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.
[cid:973ca7d2-bacf-4e53-8dd7-ba2d15c4511e]
Cheers,
Victor
________________________________
From: Metamorphic Studies Group <[log in to unmask]> on behalf of Sebastián Verdecchia <[log in to unmask]>
Sent: Thursday, March 1, 2018 4:18:02 PM
To: [log in to unmask]
Subject: Re: identifying altered cordierite
Hi all, In addition to Dave's comments, in the last images from pdf file that attached Carl, is possible to observed haloes surrounding zircons (?).
On the other hand, we recognized And/Cd post-St/Gr/Ky in micaceous schist from Sierra de Ancasti of Argentina and interpreted as a decompression stage, from 590º-5kb to ca. 560-3.5 kb (Verdecchia et al JMG 2013, 31, 131-146).
Regards,
Sebastián
2018-03-01 17:39 GMT-03:00 David Waters <[log in to unmask]<mailto:[log in to unmask]>>:
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]<mailto:[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:[log in to unmask]<mailto:[log in to unmask]>] On Behalf Of Bernardo Cesare
Sent: 01 March 2018 20:36
To: [log in to unmask]<mailto:[log in to unmask]>
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
Dipartimento di Geoscienze, Universita' di Padova
Via G. Gradenigo, 6, I-35131 PADOVA ITALY
Tel: ++39-049-8279148 Fax: ++39-049-8279134
email: [log in to unmask]<mailto:[log in to unmask]>
Web site: http://147.162.183.153/bernardo/berning.html
ACME Group: http://147.162.183.153/ACME
MicROCKScopica: http://www.microckscopica.org
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
--
Dr. Sebastián O. Verdecchia
CICTERRA (CONICET - UNC)
Facultad de Ciencias Exactas, Físicas y Naturales
Universidad Nacional de Córdoba
Av. Velez Sarsfield 1611. CICTERRA (Piso 2, oficina 2)
CP: X5016GCA - Córdoba (Capital)
Tel.: +54-351-5353800 (int 30218)
Provincia de Córdoba - Argentina
CICTERRA: http://cicterra.conicet.unc.edu.ar/
