I have to say that I was using the first thing that popped into my head as an example, and having heard basalts sometimes described as either mafic or ultramafic, I reckoned it would do, but I nearly wrote "green notebooks"; perhaps I should have.
As a seismologist, I wouldn't know a komatiite from a kontikiite.
Roger
> -----Original Message-----
> From: Tectonics & structural geology discussion list [mailto:GEO-
> [log in to unmask]] On Behalf Of Eric Essene
> Sent: 27 November 2009 16:12
> To: [log in to unmask]
> Subject: last comment
>
> Roger and all,
> The term ultramafic basalt is simply a tautology because a basalt
> is mafic but not ultramafic. Who uses that term, anyway? I commonly
> seen komatiitic basalt or basaltic komatiite, which is unfortunate
> because komatiite is an ultramafic rock with a certain texture.
> Sometimes such terms are invented because the rock is close to a
> boundary with another name as if that in any way is surprising.
> Basaltic andesite has since grown over time to have its own field. If
> the komatiitic basalt has a komatiitic texture, that is logical, a
> basalt with komatiitic texture as opposed to one that has none. It
> remains confusing chemically. Igneous basalt is ridiculous because it
> is redundant, the first term in no way further constraining the second.
> An olivine gabbro is not ultramafic unless it is a lherzolite. The
> proper use of preceding adjectives and nouns in compound nouns is that
> they must further constrain the final noun, which is also your opinion
> I see.
> Moreover, no more than a total of three adjectives, adverbs or
> nouns should be used in a chain; otherwise it leads to great
> uncertainty as to what is modifying what. I call the current fad of 4-
> 6 such modifiers Bushtalk for two of our most favorite recent
> presidents. One could say magnesian basalt or olivine basalt, but not
> ultramafic basalt or the redundancy mafic basalt, which in no way
> provides restricting information as you point out. Next will we have
> mafic igneous plagioclase pyroxene basalt? Scientists should use
> adjectives and adverbs sparsely and choose them well, like Hemingway,
> not blather on and on like George Elliot.
> cheers,
> eric
>
>
> On Nov 27, 2009, at 8:44 AM, Musson, Roger M W wrote:
>
>
> One could argue that adjectives play two roles in English. One is
> to distinguish nouns subject to the qualifying adjective from those not
> so qualified. Thus, "ultramafic basalts" are distinguished from other
> basalts that are not ultramafic. Under this interpretation, it would be
> absurd to write "igneous basalts", since there are no non-igneous
> basalts. However, it is quite common to find adjectives used merely as
> a way of expressing additional information about the noun. Thus, one
> could easily find someone writing "igneous basalts" to mean "basalts,
> which are igneous".
>
> Personally, I don't like it, and I prefer to strike out any
> adjectives that are not essential. Don't get me started on "organic
> vegetables".
>
> Roger Musson
>
>
>
>
> -----Original Message-----
>
>
> From: Tectonics & structural geology discussion list
> [mailto:GEO-
>
>
> [log in to unmask]] On Behalf Of Eric Essene
>
>
> Sent: 26 November 2009 18:51
>
>
> To: [log in to unmask]
>
>
> Subject: last comment
>
>
>
> Tim and all,
>
>
> This is my last online response on this topic.
>
>
> Maybe 'igneous intrusion' is used much more in the UK
> than here.
>
>
> If the terms 'sedimentary intrusion' and 'metamorphic
> intrusion' are
>
>
> seldom used, why is the construct necessary? Next will we
> use
>
>
> "sedimentary granite" or "sedimentary limestone"?
>
>
> A problem can arise if we don't agree on the meaning of
> the words.
>
>
> Yes, indeed, I did not understand the meaning of this
> particular
>
>
> notice that was just sent out by Rob and Zoe. Maybe some
> other notice
>
>
> was sent previously that was clearer.
>
>
> cheers,
>
>
> eric
>
>
>
>
> On Nov 26, 2009, at 11:26 AM, Tim Needham wrote:
>
>
>
> I'm not really sure why I'm replying to this but...
>
>
> Dare we consider that, unthinkably, Georef isn't
> quite up to speed
>
>
> on this?
>
>
> The 'keyword' approach is often frustrating and not
> very helpful. I
>
>
> suspect
>
>
> that most geoscientists worth their salt(!) know what
> an 'igneous
>
>
> intrusion'
>
>
> or 'clastic intrusion' is. The main benefit of this
> thread has been
>
>
> some of
>
>
> the highly informative references on clastic
> intrusions (thanks in
>
>
> particular to David Macdonald, Mads Huuse and Bob
> Holdsworth).
>
>
> Basically, we
>
>
> describe what we observe and go from there rather
> than try to
>
>
> pigeonhole
>
>
> into 'popular' terminology. Did anyone really
> misunderstand the
>
>
> actual
>
>
> conference announcement?
>
>
> Cheers
>
>
>
> Tim
>
>
>
> -----Original Message-----
>
>
> From: Tectonics & structural geology discussion list
>
>
> [mailto:[log in to unmask]] On Behalf Of
> Eric Essene
>
>
> Sent: 26 November 2009 15:48
>
>
> To: [log in to unmask]
>
>
> Subject: Re: Anderson Stress Meeting: September 2010
> reminder
>
>
>
> Carl,
>
>
> The term "sedimentary intrusion" has one citation
> in Georef.
>
>
> cheers,
>
>
> eric
>
>
>
> On Nov 26, 2009, at 6:24 AM, Carl Stevenson wrote:
>
>
>
> Hi all,
>
>
>
> Sedimentary intrusions - does anyone know of
> any AMS (anisotropy of
>
>
> magnetic susceptibility) work on these?
>
>
>
> Desperately resisting getting drawn in to a
> semantic debate, I think
>
>
> 'igneous intrusion' is fine. I guess it is as
> opposed to igneous
>
>
> extrusion - lavas and ash etc. Sometimes in
> when subvolcanic roots
>
>
> are exposed it is actually equivocal. There are
> instances when ash
>
>
> can fall back into a vent.
>
>
>
> An example I am aware of is:
>
>
> ALMOND, D. C. 1977. Sabaloka Igneous Complex,
> Sudan. Philosophical
>
>
> Transactions of the Royal Society of London
> Series a - Mathematical
>
>
> Physical and Engineering Sciences, 287, 595-
> 633.
>
>
>
> Cheers
>
>
> Carl
>
>
>
> -----Original Message-----
>
>
> From: Tectonics & structural geology discussion
> list
>
>
> [mailto:[log in to unmask]
>
>
> ] On Behalf Of Stu Clarke
>
>
> Sent: 26 November 2009 10:23
>
>
> To: [log in to unmask]
>
>
> Subject: Re: Anderson Stress Meeting: September
> 2010 reminder
>
>
>
> Don't you hate it when someone gets that email
> in just before
>
>
> you......
>
>
>
> I too have no particular stand on terminology,
> but I too was
>
>
> surprised by
>
>
> the stated scale of sedimentary intrusions. I
> have examined large
>
>
> scale
>
>
> sedimentary intrusions in deltaic settings and
> currently work with
>
>
> colleagues using oil-industry datasets on the
> same thing. I don't
>
>
> think
>
>
> sedimentary intrusions have to be small
> scale......
>
>
>
> Stu
>
>
>
>
> -----Original Message-----
>
>
> From: Tectonics & structural geology discussion
> list
>
>
> [mailto:[log in to unmask]] On Behalf
> Of Macdonald,
>
>
> Professor
>
>
> David I. M.
>
>
> Sent: 26 November 2009 10:11
>
>
> To: [log in to unmask]
>
>
> Subject: Re: Anderson Stress Meeting: September
> 2010 reminder
>
>
>
> Dear Eric
>
>
> I have no particular stand on the terminology
> for igneous rocks, but
>
>
> you are
>
>
> incorrect in your assertions on the scale of
> sedimentary
>
>
> intrusions. Salt
>
>
> is a sedimentary rock which can be injected
> through kilometers of
>
>
> strata in
>
>
> bodies hundreds of metres to kilometers across.
> Anyone who has ever
>
>
> worked
>
>
> on deltas can point to mud diapirism on a
> similar scale. Even the
>
>
> humble
>
>
> sand injection feature is much larger than you
> make out; your
>
>
> description
>
>
> seems to be of sand filling pre-existing
> cracks, whereas most sand
>
>
> injections are of a fluid slurry under
> pressure. These intrusions
>
>
> can be
>
>
> huge. In the Mesozoic forearc basin of the
> Antarctic Peninsula,
>
>
> sandstone
>
>
> dykes have been mapped with MINIMUM dimensions:
> 6 km long, cutting
>
>
> 350 m of
>
>
> strata, and 1 m wide. For more examples, see,
> among other papers:
>
>
>
> Hurst A. & Cartwright J. A. Eds. 2007. Sand
> Injectites:
>
>
> Implications for
>
>
> hydrocarbon exploration and production. Memoir
> 87 American
>
>
> Association of
>
>
> Petroleum Geologists
>
>
>
> Hurst A., Cartwright J. & Duranti D. 2003.
> Fluidization
>
>
> structures in
>
>
> produced by upward injection of sand through a
> sealing lithology.
>
>
> In:
>
>
> Subsurface sediment mobilization (eds. Van
> Rensbergen P.,Hillis
>
>
> R.,Maltman
>
>
> A. J. & Morley,C.K.), Geological Society Of
> London, London, 123-127
>
>
>
> Jonk R., Hurst A., Duranti D., Mazzini A.,
> Fallick A. E. & Parnell
>
>
> J.
>
>
> 2005.The origin and timing of sand injection,
> petroleum migration
>
>
> and
>
>
> diagenesis: the Tertiary petroleum system of
> the South Viking
>
>
> Graben, North
>
>
> Sea. AAPG Bulletin, 89, 329-357
>
>
>
> Hurst A. & Duranti D. 2004. Fluidisation and
> injection in the deep-
>
>
> water
>
>
> sandstones of the Eocene Alba Formation (UK
> North Sea).
>
>
> Sedimentology, 51,
>
>
> 3, 503-529
>
>
>
> Hope this helps
>
>
> David Macdonald
>
>
>
> -----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..
>
>
>
>
>
>
> The University of Aberdeen is a charity
> registered in Scotland, No
>
>
> SC013683..
>
>
>
>
>
>
>
> --
> This message (and any attachments) is for the recipient only.
> NERC
> is subject to the Freedom of Information Act 2000 and the
> contents
> of this email and any reply you make may be disclosed by NERC
> unless
> it is exempt from release under the Act. Any material supplied to
> NERC may be stored in an electronic records management system.
>
>
>
>
--
This message (and any attachments) is for the recipient only. NERC
is subject to the Freedom of Information Act 2000 and the contents
of this email and any reply you make may be disclosed by NERC unless
it is exempt from release under the Act. Any material supplied to
NERC may be stored in an electronic records management system.
|