Talk:Metamorphism
From Wikipedia, the free encyclopedia
 |
Metamorphism is part of WikiProject Geology, an attempt at creating a standardized, informative, comprehensive and easy-to-use geology resource. If you would like to participate, you can choose to edit this article, or visit the project page for more information. |
| Start | This article has been rated as Start-class on the quality scale. |
| High | This article has been rated as High-importance on the importance scale. |
Redirects: Metamorphism (geology), Regional metamorphism, Contact metamorphism, Hydrothermal metamorphism, Impact metamorphism
Removed redirect because i intend to write something about this. Muriel Gottrop 15:25, 1 Aug 2003 (UTC)
The concept of metamorphic sequence is missing:
- pelitic sequence (where the concept of metamorphic zones -chlorite, biotite, garnet, staurolite, kyanite, sillimanite- is usually applied)
- mafic (or basic) sequence (where the concept of facies is usually applied
- ultramafic (or ultrabasic) sequence
- Carbonate sequence
- Quartzo-feldspathic sequence
- ...
Also the term of Barrovian metamorphism for regional metamorphism should be added
Moumine 23:32, 15 Mar 2005 (UTC)
Barrovian metamorpism is only one type of prograde sequence, and it is wrong to class blueschist and eclogite in with it. Also, I will attempt to work on a more thorough definition of metamorphic facies which includes what they are, mineral assemblages, etc. Also, I can't believe that prehnite-pumpellyite facies was missing entirely....oh well. Rolinator 05:52, 24 December 2005 (UTC)
Done Blueschist facies, under Blueschist and Greenschist facies under Greenschist and Amphibolite Facies under Amphibolite. Will also be attempting to bring together the materials science links to put together the whole equilibrium assemblage thing; also the thermomechanical reasons behind metamorphism, and work on rock microstructure metamorphic section as part of this. Rolinator 08:51, 27 December 2005 (UTC)
[edit] Dynamic metamorphism
Dynamic metamorphism should not be confusedwith brecciation; the former is a metamorphic event (thermal and textural) and the latter is just a result of faulting. In brittle conditions, you are unlikely to see any change of mineral assemblages, because the rocks are too cool to undergo retrogression. I'll grant that a lot of large fault systems have clay gouges etc, in the upper crustal zones, but most of this is a result of metasomatism not metamorphism.
Dynamothermal metamorphism is also not to be confused with mylonitisation; mylonites are a textural response to ductile deformation, resulting in comunition via grain size reduction and mineral reconfiguration, most often without changing the mineral assemblage. That's not metamorphism, it's shearing. The other problem with confabulating mylonites and dynamothermal metamorphism is that mylonites don't neccessarily get heated up enough above the background because shear dislocation is shared across a very large cross section of he shear zone. In the brittle-ductile transition, however, heat is able to be focused more efficiently into thin fault zones because the confining pressure keeps the hangingwall and footwall pressed together enough to mitigate milling, and the rock isn't ductile enough to deform via pure ductile smearing...so it tends to, in the rare cases, form thick shear bands of pseudotachlyltes and disturbed milled ductile melanges and fault gouges. In these zones the frictional heat is often enough to not only heat the rock up to melt it, but also change the mineral assemblage, hence causing definite metamorphism not just textural reorganisation.Rolinator 04:08, 23 April 2006 (UTC)
we need some diagrams to get towards a B class Graeme Bartlett 06:16, 9 November 2007 (UTC)
