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Hi Nuno, Thanks for your critical advise! Still I think that in this case I can trust the models as indeed staurolite occurs also inside the pseudomorphs! But you are right, especially in those large systems (I used MnNCKFMASHTO) small variations in bulk chemistry have a dramatic impact! Thank you very much! Cheers Simon Am 14.09.2015 19:49, schrieb Nuno Leal: > > Dear Simon: > > You must be careful about the real meaning of pseudo-sections, as > sometimes, minor components can strongly affect equilibria… > > Besides that, I think you may be right. Overprinting like that is > surely a common phenomenon. > > Is there any sample in which you can see staurolite relicts ? > Otherwise, I think that it will be difficult to confirm your hypothesis. > > The fact that pseudomorphs are sometimes present and sometimes absent > could reflect different speeds of crystallisation. > > Cheers > > Nuno > > *De:*Metamorphic Studies Group > [mailto:[log in to unmask]] *Em nome de *Simon > *Enviada:* 13 de setembro de 2015 18:38 > *Para:* [log in to unmask] > *Assunto:* Chloritoid Pseudomorphs > > Dear all, > > In the study area for my masterthesis (southern Saualpe, Eastern Alps) > large prismatic chloritoid pseudomorphs occur in a (lower) amphibolite > grade g-st-ctd-chl-paragonite micaschist. Inside the pseudomorphs fine > grained sericite as well as paragonite are common (please see the > attached figure). > I suspect that they are replacement products after coarse-grained > staurolites which seem to have grown during prograde permian HT/LP > metamorphism (~600°C & 6kbar) as shown by pseudosection modelling. > After that, the rocks were overprinted by the eoalpine HP/LT > metamorphism where I think the replacement occured, as the prograde > path lies largely within the ctd-stabilityfield and outside the st-field. > > The pseudomorphs occur only in a restricted locality, although rocks > with virtually the same composition occur nearby, showing the same > paragensis but lacking the pseudomorphs. In this case staurolite of > eoalpine generation is in equilibrium with chloritoid (as it is also > in the samples with the pseudomorphs), but, the striking pseudomorphs > are lacking. > > I'd like to investigate the replacement further, can you please give > me a hint how to proceed? Or is there maybe a paper where such > microstructures have been described? > > I am thankful for every thought! > > Thank you very much! > > Cheers > > Simon > > > ctd-pseudomorph.jpg >