Alan,
Of course your points are well taken if that is what the
conference is all about. Here are citations in Georef where the
compound phrase was put in quotes to be sure it was actually used:
"Igneous intrusion" 344
"metamorphic intrusion" 5
"sedimentary intrusion" 3
intrusion 23,247
we geologists have voted with their feet. That is the point of a
distinction without a difference. No one is using the terms that
everyone wants to carefully distinguish, so the whole concept has been
shrugged off in practice. Five of the papers in the conference can
make quite a difference if they are considered for citation in Georef,
actually doubling the cited usages that are currently there. These
are very important distinctions.
Next let's consider how the term plutonism means cold
precipitates in the ocean as it did 200 years ago?
eric
On Nov 26, 2009, at 4:53 AM, Alan Gibbs wrote:
> Hello,
>
> There is always the risk of sliding into pedantry; the terms "igneous
> intrusion", "sedimentary dyke" are well understood and I don't think
> really
> confuse or annoy anyone.
>
> What should be of common interest is how the space problem is
> resolved with
> respect to the stress conditions during intrusion of whatever the
> intruding
> material is (hot, cold, hot liquid, slurry etc.) and what the state
> of the
> country rock is (soft, hard, hot, cold etc.) at the time of
> intrusion. Those
> of us who have worked in both hard and soft rock areas have been
> struck by
> the similarities of intrusion style rather than by their undoubted
> differences.
>
> I hope that the conference can open up some discussion and debate on
> this
> and what it tells us about the natural system and avoid worrying too
> much
> about whether we think the other guy is using needless adjectives or
> sloppy
> terms like those in brackets above.
>
>
> alan
>
> -----Original Message-----
> From: Tectonics & structural geology discussion list
> [mailto:[log in to unmask]] On Behalf Of Eric Essene
> Sent: 26 November 2009 07:39
> To: [log in to unmask]
> Subject: Re: Anderson Stress Meeting: September 2010 reminder
>
> Rob,
> The term igneous intrusions is functionally a terrible term, a
> distinction without a difference. More than 99.9% (or more?) of the
> time it
> means igneous rocks where the term is redundant. If one talks about
> sedimentary intrusions it is on a meter scale feature, commonly even
> less--I
> have seen some down to cm scale. When they formed and well
> afterward they
> did not look like dikes, just fractures filled with loose sediment. I
> discount the poor term "sandstone dikes" as needing yet another
> confusing
> term.
> On the other hand salt domes are metamorphic (recrystallized)
> but not
> molten rock, well a little brine. They were not in the sedimentary
> group
> during formation. Yes, we have diapirs of metamorphic rock,
> although a lot
> of those gneiss domes probably have a little melt. I would agree
> about
> metamorphic diapirs but simply would not call them metamorphic
> intrusions to
> avoid confusion on a transitional rock. Gneiss domes are a nice
> description
> for them.
> It must be exceedingly rare for igneous petrologists/geochemists
> to be presenting data on "sand dikes". Salt domes are much larger
> but are as they form. Do you know of any igneous petrologist/
> geochemist who
> would report on them in your symposium? So "sandstone dikes" are
> fractures
> filled with loose clastic material and water, salt diapirs are all
> metamorphic and may have brine, gneiss domes are often partial melts
> then at
> least partly igneous, and the term "igneous intrusion" is clearly
> redundant
> to the average passerby. Is this really a useful terminology?
> cheers,
> eric
>
> On Nov 26, 2009, at 12:17 AM, Butler, Robert wrote:
>
>> Eric
>> Actually - there are lots of non-igenous intrusions in basins -
>> sandstone dykes through 100s metres of strata. Not to mention mud
>> diapirs, salt etc etc.... gas chimneys....
>> go google!
>> Cheers
>> Rob
>>
>> ________________________________________
>> From: Tectonics & structural geology discussion list
>> [[log in to unmask] ] On Behalf Of Eric Essene
>> [[log in to unmask]]
>> Sent: 26 November 2009 05:09
>> To: [log in to unmask]
>> Subject: Re: Anderson Stress Meeting: September 2010 reminder
>>
>> Rob, Zoe, and all,
>> Igneous intrusions as opposed to all those sedimentary plutons?
>> The phrase is nearly always meaningless and should not be used.
>> Sounds like a great trip.
>> cheers,
>> eric
>>
>>
>> On Nov 25, 2009, at 11:28 PM, Butler, Robert wrote:
>>
>>> Dear all
>>> As we get our diaries together for 2010 we thought it timely to
>>> remind you of the conference next year:
>>>
>>> Stress controls on faulting, fracturing and igneous intrusion in the
>>> Earth's crust
>>>
>>> A meeting to commemorate the work of Ernest Masson Anderson on the
>>> 50th anniversary of his death.
>>>
>>> 6-8 September 2010 at the University of Glasgow, UK
>>>
>>> Organisers: Zoe Shipton, Rick Sibson, Dave Healy, Rob Butler
>>>
>>> We will send out details of the meeting ("First Circular") in
>>> January
>>> - Abstract deadline will be end April with a preliminary programme
>>> drawn up through May.
>>> We are also planning a fieldtrip to the Hebrides and NW Scotland to
>>> examine a variety of faults and the Tertiary igneous complexes.
>>> Again - further information will be included in the first circular.
>>>
>>> Hope to see a bunch of you in Scotland next September!
>>> Zoe, Rick, Dave and Rob.
>>>
>>>
>>> The University of Aberdeen is a charity registered in Scotland, No
>>> SC013683..
>>>
>>>
>>
>>
>> The University of Aberdeen is a charity registered in Scotland, No
>> SC013683..
>>
>>
>
>
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