Garnet-hornblende-epidote-phengite-rutile-quartz rock will work also.
On 17/12/2014, Santanu Kumar Bhowmik <[log in to unmask]> wrote:
> Dear Colleagues,
>
> I am seeking your suggestions on the nomenclature of a metamorphic rock with
> the assemblage garnet+hornblende+epidote+phengite+rutile+quartz. This
> assemblage which became stable during peak metamorphism yielded P-T estimate
> of ~ 15-16 kbar,~ 590-610 °C. If this assemblage is evaluated with
> metamorphic rocks that are related to metamorphism during subduction
> initiation, the closest rock name that comes to my mind is garnetiferous
> amphibolite. However, in the strictest sense, the rock, in the absence of
> plagioclase cannot be an amphibolite, if we use amphibolite in facies sense.
> At the same time, the estimated P-T range lies in the eclogite facies, also
> supported in part by complete elimination of plagioclase. However, with
> omphacitic clinopyroxene being absent, the rock is also not an eclogite in
> the strictest sense. One additional information in this regard is that Na in
> the protolith is completely partitioned in Hbl, which shows substantial
> presence of Na in the M4 site, apart from its general occurrence in the A
> site.
>
> Your comments and observations are welcome.
>
> With regards,
>
> Santanu
> -------------------------------------------------------
> Dr. Santanu Kumar Bhowmik
> Professor
> Department of Geology & Geophysics
> Indian Institute of Technology
> Kharagpur-721 302
> India
> Mobile:+919434041791
> Telephone:+91-3222-283390(O), 283391, 279766(R)
>
--
Professor J. Stephen Daly
Head of School and Director, National Centre for Isotope Geochemistry
UCD School of Geological Sciences
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University College Dublin, Belfield
Dublin 4, Ireland.
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