Another example of what appears to be crd after st in the Appleton Ridge Formation, Maine, USA, from a sample collected by Dave West. Strange rocks indeed.
Cheers,
Victor
Just what I was thinking!
Needs a clockwise P-T path.
Later Crd/And in St schist can happen in the Lhotse schists on Mt Everest, which loop through 5.5 kbar, peak in low 600s, return via ~3 kbar
Waiting for Dave Pattison now ...
Dave
Dave Waters, Metamorphic Petrologist
(1) Department of Earth Sciences, South Parks Rd, Oxford OX1 3AN
(2) University Museum of Natural History, Parks Rd, Oxford OX1 3PW
Email: [log in to unmask] Tel: +44 1865 272000
http://www.earth.ox.ac.uk/~davewa/ Direct: +44 1865 282457
------------------------------------------------------------ -----Original Message-------------
From: Metamorphic Studies Group [mailto:GEO-METAMORPHISM@JISCMAIL.AC.UK ] On Behalf Of Bernardo Cesare
Sent: 01 March 2018 20:36
To: [log in to unmask]UK
Subject: Re: [geo-metamorphism] identifying altered cordierite
Carl
quite interesting because St-Crd isn't a typical barrovian assemblage and is quite uncommon.
I guess Dave Pattison will want to comment on this.
Bernardo
> <!-- p { margin-top: 0px; margin-bottom: 0px; }--> Dear metamorphic
> community,
>
>
>
> We're working on a suite of archean paragneiss (Opinaca
> subprovince, Superior Craton) that display a barrovian-type sequence
> of isograds (bt-gt-st-sill). In the field, we have noticed a
> blueish-greenish mineral in the pressure shadows of early kinematic
> staurolite, and thought it's either chlorite or cordierite. However,
> in thin section, the mineral has clearly been altered and shows a
> heterogeneous chemical composition (see attached document for pictures and probe analyses).
>
>
>
> We are looking for ways to confirm or infirm that the altered mineral
> was once cordierite.
>
>
>
> Any comments/advice/references will be greatly appreciated.
>
>
>
> Best regards
>
>
>
> Carl and Myriam
> ____________________________________________
>
> Carl Guilmette, PhD. Eng.
> Professeur Adjoint
> Chaire de Leadership en Enseignement Virginia-Gaumond Département de
> Géologie et Génie Géologique Université Laval
> 1-418-656-2131 poste 3137
--
************************************************************ *******
Bernardo Cesare
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