HPx-eos: metabasite set

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General information

Citation: Green, ECR, White, RW, Diener, JFA, Powell, R, Holland, TJB & Palin, RM (2016). Activity-composition relations for the calculation of partial melting equilibria in metabasic rocks. Journal of Metamorphic Geology 34 845-869.

Phases:

PhaseAlso in setsFirst published
silicate meltthis paper
hornblende, actinolite and glaucophaneigneousthis paper
augitic clinopyroxenethis paper
jadeite-omphacite-diopside clinopyroxenethis paper
plagioclase and potassium feldsparmetapelite, igneousHolland & Powell (2003) Contrib Mineral Petrol 145 492-501
garnetmetapeliteWhite et al (2014) J Metamorph Geol 32 261-286
biotitemetapeliteWhite et al (2014) J Metamorph Geol 32 261-286
orthopyroxenemetapeliteWhite et al (2014) J Metamorph Geol 32 261-286
olivineHolland & Powell (2011) J Metamorph Geol 29 333-383
muscovitemetapelite, igneousthis paper
chloritemetapeliteWhite et al (2014) J Metamorph Geol 32 261-286
epidotemetapelite, igneousHolland & Powell (2011) J Metamorph Geol 29 333-383
ilmenite and hematitemetapeliteWhite et al (2000) J Metamorph Geol 18 497-511
spinel magnetitemetapeliteWhite et al (2002) J Metamorph Geol 20 41-55

Use for: equilibria in typical metabasite bulk compositions at < 20 kbar (or cautiously at < 30 kbar).

Known issues/warnings:

  • Subsolidus equilibria! Calculated stable phase relations in the blueschist and greenschist facies are very sensitive to some poorly known parameters, chiefly (I think) the standard enthalpies of formation of the amphibole end-members, which appear in three amphibole phases. To see the problem, compare calculations using ds62 and ds63. Although these two datasets are not meaningfully different in a statistical sense (ds63 was created in order to add some new end-members related to (?)peridotite equilibria), the stable assemblages look petrologically sensible with ds62, but not with ds63.
  • Note that there are two different cpx x-eos in this set, augitic clinopyroxene and jadeite-omphacite-diopside clinopyroxene. They should never be used together! There are notes on this included with the file downloads below.
  • Clinopyroxene appears to be too stable in amphibolites.
  • The clinoamphibole x-eos sometimes takes too much tetrahedral Al, resulting in < 6 Si p.f.u. on a 24-oxygen basis.
  • Are you aware of any other problems? Please let us know!

Full model details and benchmark calculations

Here we provide human-readable details of the metabasite-set HPx-eos, along with benchmark calculations to allow implementations to be tested. Contact us if anything remains unclear.

Download full HPx-eos details for phases: silicate melt, clinoamphibole, clinopyroxene (with tschermaks substitution; no M2-site order-disorder), clinopyroxene (no tschermaks substitution; full omphacitic order-disorder), orthopyroxene, garnet, olivine, feldspars, spinel/magnetite, ilmenite/hematite, epidote, biotite, muscovite, chlorite:

End-members from dataset version: 6.2 (Mon 6 Feb, 2012)

Benchmarks, generated with THERMOCALC 3.50. These files don’t necessarily represent key (or necessarily most stable) equilibria; they are just to check implementation of the x-eos. Contact us if you need specific additional calculations for comparison and are unable to produce these yourself. Download here:

Download THERMOCALC input files

If you’re new to THERMOCALC, please begin by reading the THERMOCALC section of the website, and download the files below as directed in the Get started guide.

Download THERMOCALC input files/information for the metabasite-set HPx-eos here (the current bundle is dated 13-12-2019):

  • Dataset 6.2 input file tc-ds62.txt (Mon 6 Feb, 2012).
  • Axfiles tc-mb47NCKFMASHTO.txt, formatted for THERMOCALC version 3.47, and tc-mb50NCKFMASHTO.txt, for version 3.50. These files replace tc-6axNCKFMASHTOm40.txt and 6axNCKFMASHTOm45.txt from the original web distribution, correcting a typo in the model for Ibar1 plagioclase in 6axNCKFMASHTOm45.txt.
  • Full descriptions of the x-eos, including definitions of mixing sites, end-members and compositional variables.
  • Samecoding information and a selection of starting guesses for compositional/order variables that might be suitable as a starting point for a calculation.

Information related to use with other software

In Perple_X: HPx-eos that were first published in the metabasite set are labelled “(G)”. The many x-eos that are shared by the metabasite and metapelite sets, and were first published in the metapelite set, are labelled “(W)”. Jeff Moyen’s spreadsheet gives more information.

Please contact us if you think there is other information we should include here.