Hello,
I would not say that it is the same. composition
isopleth is a line of a constant value of ONE
COMPOSITIONAL VARIABLE, which may be e.g. the
grossular proportion of garnet (as Richard
wrote), but also commonly e.g. the XFe of a
mineral or the amount of the Tschermak
substitution (i.e. something that does NOT
directly correspond to the amont of an end-member)
The modal isopleths are lines of identical MOLE
proportion of a specific PHASE (garnet,
staurolite, biotite,...). Calculated, not
estimated.
Cheers,
Pavel
--
>"Modal" is modal, that is to say the estimated
>mineral proportions. "Composition" is the same
>but for mineral composition !
>Cheers
>Nuno Leal
>
>De: Metamorphic Studies Group
>[mailto:[log in to unmask]] Em nome
>de john ponting
>Enviada: quarta-feira, 30 de Janeiro de 2013 09:46
>Para: [log in to unmask]
>Assunto: Pseudosection Help
>
>Dear All,
> Perhaps it my be a very silly
>question. what is the definition of the Modal
>and Composition isopleths.
>
>Thank you in advance
>with warm regards,
>J Ponting
--
Pavel PITRA
Géosciences Rennes email: [log in to unmask]
Université Rennes 1 tel: (++33) 2.23.23.65.06
Campus de Beaulieu - Bat. 15 fax: (++33) 2.23.23.60.97
F - 35 042 RENNES CEDEX
FRANCE http://www.geosciences.univ-rennes1.fr/
http://www.geosciences.univ-rennes1.fr/spip.php?article67
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