Dear Mauricio,

I believe that you could find some ideas about 
your problem looking for the literature about the 
metasomatic shear zones affecting granitoids. 
There is quite some literature from the Alps 
(some refs. - non exhaustive - pasted below), 
particularly concerning the whiteschists and the 
so-called leucophyllites.

I have seen similar rocks in the Armorican 
massif. One of them is described in this paper:

Pitra, P., Boulvais, P., Antonoff, V. & Diot, H., 
2008. Wagnerite in a cordierite-gedrite gneiss: 
Witness of long-term fluid-rock interaction in 
the continental crust (Ile d'Yeu, Armorican 
Massif, France). American Mineralogist, 93, 
315-326.

Not really a phyllonite, but other shear-zones 
from the region could be classified as 
"phyllonites" (biotite dominated schists, locally 
with garnet or staurolite, forming "bands" in the 
granitoids); we are working on them and I hope 
we'll manage to publish something in the near 
future.

Good luck!

All the best,

Pavel

some references (no particular order):

Selverstone, J., Morteani, G. & Staude, J.-M., 
1991. Fluid chanelling during ductile shearing: 
transformation of granodiorite into aluminous 
schist in the Tauern Window, Eastern Alps. 
Journal of Metamorphic Geology, 9, 419-431.

Sassier, C., Boulvais, P., Gapais, D., Capdevila, 
R. & Diot, H., 2006. From granitoid to 
kyanite-bearing micaschist during fluid-assisted 
shearing (Ile d'Yeu, France). International 
Journal of Earth Sciences, 95, 2-18.

Oliot, E., Goncalves, P. & Marquer, D., 2010. 
Role of plagioclase and reaction softening in a 
metagranite shear zone at mid-crustal conditions 
(Gotthard Massif, Swiss Central Alps). Journal of 
Metamorphic Geology, 28, 849-871.

Chopin, C., Henry, C. & Michard, A., 1991. 
Geology and petrology of the coesite-bearing 
terrain, Dora Maira massif, Western Alps. 
European Journal of Mineralogy, 3, 263-291.

Demény, A., Sharp, Z. D. & Pfeifer, H.-R., 1997. 
Mg-metasomatism and formation conditions of 
Mg-chlorite-muscovite-quartzphyllites 
(leucophyllites) of the Eastern Alps (W. Hungary) 
and their relations to Alpine whiteschists. 
Contributions to Mineralogy and Petrology, 128, 
247-260.

Pawlig, S. & Baumgartner, L. P., 2001. 
Geochemistry of a talc-kyanite-chloritoid shear 
zone within the Monte Rosa granite, Val d'Ayas, 
Italy. Schweizerische mineralogische und 
petrographische Mitteilungen, 81, 329-346.

Ferrando, S., Frezzotti, M. L., Petrelli, M. & 
Compagnoni, R., 2009. Metasomatism of continental 
crust during subduction: the UHP whiteschists 
from the Southern Dora-Maira Massif (Italian 
Western Alps). Journal of Metamorphic Geology, 
27, 739-756.

Goncalves, P., Oliot, E., Marquer, D. & Connolly, 
J. A. D., 2012. Role of chemical processes on 
shear zone formation: an example from the Grimsel 
metagranodiorite (Aar massif, Central Alps). 
Journal of Metamorphic Geology, 30, 703-722.

Ferrando, S., 2012. Mg-metasomatism of 
metagranitoids from the Alps: genesis and 
possible tectonic scenarios. Terra Nova, 24, 
423-436.


----

>Hello to all,
>This is only my second email to this list and 
>the discussion about metassomatism and open 
>chemical system came at the right time for me, 
>and I would like to ask for some suggestions for 
>the list members.
>I work at the Geological Survey of Brazil and we 
>are mapping a region in SW Brazil, where it is 
>difficult to separate Paleoproterozoic granitic 
>bodies from the deformed basement. A common 
>feature in the region are bodies of ms-qtz 
>schists with porphyroblasts of garnet schists 
>with 1-2cm  wide, in contact with granitic 
>bodies.This schist was first described as a 
>metassedimentary unit. However the features of 
>the field indicate that this rock represents 
>filonites from the granitic bodies.
>There are publications that discuss the 
>formation of filonites under the chemical point 
>of view?
>Where I could find another examples similar to what we see in this region?
>
>Apologies if i made some mistakes in the text,
>
>Thanks for your attention,
>
>Mauricio Pavan Silva
>Geologist - Geological Survey of Brazil/CPRM
>
>


-- 
Pavel PITRA
Géosciences Rennes			email: [log in to unmask]
Université Rennes 1			tel: (++33) 2.23.23.65.06
Campus de Beaulieu - Bat. 15		fax: (++33) 2.23.23.60.97
F - 35 042 RENNES CEDEX
FRANCE				http://www.geosciences.univ-rennes1.fr/
http://www.geosciences.univ-rennes1.fr/spip.php?article67