David,
     I pointed out that salt intrusions are all metamorphic, and that  
sandstone dikes are neither sandstone or a dike when or after they  
formed until subsequent events occur.
cheers,
eric


On Nov 26, 2009, at 5:11 AM, Macdonald, Professor David I. M. wrote:

> 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..
>
>