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prcantos
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Joined: 17 Apr 2012
Posts: 243
Location: Granada (Spain)
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Posted: Jun 03, 2013 08:24 Post subject: Genesis of the serpentine minerals and rocks |
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Hi. Recently in the Spanish-side FMF-Forum we have been discussing about a pyrope-bearing serpentinite whose serpentine-mineral could have been originated by the serpentinization of the pyroxenes of a previous eclogite. (You can see this serpentine rock in the picture below).
I was really surprised or annoyed because of these presumed serpentinized pyroxenes, which led me to further readings. I would like to know your opinions about this topic: processes of (non-metasomatic) serpentinization. If you prefer, you can use these questions to arrange the information:
[1] Is it possible that Mg-pyroxenes, Mg-amphiboles (or even Mg-silicates in general) become serpentine minerals? If so, what conditions do these processes require?
[2] Do basic igneous rocks (not ultramafic) or eclogites become serpentinites? If so, what conditions are required?
Thank you.
Description: |
Serpentine and pyrope Zöblitz, Erzgebirge, Sachsen, Germany 8 cm. FOV A serpentinized eclogite? |
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_________________ Pablo Rodríguez Cantos
Λίθον˛ον απεδοκίμασαν˛οι οικοδομουντες |
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Roger Warin
Joined: 23 Jan 2013
Posts: 1194
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Posted: Jun 03, 2013 10:32 Post subject: Re: Genesis of the serpentine minerals and rocks |
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Hello Pablo, list,
This transformation of Mg- (also Fe-) pyroxene in serpentine is observed in meteorites. The presence of water is essential. Are concerned some meteorites from Mars and also those who have always been "cold", that is to say at a temperature below 100 ° C, as the CI and CM carbonaceous chondrites. Water-bearing, clay-rich silicates like smectite (montmorillonite) and serpentine-like minerals do occur under aqueous alteration.
Martian meteorites (as Nakhla) show significant impact heating and pressures. Water was once present on Mars. Hydrothermal processes occurred. Scientists say serpentine mineralization is associated with a production of methane.
Roger.
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prcantos
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Joined: 17 Apr 2012
Posts: 243
Location: Granada (Spain)
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Posted: Jun 06, 2013 04:48 Post subject: Re: Genesis of the serpentine minerals and rocks |
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Thank you, Roger. Really interesting information.
_________________ Pablo Rodríguez Cantos
Λίθον˛ον απεδοκίμασαν˛οι οικοδομουντες |
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