Yes, this seems to be a general feature.
Three papers which discuss the effect are (grabbed out of Georef)
Garnet-quartz intergrowths in graphitic pelites; the role of the fluid
phase.
Burton-K-W
Mineralogical Magazine. 50, Pages 611-620. 1986.
Porphyroblast textural sector zoning and matrix displacement.
Rice-A-H-N; Mitchell-J-I
Mineralogical Magazine. 55; 380, Pages 379-396. 1991.
Textural and twin sector-zoning and displacement of graphite in
chiastolite and pyralspite and granite garnets in the Variscides of
South-west England.
Rice-A-H-N
Proceedings of the Ussher Society. 8, Part 2; Pages 124-131. 1993.
Dave Waters
Charles V. Guidotti wrote:
>
> Dear all, March 1, 1999
> In the course of doing a fair amount of thin section petrography on
> metapelitic rocks, I have looked at a number of graphite-rich and
> graphite-poor samples collected from essentially the same outcrop (biotite
> into sillimanite zones). I have noticed that the presence of abundant modal
> graphite (say, greater than 1+ %, so that it noticably starts to affect the
> groundmass color) in a metapelite seems to have an obvious, pronounced
> effect on the nature of the textures seen in one rock versus the other. I
> expect that others have made this same observation because I rather doubt
> that I've been looking at any rocks that are in some way unique or special.
>
> I'm curious to hear, have other petrographers have made a similar
> observation? If so, does anyone have any suggestions why such an effect
> occurs? Also, does anyone know if this has been discussed specifically
> anywhere in the literature?
> Many thanks for any input that can be provided on my questions.
>
> Cheers,
> Chuck Guidotti
--
Dave Waters - Lecturer in Metamorphic Petrology, Oxford University
Dept of Earth Sciences, Parks Rd, Oxford OX1 3PR, UK
Tel: +44 1865 272000
Direct: +44 1865 272058 Email: [log in to unmask]
Fax: +44 1865 272072 http://www.earth.ox.ac.uk/~davewa/
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