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OK - more to do. Need to separate the cold diapiric stuff from the hot diatremic stuff. Later - :-) Vsmith 12:53, 6 December 2005 (UTC)
Yeah, especially as diatremes are not diapirs. Rolinator 00:50, 22 December 2005 (UTC)
The original paper by Mrazec described diapirs from Roumania where salt cores have 'pierced across' and breached an overlying anticline. The folds are assymetric, compressive in style suggesting some 'tectonic energy' driving the intrusion. These pierced folds are very different to Gulf Coast salt domes.
Further, I don't believe that 'bouyancy' is essential for intrusion. The driving force for any intrusion is the weight of the adjacent overburden/cover which 'sinks' into the source layer, driven by gravity. The one factor that allows this release of gravitational energy is the MOBILITY of the intruding material. For example, sea water will rise up a hole/crack in an ice floe, forming an 'intrusion', yet the ice is less dense than the water otherwise the ice would sink. Even mercury will rise up a hole in a styrafoam block floating on it.
Sure, salt is less dense than typical host rocks/overburden, but its most important property, for intrusion, is its ability to flow(especially if wet and hot)in response to very low stresses. It is a time-dependant fluid, or 'rheid', rather like pitch/bitumen (and glass, marble etc). A tombstone (see old marble examples) or window (see glass in old cathedrals) of rock salt will droop and flow like treacle, given enough time
The lavalamp is a poor example of a 'diapir'.
A mobile intruding material that is LESS dense than the overburden simply has the potential to EXtrude (the cover sinks completely). If more dense, the intrusion will penetrate the cover to some point, then cease.
This is especially the case in extensive terrains where intrusion can be 'permitted' by tensional zones in the cover; even 'pull aparts' in compressive zones.
Forget about 'low density'; mobility is the key to intrusion.
Perhaps we should forget about 'diapirs' and just call them 'intrusions (salt, granite, shale, mud, breccia etc)'?
Cheers tmount 00:41, 27 February 2007 (UTC)
Appreciate comment on glass viscosity and withdraw reference to'cathedral windows' although input from a physicist on time-dependent fluids/viscosity or rheids would be useful. Salt is certainly a rheid, especially when wet/hot.
But it is my understanding that real-time measures of viscosity are meaningless in geological time frames . . . 'rheidity', or 'time-dependent viscosity' is the key, with flow of pitch being an example. Pure halite has 'no (measurable) ultimate shear strength', meaning it will flow, in time, in response to (any?) stress . . presumably a fly landing on it will eventually sink into the 'solid'. Even quicker for hot and wet salt. Expert input required here, and I am trying to recall research I did 38 years ago!
Tjmount (
talk)
20:27, 24 February 2009 (UTC)
Agree with most of your comments re layer instabilities etc, and the role of bouyancy in forming the classic US Gulf coast domes . . . and lava lamps.
However, my work was done in the Flinders Ranges of South Australia where the intruded host material was demonstrably unyielding and BRITTLE at salt emplacement (no Rayleigh-Taylor waves here), as evidenced by dyke wedging, roof grabens (extension normal to S1, bounding faults aligned parallel to S1=profile planes of anticlines), very sharp contacts with shape matching ('continental drift' style) across intrusions, stoped host blocks (to kilometres long = 'titaniclasts') etc. Instead of your 'holes' (above), I suggest the complex of intruding salt dykes were emplaced up S1/S2 structural planes, parallel to S1, normal to S3 principal stress directions, which at the regional scale was the direction of tectonic compression. Locally, the orientation of dyke planes varied with local stress field directions, giving complexity to the salt dyke swarms. In particular, smaller salt breccia dykes invade the two conjugate joint plane sets on the folds, as well as the usual axial and profile plane joints/faults. So where the overburden is thick, S2 is great and S3 becomes the direction of minimum stress . . . and even EXTENSION, as in the cores of massive Flinders Ranges regional anticlines.
Yes, I think you have got it . . . stuctural control, dykes into planes normal to S3=least or even tensional stress with extension as the dykes 'wedged' in as the fold grew under regional compression. Tjmount ( talk) 20:34, 24 February 2009 (UTC)
These are 'passive / permitted intrusions'
In a sence, the heavy fractured/blocky brittle overburden has foundered or sunk into the fluid salt layer, with the salt being further energised by lateral teconic/compressive forces.
I am trying to think of an example, but perhaps a glass of water filled mostly with crushed ice where the glass walls restrain lateral movement (ie 'tectonic forces') . . . the mobile (but, note, denser!)water rises and fills the voids between the clasts to a level way above 'isostatic' expectations.
Yes, I need help on this one and the glass model may not be the best. The point is, for a fractured brittle overburden, a mobile (but relatively dense, as for water up cracks in less dense/brittle ice breccia) material can move up a long way. Potentially to the surface where it 'extrudes' if it is less dense. How far vertically would a wet/hot (250deg C?)and mobile halite/anhydrite mush, with entrained dolostone/siliciclastic/dolerite clasts, intrude in a very thick (total to 40km) overburden of lithified rift sediments; as in the Flinders Ranges. First, on isostatic principles, then adding compressive energy? Think 'a salt -fluidised mush, based on a very poorly sorted 'fractal' breccia with clasts across a wide size range (dust to several km) such that the fines act as a mobile matrix (eg granular flow, like wheat) to larger clasts. Pore space could be as low as 10 to 15 % with the voids filled with 'fluid/plastic' salt which allows particle rotation and flow of the breccia. 'Salt rheidised/fluidised' in my terms. After emplacement, the mass cools, salt is leached out, and the intrusion becomes solid (with no obvious salt masses) in time, as in the Flinders Ranges. Zeolite facies cements (calcite, talc, silica, pure low-T adularia, magnesioriebeckite, dusty heamatite from dedolomitisation reactions during intrusion) etc lock up the breccias. Tjmount ( talk) 21:09, 24 February 2009 (UTC)
All this is very like Mrazec's Type 'diapirs' where salt has been injected across the cores of compressive folds.
There is a real need to rethink these mechanisms, towards the development of a 'grand unified theory if all intrusions' in which we can all insert our piece of the model.
Tjmount ( talk) 00:52, 23 February 2009 (UTC)
What my Flinders work showed was that all the traditional Gulf salt dome/lava lamp/Ramberg centrifuge thinking might not be the full story. In South Oz, at least, I became increasing nervous about geoworkers attributing every structural disruption, conglomerate, or facies change to the ubiquitous 'energetic punch up through the adjacent cover of a bouyancy driven low density salt 'diapir'.
Circular reasoning was common . . . 'here is a conglomerate . . . thus a diapir nearby . . . which must have shed conglomerates.
I quickly got a bad reputation by asking for proof that the conglometic clasts 'once were resident in a diapir'
Similarly, that latest trend is to attribute local facies changes in 'mini basins' to 'salt withdrawal and diapir emplacement' but this is not proof, especially where an active block faulted basement underlay the rift.
I could only see gentle, synteconic, passive emplacement of breccias of low salt content/low or higher density . . as above.
'Bouyancy' is something I have never really understood, like 'aerodynamic lift' over a wing. Seems we should get back to physical first principles (eg thermodynamics) and abandon comfortable assumptions.
It seems reasonable that all intrusions (diapirs, batholiths, salt domes, diatremes, igneous stocks, mid-oceanic dykes, lava lamps, mud up between the toes, sauces in puddings, C/Nimbus thunderheads/thermals, mantle plumes,) must all be driven by a single common set of simple principles (GUT of Intrusions). Glaciers and rivers probably follow the same rules, but upside down, air is the host, and more horizontal than vertical!
My challenge is to ask if the potential energy of a system can be lowered in a gravitational field by the migration of matter where mobility of the invading material is the key, subordinate to the effects of relative densities. Tjmount ( talk) 21:57, 24 February 2009 (UTC)
Importantly, the Wiki aim must be to provide good reliable information to a range of users, including those not so interested in acaddemic discussions.
So . . .
can we now EDIT the Wiki 'diapir' definition page to give an extended definition of intrusions (using modern concepts, based on your words, above) and show where 'diapirs' fit into the suite (and refer to Mrazec).
Begin with an introduction on 'intrusion theory'(link in Wiki?) and the 'minimization of gravitational potential energy' . . . then explain the difference between (i) the usual Gulf-type mobile host salt domes/lava lamps and the continuum to(ii)the 'Flinders' brittle host model.
Finish with a comment on the importance of mobility and density (bouyancy) in the intruding medium, noting that an intrusion can be more dense or less dense than the host.
Introduce the idea of structurally-contolled passive/permitted (Flinders) intrusions to contrast with energetic/bouyant salt domes.
Add a photo example of a brittle-host intrusion, as well as the lava lamp.
Perhaps there are other experts (MIT?) who can contribute to a concise, useful, and high quality Wiki entry?
I'll go back to the rose garden. Tjmount ( talk) 21:42, 25 February 2009 (UTC)
Here is the link/reference to the 1975 work on diapirism in the Flinders Ranges that prompted many of the comments, above: http://web4.library.adelaide.edu.au/theses/09PH/09phm928.pdf Tjmount ( talk) 23:04, 25 February 2009 (UTC)
Great to have your input on this . . . thinking it through last night, what has really troubled me over the last 38 years is how the classic model for a diapir has become the 'US Gulf bouyant salt dome with bendy host' while the original Mrazec definition (1908, 1912) relates to breached (ie Greek 'pierced across') anticlinal cores under strong lateral compression and with a brittle host/overburden.
What we all need is a simple generic definition of 'an intrusion', then see how the Roumanian 'Type Location' diapirs fit into the classification . . . then ask if Gulf domes are really diapirs at all.
I avoided the problem in the Flinders Ranges, in 1975, by reference to 'salt breccia intrusions'. Tjmount ( talk) 00:25, 27 February 2009 (UTC)
As a small team of three, we may be approaching the limits of our expertise, reverting to personal comfort zones, with the potential for interesting but endless discussion?
We are wandering.
I began by suggesting that Marazec's original 'diapir' term may have been hijacked by Gulf Coast users (while not allowing for other types of intrusion) and admitted to needing a lot of help on the physics. AW's claimed strength is 'physics rather than salt tectonics', while MN is focused on salt rheology.
Lets' get back to defining the problem here and devise a plan of attack . . . as noted, above, the aim is to provide the average Wiki user with a fair and useful definition of 'diapirs'. So, is our work plan to: (i) to go back to Mrazec's original definition, (ii) review subsequent use, (iii) consult with current experts (eg Google . . . John K Warren, Mark G. Rowan, Vendeville & Jackson), (iv) draft a definition (and one that allows for uncertainty in scope), (v)obtain agreement, (vi) publish & maintain in Wiki?
Are there other readers who could have some input here? Tjmount ( talk) 21:24, 1 March 2009 (UTC)
And see my earlier (above)suggested layout for the Wiki note, but add 'the effect of regional compression'. Also need some nice diagrams, as well as the cursed lava lamp.
And apologies for all my poor spelling. Tjmount ( talk) 01:35, 2 March 2009 (UTC)
Hi...
As a worker in salt, extensional, and inversion tectonics, I thought I'd add my two cents..haha...
Do read papers by Vendeville and Jackson 1992 - The rise and fall of diapirs during extension...they are quite helpful and easy to read... This is another one that will talk about Trusheim (who first tried to understand this concept) www.beg.utexas.edu/presentations/2002_presentations/vendeville_gcags02.pdf
For all of the physics people in this group...Weijermars et al., 1993 - Rheological and tectonic modeling of salt provinces...that paper has loads of those diagrams you mentioned before...
The defination of a diapir is not as simple as it may seem, because it refers to both a process (diapirism) and a geologic structure (salt diapir- a salt mass that has flowed in a ductile manner to discordantly pierce or intrude its overburden; which again is really still refering to a process). Perhaps you may just want to call the article salt structures...then you can include diapirism, along with other structures like rollers, anticlines, salt glaciers, and allocthonous salt sheets, etc.
Heres alittle bit about diapirism...if you already didn't know... Extension can create "reactive diapirs"...they are reacting to the extension by upwelling along the fault (this is because of gravity...less overburden because extension thins .....but the salt mass does not "pierce the surface"...once diapirs the reach the surface, they are called "passive diapirs"...they will then continue to grow (downbuilding) until the source layer is depleted...It will be an "active diapir" for the hot second between reactive and passive when it breachs the surface...(see [ [5]] for a neat animation)
It's also important to mention, like the previous author who mentioned the North Sea, that salt tectonics, depends upon a number of parameters, all of which can vary depending on the region ( and even within the region). For example, salt structures in the Gulf of Mexico may look similar to salt structures elsewhere, but may be created by completely different tectonic processes...detached vs. basement-involved...but thats a conversation for later if interested..Or it can be a combination of both (eastern canada, morracco, brazil, North Sea, etc)...thats when it gets interesting...haha
I will try to write more with references in here. You can then decide which you would like to include in your article...
sorry I just read this...---->>>""In the process, segments of the existing strata can be disconnected and pushed upwards"") NOOOO!!!!!!). This is not what happens during diapirism. This implies that salt can do the pushing...try nailing a rubber "dowel" into a board. Salt is weak...it can only "displace" thick overburden when there is a regional tectonic trigger...I think that you should talk about diapirism in subheading of this article. It is very important, and also fairly simple to understand.
Nbgeo1 ( talk) 02:58, 21 May 2009 (UTC)
—Preceding
unsigned comment added by
Nbgeo1 (
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02:41, 21 May 2009 (UTC)
I just want to point out that the moon Enceladus belongs to Saturn, not Jupiter. I don't know whether the author meant "Saturn's moon Enceladus" or "Jupiter's moon Europa". Probably the latter, judging from the Europa article. —Preceding unsigned comment added by Poolio ( talk • contribs) 15:37, 13 October 2009 (UTC)
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OK - more to do. Need to separate the cold diapiric stuff from the hot diatremic stuff. Later - :-) Vsmith 12:53, 6 December 2005 (UTC)
Yeah, especially as diatremes are not diapirs. Rolinator 00:50, 22 December 2005 (UTC)
The original paper by Mrazec described diapirs from Roumania where salt cores have 'pierced across' and breached an overlying anticline. The folds are assymetric, compressive in style suggesting some 'tectonic energy' driving the intrusion. These pierced folds are very different to Gulf Coast salt domes.
Further, I don't believe that 'bouyancy' is essential for intrusion. The driving force for any intrusion is the weight of the adjacent overburden/cover which 'sinks' into the source layer, driven by gravity. The one factor that allows this release of gravitational energy is the MOBILITY of the intruding material. For example, sea water will rise up a hole/crack in an ice floe, forming an 'intrusion', yet the ice is less dense than the water otherwise the ice would sink. Even mercury will rise up a hole in a styrafoam block floating on it.
Sure, salt is less dense than typical host rocks/overburden, but its most important property, for intrusion, is its ability to flow(especially if wet and hot)in response to very low stresses. It is a time-dependant fluid, or 'rheid', rather like pitch/bitumen (and glass, marble etc). A tombstone (see old marble examples) or window (see glass in old cathedrals) of rock salt will droop and flow like treacle, given enough time
The lavalamp is a poor example of a 'diapir'.
A mobile intruding material that is LESS dense than the overburden simply has the potential to EXtrude (the cover sinks completely). If more dense, the intrusion will penetrate the cover to some point, then cease.
This is especially the case in extensive terrains where intrusion can be 'permitted' by tensional zones in the cover; even 'pull aparts' in compressive zones.
Forget about 'low density'; mobility is the key to intrusion.
Perhaps we should forget about 'diapirs' and just call them 'intrusions (salt, granite, shale, mud, breccia etc)'?
Cheers tmount 00:41, 27 February 2007 (UTC)
Appreciate comment on glass viscosity and withdraw reference to'cathedral windows' although input from a physicist on time-dependent fluids/viscosity or rheids would be useful. Salt is certainly a rheid, especially when wet/hot.
But it is my understanding that real-time measures of viscosity are meaningless in geological time frames . . . 'rheidity', or 'time-dependent viscosity' is the key, with flow of pitch being an example. Pure halite has 'no (measurable) ultimate shear strength', meaning it will flow, in time, in response to (any?) stress . . presumably a fly landing on it will eventually sink into the 'solid'. Even quicker for hot and wet salt. Expert input required here, and I am trying to recall research I did 38 years ago!
Tjmount (
talk)
20:27, 24 February 2009 (UTC)
Agree with most of your comments re layer instabilities etc, and the role of bouyancy in forming the classic US Gulf coast domes . . . and lava lamps.
However, my work was done in the Flinders Ranges of South Australia where the intruded host material was demonstrably unyielding and BRITTLE at salt emplacement (no Rayleigh-Taylor waves here), as evidenced by dyke wedging, roof grabens (extension normal to S1, bounding faults aligned parallel to S1=profile planes of anticlines), very sharp contacts with shape matching ('continental drift' style) across intrusions, stoped host blocks (to kilometres long = 'titaniclasts') etc. Instead of your 'holes' (above), I suggest the complex of intruding salt dykes were emplaced up S1/S2 structural planes, parallel to S1, normal to S3 principal stress directions, which at the regional scale was the direction of tectonic compression. Locally, the orientation of dyke planes varied with local stress field directions, giving complexity to the salt dyke swarms. In particular, smaller salt breccia dykes invade the two conjugate joint plane sets on the folds, as well as the usual axial and profile plane joints/faults. So where the overburden is thick, S2 is great and S3 becomes the direction of minimum stress . . . and even EXTENSION, as in the cores of massive Flinders Ranges regional anticlines.
Yes, I think you have got it . . . stuctural control, dykes into planes normal to S3=least or even tensional stress with extension as the dykes 'wedged' in as the fold grew under regional compression. Tjmount ( talk) 20:34, 24 February 2009 (UTC)
These are 'passive / permitted intrusions'
In a sence, the heavy fractured/blocky brittle overburden has foundered or sunk into the fluid salt layer, with the salt being further energised by lateral teconic/compressive forces.
I am trying to think of an example, but perhaps a glass of water filled mostly with crushed ice where the glass walls restrain lateral movement (ie 'tectonic forces') . . . the mobile (but, note, denser!)water rises and fills the voids between the clasts to a level way above 'isostatic' expectations.
Yes, I need help on this one and the glass model may not be the best. The point is, for a fractured brittle overburden, a mobile (but relatively dense, as for water up cracks in less dense/brittle ice breccia) material can move up a long way. Potentially to the surface where it 'extrudes' if it is less dense. How far vertically would a wet/hot (250deg C?)and mobile halite/anhydrite mush, with entrained dolostone/siliciclastic/dolerite clasts, intrude in a very thick (total to 40km) overburden of lithified rift sediments; as in the Flinders Ranges. First, on isostatic principles, then adding compressive energy? Think 'a salt -fluidised mush, based on a very poorly sorted 'fractal' breccia with clasts across a wide size range (dust to several km) such that the fines act as a mobile matrix (eg granular flow, like wheat) to larger clasts. Pore space could be as low as 10 to 15 % with the voids filled with 'fluid/plastic' salt which allows particle rotation and flow of the breccia. 'Salt rheidised/fluidised' in my terms. After emplacement, the mass cools, salt is leached out, and the intrusion becomes solid (with no obvious salt masses) in time, as in the Flinders Ranges. Zeolite facies cements (calcite, talc, silica, pure low-T adularia, magnesioriebeckite, dusty heamatite from dedolomitisation reactions during intrusion) etc lock up the breccias. Tjmount ( talk) 21:09, 24 February 2009 (UTC)
All this is very like Mrazec's Type 'diapirs' where salt has been injected across the cores of compressive folds.
There is a real need to rethink these mechanisms, towards the development of a 'grand unified theory if all intrusions' in which we can all insert our piece of the model.
Tjmount ( talk) 00:52, 23 February 2009 (UTC)
What my Flinders work showed was that all the traditional Gulf salt dome/lava lamp/Ramberg centrifuge thinking might not be the full story. In South Oz, at least, I became increasing nervous about geoworkers attributing every structural disruption, conglomerate, or facies change to the ubiquitous 'energetic punch up through the adjacent cover of a bouyancy driven low density salt 'diapir'.
Circular reasoning was common . . . 'here is a conglomerate . . . thus a diapir nearby . . . which must have shed conglomerates.
I quickly got a bad reputation by asking for proof that the conglometic clasts 'once were resident in a diapir'
Similarly, that latest trend is to attribute local facies changes in 'mini basins' to 'salt withdrawal and diapir emplacement' but this is not proof, especially where an active block faulted basement underlay the rift.
I could only see gentle, synteconic, passive emplacement of breccias of low salt content/low or higher density . . as above.
'Bouyancy' is something I have never really understood, like 'aerodynamic lift' over a wing. Seems we should get back to physical first principles (eg thermodynamics) and abandon comfortable assumptions.
It seems reasonable that all intrusions (diapirs, batholiths, salt domes, diatremes, igneous stocks, mid-oceanic dykes, lava lamps, mud up between the toes, sauces in puddings, C/Nimbus thunderheads/thermals, mantle plumes,) must all be driven by a single common set of simple principles (GUT of Intrusions). Glaciers and rivers probably follow the same rules, but upside down, air is the host, and more horizontal than vertical!
My challenge is to ask if the potential energy of a system can be lowered in a gravitational field by the migration of matter where mobility of the invading material is the key, subordinate to the effects of relative densities. Tjmount ( talk) 21:57, 24 February 2009 (UTC)
Importantly, the Wiki aim must be to provide good reliable information to a range of users, including those not so interested in acaddemic discussions.
So . . .
can we now EDIT the Wiki 'diapir' definition page to give an extended definition of intrusions (using modern concepts, based on your words, above) and show where 'diapirs' fit into the suite (and refer to Mrazec).
Begin with an introduction on 'intrusion theory'(link in Wiki?) and the 'minimization of gravitational potential energy' . . . then explain the difference between (i) the usual Gulf-type mobile host salt domes/lava lamps and the continuum to(ii)the 'Flinders' brittle host model.
Finish with a comment on the importance of mobility and density (bouyancy) in the intruding medium, noting that an intrusion can be more dense or less dense than the host.
Introduce the idea of structurally-contolled passive/permitted (Flinders) intrusions to contrast with energetic/bouyant salt domes.
Add a photo example of a brittle-host intrusion, as well as the lava lamp.
Perhaps there are other experts (MIT?) who can contribute to a concise, useful, and high quality Wiki entry?
I'll go back to the rose garden. Tjmount ( talk) 21:42, 25 February 2009 (UTC)
Here is the link/reference to the 1975 work on diapirism in the Flinders Ranges that prompted many of the comments, above: http://web4.library.adelaide.edu.au/theses/09PH/09phm928.pdf Tjmount ( talk) 23:04, 25 February 2009 (UTC)
Great to have your input on this . . . thinking it through last night, what has really troubled me over the last 38 years is how the classic model for a diapir has become the 'US Gulf bouyant salt dome with bendy host' while the original Mrazec definition (1908, 1912) relates to breached (ie Greek 'pierced across') anticlinal cores under strong lateral compression and with a brittle host/overburden.
What we all need is a simple generic definition of 'an intrusion', then see how the Roumanian 'Type Location' diapirs fit into the classification . . . then ask if Gulf domes are really diapirs at all.
I avoided the problem in the Flinders Ranges, in 1975, by reference to 'salt breccia intrusions'. Tjmount ( talk) 00:25, 27 February 2009 (UTC)
As a small team of three, we may be approaching the limits of our expertise, reverting to personal comfort zones, with the potential for interesting but endless discussion?
We are wandering.
I began by suggesting that Marazec's original 'diapir' term may have been hijacked by Gulf Coast users (while not allowing for other types of intrusion) and admitted to needing a lot of help on the physics. AW's claimed strength is 'physics rather than salt tectonics', while MN is focused on salt rheology.
Lets' get back to defining the problem here and devise a plan of attack . . . as noted, above, the aim is to provide the average Wiki user with a fair and useful definition of 'diapirs'. So, is our work plan to: (i) to go back to Mrazec's original definition, (ii) review subsequent use, (iii) consult with current experts (eg Google . . . John K Warren, Mark G. Rowan, Vendeville & Jackson), (iv) draft a definition (and one that allows for uncertainty in scope), (v)obtain agreement, (vi) publish & maintain in Wiki?
Are there other readers who could have some input here? Tjmount ( talk) 21:24, 1 March 2009 (UTC)
And see my earlier (above)suggested layout for the Wiki note, but add 'the effect of regional compression'. Also need some nice diagrams, as well as the cursed lava lamp.
And apologies for all my poor spelling. Tjmount ( talk) 01:35, 2 March 2009 (UTC)
Hi...
As a worker in salt, extensional, and inversion tectonics, I thought I'd add my two cents..haha...
Do read papers by Vendeville and Jackson 1992 - The rise and fall of diapirs during extension...they are quite helpful and easy to read... This is another one that will talk about Trusheim (who first tried to understand this concept) www.beg.utexas.edu/presentations/2002_presentations/vendeville_gcags02.pdf
For all of the physics people in this group...Weijermars et al., 1993 - Rheological and tectonic modeling of salt provinces...that paper has loads of those diagrams you mentioned before...
The defination of a diapir is not as simple as it may seem, because it refers to both a process (diapirism) and a geologic structure (salt diapir- a salt mass that has flowed in a ductile manner to discordantly pierce or intrude its overburden; which again is really still refering to a process). Perhaps you may just want to call the article salt structures...then you can include diapirism, along with other structures like rollers, anticlines, salt glaciers, and allocthonous salt sheets, etc.
Heres alittle bit about diapirism...if you already didn't know... Extension can create "reactive diapirs"...they are reacting to the extension by upwelling along the fault (this is because of gravity...less overburden because extension thins .....but the salt mass does not "pierce the surface"...once diapirs the reach the surface, they are called "passive diapirs"...they will then continue to grow (downbuilding) until the source layer is depleted...It will be an "active diapir" for the hot second between reactive and passive when it breachs the surface...(see [ [5]] for a neat animation)
It's also important to mention, like the previous author who mentioned the North Sea, that salt tectonics, depends upon a number of parameters, all of which can vary depending on the region ( and even within the region). For example, salt structures in the Gulf of Mexico may look similar to salt structures elsewhere, but may be created by completely different tectonic processes...detached vs. basement-involved...but thats a conversation for later if interested..Or it can be a combination of both (eastern canada, morracco, brazil, North Sea, etc)...thats when it gets interesting...haha
I will try to write more with references in here. You can then decide which you would like to include in your article...
sorry I just read this...---->>>""In the process, segments of the existing strata can be disconnected and pushed upwards"") NOOOO!!!!!!). This is not what happens during diapirism. This implies that salt can do the pushing...try nailing a rubber "dowel" into a board. Salt is weak...it can only "displace" thick overburden when there is a regional tectonic trigger...I think that you should talk about diapirism in subheading of this article. It is very important, and also fairly simple to understand.
Nbgeo1 ( talk) 02:58, 21 May 2009 (UTC)
—Preceding
unsigned comment added by
Nbgeo1 (
talk •
contribs)
02:41, 21 May 2009 (UTC)
I just want to point out that the moon Enceladus belongs to Saturn, not Jupiter. I don't know whether the author meant "Saturn's moon Enceladus" or "Jupiter's moon Europa". Probably the latter, judging from the Europa article. —Preceding unsigned comment added by Poolio ( talk • contribs) 15:37, 13 October 2009 (UTC)
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What exactly *is* differential loading? It's a redlink, and I can't find anything relevant on a pretty thorough set of searches. 172.4.121.7 ( talk) 01:09, 21 March 2023 (UTC)