For those of you who may have missed these things have a look at:
http://pgc.lyellcollection.org/content/6/133.abstractMore if you google "clastic injectites" which will give you some insight
into how big and potentially interesting these things are.
Injectite or intrusion folks?
alan
-----Original Message-----
From: Tectonics & structural geology discussion list
[mailto:[log in to unmask]] On Behalf Of Jackson, Christopher A -
L
Sent: 26 November 2009 15:14
To:
[log in to unmask]Subject: Re: Anderson Stress Meeting: September 2010 reminder
Hi All,
Seems like we are straying into a discussion about 'forcibly-intruded'
clastic dykes (typically injected upwards) vs. 'passively-emplaced' clastic
dykes which fill in long-lived, open fractures (i.e. ones forming in
metamorphic basement as Bob describes below). This is OK, as long as we are
al clear on what we are talking about.
Chris
P.S. Bob: I'll have one of the JSG pre-prints if you don't mind!
---------------------------------------------------------------
Dr Christopher A-L Jackson
Statoil Senior Lecturer in Basin Analysis Department of Earth Science &
Engineering Imperial College Prince Consort Road London
SW7 2BP
ENGLAND
email:
[log in to unmask]web: www.imperial.ac.uk/people/c.jackson
phone: +44(0)2075947450
-----Original Message-----
From: Tectonics & structural geology discussion list
[mailto:[log in to unmask]] On Behalf Of HOLDSWORTH R.E.
Sent: 26 November 2009 14:35
To:
[log in to unmask]Subject: Re: Anderson Stress Meeting: September 2010 reminder
Christine and all,
We here at Durham have had some interest in clastic infills in crystalline
rocks - including ones that have been injected. For example, try Beacom et
al. 1999 for examples within the Lewisian Gneisses:
Beacom, L.E., Anderson, T.B. & Holdsworth, R.E. 1999. Using basement hosted
clastic dykes as syn-rifting palaeostress indicators: an example from the
basal Stoer Group, Scotland. Geol. Mag. 136, 301-310.
I'll send you - and anyone else who want one - a reprint separately.
More recently, Rich Walker who has just submitted his PhD here has found
similar features in Tertiary basalts in the Faroe Islands and is about to
start a post doc studying equivalent features for a further 2.5 years funded
by a major oil company (contract pending, so i'll refrain from naming
names). If you want I can send a pre-print of a paper we are about to submit
to JSG on these, though they are mostly sediment fills with only minor
injectites. He will be presenting some of his work as a poster at AGU if you
want to come and find him or me.
Finally, we also have two PhD students funded by a consortium of companies
associated with the Clair field, west of Shetland who are studying fracture
systems in the crystalline basement of the Lewisian Complex of NW Scotland
(Jen Martin, Ben Franklin). Many of these fracture systems are associated
with clastic fills and/or injectites.
Jen will also be presenting some of her work as a poster at AGU. The
companies are interested in this work as a substantial volume of oil is
hosted in fractured basement in the Clair Field.
Fianlly, you might also want to seek out these possibly related papers:
Richter, D. 1966. On the New Red Sandstone Neptunian Dykes of the Tor Bay
Area (Devonshire). Proceedings of the Geological Association, 77,
173-186
Wright, V., Woodcock, N.H., Dickson, J.A.D. 2009. Fissure fills along
faults: Variscan examples from Gower, South Wales. Geological Magazine,
Cambridge
Best wishes
Best wishes
Bob Holdsworth
Prof Bob Holdsworth,
NERC KE Fellow,
Reactivation Research Group,
Dept of Earth Sciences,
University of Durham,
Durham DH1 3LE,
UK
Tel +44(0)1913342299
Fax +44(0)1913342301
e-mail (including jsg business):
[log in to unmask]Web:
Dept: http://www.dur.ac.uk/earth.sciences
RRG - http://www.dur.ac.uk/react.res/RRG_web
Geospatial Research Ltd (GRL) - www.geospatial-research.com
-----Original Message-----
From: Tectonics & structural geology discussion list
[mailto:[log in to unmask]] On Behalf Of Christine Siddoway
Sent: 26 November 2009 13:39
To:
[log in to unmask]Subject: Re: Anderson Stress Meeting: September 2010 reminder
Importance: High
Greetings, Carl and others,
AMS on sandstone intrusions: Mike Petronis and I have an investigation
underway of sandstone dikes within crystalline rock in the Front Range of
Colorado. Our recent abstract with initial results is at:
http://aapg09.mapyourshow.com/2_1/sessions/session.cfm?ScheduledSessionI
D=15
32. The scale of the intrusions, incidentally, is 5 cm to >7 meters, with
many exceeding 2 m in width.
I'd like to now ask, can any list members tell me of other examples of
clastic dikes within a crystalline host? My web searches yield little!
Regards,
Christine Siddoway
On 11/26/09 4:24 AM, "Carl Stevenson" <
[log in to unmask]> 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.