Dear Bernardo and all,
this is a tantalizing question, especially with respect to the stability
or metastability of diaspore with quartz in (meta)sediment.
The assemblage has a high-pressure stability field in place of
pyrophyllite, with some relevant records from Nature, but what about the
diaspore occurring in Proterozoic quartzites of North America?!
References for both instances and to earlier discussions may be found
in Theye et al., 1997, JMG, 15, 17-28, attached.
Cheers
Christian
---
Christian Chopin [log in to unmask]
Laboratoire de Géologie
Ecole normale supérieure - CNRS UMR8538
24 rue Lhomond
75231 PARIS CEDEX 05
France
Le 2021-07-01 09:47, Bernardo Cesare a écrit :
> Dear all,
> I am looking for references about natural examples of diaspore
> occurrence in phyllites.
> Is diaspore present/common in low-grade metapelites? I would argue it
> requires some sort of unusual weathering of the sediment before
> metamorphism.
> Can anyone comment on this issue?
>
> Thanks in advance, and have a nice Summer!
>
> Bernardo
>
> --
>
> *******************************************************************
> Bernardo Cesare
> Dipartimento di Geoscienze, Universita' di Padova
> Via G. Gradenigo, 6, I-35131 PADOVA ITALY
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> InsiemePerWamba: http://www.insiemeperwamba.org
> *******************************************************************
>
> "The only real failure is the failure to try, and the measure of
> success
> is how we cope with disappointment, as we always must."
> From the
> movie: The Best Exotic Marigold Hotel
>
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