I've just had a paper published!
No particular cause for celebration you may well say - but I rather
like this one, and it connects with 'metamorphism in the mantle',
which I seem to remember we touched on rather late on the evening of
Colin's retirement do.
The current paper (co-author Steve Richardson from Cape Town) is hard
on the heels of a previous one (which strictly has most of the
memorphism in it) and so I'm cluttering your mailbox by sending both.
The reason I like them is because they give diamonds with deep
(>300kms) inclusions a place of origin and use them to trace the
history of a subducted (stagnant) slab beneath western Gondawana in
Nice to talk with you a couple of weeks ago.
Have a good Christmas and happy New Year.
Quoting Bruce Yardley <[log in to unmask]> on Mon, 20 Jul 2009
> Dear Reia
> I think you should bear in mind that the sort of reactions that
> produce garnet porphyroblasts with inclusions are invariably
> devolatilisation reactions, and almost invariably dehydration
> reactions. So it is very unlikely that fluid availability varies
> significantly in different places unless the rock types and garnet
> chemistry are really very different - the fluid pressure is close to
> lithostatic and the permeability and "porosity" reflect the rate of
> heat supply after the initial boost of nucleation (and are
> inexorably coupled to the reaction rate). In my view, fluid
> parameters in prograde metamorphism (as opposed to metasomatism) are
> not normally independent variables but are constrained by
> temperature, depth, salinity, rock composition and to some extent
> heating rate.
> There are other factors which undoubtedly have a large impact on the
> density of solid inclusions. Have you checked out Dugald
> Carmichael's classic work on porphyroblasts in which he argued
> (incorrectly!) that Al is immobile but illustrated very clearly that
> a porphyroblast growing in a layer whose bulk composition is close
> to that of the porphyroblast will contain fewer solid inclusions
> than one growing in a layer with a more distinct composition? This
> is most apparent when you look at quartz inclusions - see also for
> example sample 91 (p.94) in my Atlas of Metamorphic Rocks in Thin
> Section. But inclusion density can also vary between core and rim
> suggesting a growth rate control, especially where the reaction
> stoichiometry has changed through time.
> Professor Bruce Yardley
> School of Earth and Environment
> University of Leeds
> Leeds LS2 9JT, UK
> Tel: +44 (0)113 3435227
> Fax: +44 (0)113 3435259
> -----Original Message-----
> From: Metamorphic Studies Group
> [mailto:[log in to unmask]] On Behalf Of Reia M.
> Sent: 20 July 2009 11:06
> To: [log in to unmask]
> Subject: Re: fluids dictating mineral inclusion density in garnet?
> Hi Reiner,
> Thank you, but these seem to be on fluid inclusions. I am looking
> for how fluids influence the presence or absence of mineral
> inclusions in garnet (e.g. by acting as a "flux" to push other
> minerals out of the way as garnet grows).
> At 08:04 20/07/2009, you wrote:
>> Hi Reia,
>> just check
>> Vry & Brown, 1991, CMP, 108, 271-282.
>> Whitney et al., 1996, JMG, 14, 163-181.
>> Kaindl & Abart, 2002, SMPM, 82, 467-486
>> Cheers, Reiner
Ben Harte (Prof)
Grant Institute of Earth Sciences,
School of GeoSciences, University of Edinburgh,
Edinburgh EH9 3JW.
Tel:  (0)131 651 7220; Fax:  (0)131 668 3184
The University of Edinburgh is a charitable body, registered in
Scotland, with registration number SC005336.