PM 3/11/97 GMT, David J. Tyler wrote:
>This post provides feedback to Glenn Morton (6 March), Steve
>Smith (6 March) and Glenn Morton (9 March). The exchange on
>cooling of large magma bodies continues ...
>On Thu, 06 Mar, Glenn Morton wrote:
>>I think your argument is viewing the intrusion of a
>>magma as a closed system - whereas I would want to explore the
>>thought that the system is open and there are many inter-related
>>and interdependent disturbances.
>"I am aware of this non-magmatic tectonism but that is irrelevant
>to the problem of cooling a batholith because we find batholiths
>in tectonically inactive areas like the East Coast of the United
>I would hesitate to describe ANY area as "tectonically inactive":
>everything is relative. Within a Plate Tectonics framework, you
>OUGHT to have plenty of tectonic activity wherever you have
>batholiths emplaced.

I wouldn't hesitate to describe the East Coast of the US as tectonically
inactive. I spent 3 years studying and working the East Coast. I agree with
you about what OUGHT to be, namely that there should be lots of tectonic
features. But I never did understand the East Coast because all faulting
stopped in the Triassic. Hardly a fault extended into the jurassic except at
the present day shelf edge. As I have mentioned before, the near total lack
of Mesozoic faulting (faults almost always occur during tectonism) made this
area a terrible oil province (and a very frustrating one for those like me
who wanted to find oil) I would suggest that you look in the Library at
A.W. Bally, "Seismic Expression of Structural Styles", Vol. 1, AAPG, 1983,
p. 1.3-4. This shows a seismic line which goes across the intrusive known
as the Great Stone Dome. The coordinates for this feature are approx. 39 deg
30 min north, 73 deg W 30 min.. When this feature was emplaced it caused a
local uplift as the magma displaced the Jurassic rocks. There was lots of
erosion on top of the dome after it was emplaced, as about 7,000 feet of
Jurassic rock was eroded off. Then lower Cretaceous strata to holocene
sediments were placed on top of the erosional surface. There is no faulting
visible on the seismic lines either before or after this erosional interval
which represents the emplacement of the magma.

>GM: "The Great Stone Dome that I mentioned a while back as well
>as diabase sills found on Georges Bank offshore Massachusetts,
>are in areas that did not suffer from much regional tectonism.
>The entire problem with the oil potential of the east coast was
>that there was too little faulting, which means too little
>tectonism, yet there are still some batholiths."
>Maybe this is a sign that conventional models are inadequate to
>explain the observations ... IF they did not form in the
>"normal" way, I would be very cautious about an argument that
>assumed they did.

But of course you can't use this to conclude neocatastrophism or any other
model, since the other models can't explain it either.

>>Again, you appear to regard the system as closed: an assumption
>>I would not wish to defend. The analogy of pillow lavas is a
>>good one as far as the chilling of the magma is concerned, but
>>pillow lavas also illustrate aspects of open systems: as the
>>magma moves inside the pillows, the "rind" may swell and
>>fracture, or may collapse and implode.
>GM: "But at the point that the magma chamber ceases motion, the
>rind can no longer swell. If the magma chamber never went
>through this phase, there would be no cool batholiths. At some
>point the rind must never again swell and break. this is the
>point at which the long cooling time begins to happen.
>Whilst I am tempted to agree with you, I am actually going to
>disagree - to make a point. I am arguing that closed systems
>cannot be assumed, and that there is plenty of field evidence to
>support the idea of openness. Do you not have faulted granite
>plutons like us in the UK? Even when solid, fracturing can
>continue, opening up new channels. Solid granites have no
>shortage of channels for water movement. One of the reasons the
>Hot Dry Rock project failed (in Cornwall, UK) is that the
>injected water leaked away too quickly, and the research team
>could not confine the steam. There were just too many routes for
>water to escape.

Yes, there are some wonderful granites just north of here about 200 miles
and they are faulted. But my understanding of the faulting is that it does
not seem to be associated with coolong but post emplacement tectonism. But
I haven't studied those granites in any detail and may be wrong. These are
at the eastern end of the Arbuckle mountains which is a very deformed area.


>On Sun, 09 Mar 1997, Glenn Morton wrote:
>"Hi David, I got several of the articles that you suggested.
>I have learned a couple of things. First an active hydrothermal
>system which is removing heat from a batholith also removes
>oxygen-18 from the rocks below...."
>This is true. Isotopic fractionation mechanisms are linked, for
>example, to chemical reactions, boiling, and filtration through
>GM: "Intrusions which did not undergo a hydrothermal cooling are
>also found. They have a normal isotopic signature because the
>O-18 couldn't escape. one such conductively cooled intrusion is
>the Santa Rosa intrusion."
>This does seem significant. I would be happier if this were one
>of several complementary lines of evidence, all pointing in the
>same direction. The details of the Santa Rosa pluton warrant
>closer examination, but for the present, in this case, I accept
>that the evidences for convection are lacking.

I no longer know where you stand on the age of the earth and you may not
want to discuss that here (and I don't recall you being a young earther
anyway), but if convection is present, Steve presented good evidence that it
still would take 100,000 years for one of thes intrusions to cool. without
it, the time frame could be much longer. For the young earth creationists
this is quite a problem.

>GM: "This is an 8 x 16 km wide intrusion so conductive cooling
>would take a long long time.
>While I know that you, David, have stated that you don't need to
>have all the intrusions cooled within a year, there are those on
>the list who need to have everything cool within a 4-6000 year
>period. Intrusions lacking hydrothermal activity present a
>greater problem for their chronology since these things remain
>hot for hundreds of thousands of years."
>The "convective cooling" scenario was not presented (in my posts)
>as a panacea to permit short timescales, but where it is
>applicable, it can dramatically shorten timescales. I would not
>want to claim it is always applicable: if geology is to be a
>science, theory must be sensitive to the data. This is,
>ultimately, my reason for challenging the "conduction-cooling"
>model. It is also my justification for being interested in some
>of the other "unorthodox" theories mentioned earlier in this
>thread. I have come to the conclusion that there is far more
>catastrophism in the geologic record than can be accommodated by
>the current "orthodoxy" - despite its protestations that it can
>accommodate catastrophes. When you get down to the
>interpretation of field evidences, the legacy of Lyell is still
>very strong. There is a real need to identify more clearly the
>assumptions in models; to develop ways of testing those
>assumptions; and to be more alert to alternative paradigms of

I would like to object to one thing which you said.

>When you get down to the
>interpretation of field evidences, the legacy of Lyell is still
>very strong.

David, this is not directed at you but at any potential listeners. It is an
editorial comment. Christians often use this type of statement to avoid
difficult conclusions. By making science an "interpretation" only, kind of
like an interpretation of the Bible", we make an equivocation that I do not
feel is justified. An example,

"This conclusion was still further confirmed in the
after-effects of the 1980 volcanic explosion at Mount St. Helens .
. . . Up to 600 feet of laminated sediments were deposited in a
single day, looking exactly like stratified beds normally
interpreted to represent long ages."~ Henry M. Morris and John D.
Morris, Science, Scripture, and the Young Earth, (El Cajon:
Institute for Creation Research, 1989), P. 35.

An equivocation like this makes it sound like the Mt. St, Helen's beds are
made up of various lithologies (like sandstone, limestone and shale) instead
of the single lithology (volcanic ash) which is the actual case. It makes
it sound like the mt. St. Helens beds have footprints, burrows etc like all
those beds that geologists think took a long time. There are none of these
features in the middle of theMt. St. Helens beds. Christians too often
equivocate with this "interpretation" business and fool those who don't know


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