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Activity–composition relations for the calculation of partial melting equilibria in metabasic rocks
Author(s) -
Green E. C. R.,
White R. W.,
Diener J. F. A.,
Powell R.,
Holland T. J. B.,
Palin R. M.
Publication year - 2016
Publication title -
journal of metamorphic geology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.639
H-Index - 114
eISSN - 1525-1314
pISSN - 0263-4929
DOI - 10.1111/jmg.12211
Subject(s) - partial melting , hornblende , silicate , granulite , composition (language) , geology , phase (matter) , thermodynamics , geochemistry , mineralogy , chemistry , biotite , physics , facies , mantle (geology) , paleontology , linguistics , quartz , philosophy , organic chemistry , structural basin
A set of thermodynamic models is presented that, for the first time, allows partial melting equilibria to be calculated for metabasic rocks. The models consist of new activity–composition relations combined with end‐member thermodynamic properties from the Holland & Powell dataset, version 6. They allow for forward modelling in the system Na2 O–CaO–K2 O–FeO–MgO–Al2 O3 –SiO2 –H2 O–TiO2 –Fe2 O3 . In particular, new activity–composition relations are presented for silicate melt of broadly trondhjemitic–tonalitic composition, and for augitic clinopyroxene with Si–Al mixing on the tetrahedral sites, while existing activity–composition relations for hornblende are extended to include K2 O and TiO2 . Calibration of the activity–composition relations was carried out with the aim of reproducing major experimental phase‐in/phase‐out boundaries that define the amphibolite–granulite transition, across a range of bulk compositions, at ≤13 kbar.