Abstract
The system CaO-Al2O3-Na2O-MgO-SiO2-H2O is suitable for modelling phase equilibria and mineral parageneses for low-T metamorphism of basaltic rocks; univariant reactions marking the transitions between various sub-greenschist facies are identified and some have been determined experimentally. The introduction of Fe2O3 into a model of fixed FeO/MgO ratio creates continuous reactions for facies boundaries and discontinuous reactions for invariant points. The XFe3+ isopleths for epidote are plotted to illustrate the transition from the zeolite facies, through prehnite-pumpellyite to the prehnite-actinolite facies, and T-XFe3+ relations are established for both continuous and discontinuous reactions relating such facies transitions. An isobaric Al-Ca-Fe3+ plot from the chlorite projection can be applied to low-T metamorphic rocks where two or three Ca-Al silicates occur.-R.A.H.
Original language | English |
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Pages (from-to) | 321-333 |
Number of pages | 13 |
Journal | Mineralogical Magazine |
Volume | 49 |
Issue number | 3 |
DOIs | |
Publication status | Published - 1985 |
ASJC Scopus subject areas
- Geochemistry and Petrology