Dear Abu Bakarr,
From my point of view, in deep-seated rocks, metamorphism and
hydrothermal alteration (or metasomatism) are intimately linked. The
difference between metamorphism and metasomatism resides in the scale at
which mass transfers are considered. Metamorphism describes phase
transitions and mass transfers in a chemically closed system whereas
metasomatism (associated with hydrothermal alteraion) applies in the
case of an chemically open system.
We investigated the relationships in a recent paper :
Eglinger A., Ferraina C., Tarantola A., André-Mayer A.-S., Vanderhaeghe
O., Boiron M.-C., Dubessy J., Richard A., Brouand M. (2014). Metamorphic
evolution of U-bearing highly saline Ca-Na fluids in syntectonic
Pan-African quartz veins in the Domes region (Lufilian belt, Zambia).
Contributions to Mineralogy and Petrology. 167, 967-995
An additional paper will be published on this topic in a coming issue of
Chemical Geology:
Eglinger A., Tarantola A., Durand C., Ferraina C., Vanderhaeghe O.,
André-Mayer A-S., Paquette J.-L., Deloule E. (revised version
submitted). Uranium mobilization by fluids associated with Ca-Na
metasomatism: a P-T-t record of fluid-rock interactions during
Pan-African metamorphism (Western Zambian Copperbelt). Chemical Geology.
Here is how we introduced the topic (this gives you also usefull
references):
"Mineral assemblages and fluid inclusions 42 are first hand witnesses of
fluid circulations and associated fluid-rock interactions (Ague, 1994a
,b, 1997) driven by deformation and gradients of pressure, temperature
and chemical potential (Wood and Walther, 1983; Walther and Wood, 1984;
Putnis, 2009; Putnis and Austrheim, 2010). Fluid flow and mass transfer
at the mineral scale drive metamorphism, leading to metasomatism in case
of a chemically open system at the rock scale (Carmichael, 1969;
Etheridge et al., 1983; Philpotts and Ague, 2009; Putnis and Austrheim,
2010). During prograde P-T paths, metamorphic fluids are produced by
devolatilization reactions such as dehydration and/or decarbonation and
are thus potential agents of metasomatism at the mineral to rock scale
(Chinner, 1967; Yardley and Baltatzis, 1985; Ferry, 1992; Ague, 1994a,
b, 1997; Oliver et al., 1998)."
Best regards,
Olivier Vanderhaeghe.
Le 21/07/2014 03:36, B a écrit :
> Dear all,
> I'm facing a challenge on the dichotomy btw hydrothermal alternation and metamorphism. I think they are the different, a colleague of mine think they are the same.
> Are they the same or different?
> Any published article clearly explaining these two processes to a young researcher is highly appreciated.
> Regards,
> Abu Bakarr.
>
--
Olivier VANDERHAEGHE
Geosciences-GéoRessources
Universite de Lorraine
BP 239, 54506 Vandoeuvre les Nancy
France
+33 (0) 3 83 68 47 34
http://www.geologie.uhp-nancy.fr/Php/index.php
http://www.g2r.uhp-nancy.fr/annuaire/vanderhaeghe.html
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