Partial melting of common metasedimentary rocks: A mass balance approach
✍ Scribed by N. D. MacRae; H. W. Nesbitt
- Publisher
- Springer
- Year
- 1980
- Tongue
- English
- Weight
- 505 KB
- Volume
- 75
- Category
- Article
- ISSN
- 0010-7999
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✦ Synopsis
Materials balance calculations are presented to document the progressive bulk chemical changes in metagreywacke and metapelite with separation of increments of granite of minimum melt composition. During partial melting, enrichment of Ee relative to Mg in granite and strong absorption of water leave residual rocks with increasing proportions of such Mg-rich phases as cordierite and progressively dehydrated. Extraction of most granitic compositions from metapelites results in increasing the A1 value of residua, while extraction of an alkali granite melt from metagreywacke is necessary to change the A1 values in their residua (from peraluminous to sub-or metaluruinous). Under essentially constant temperature conditions, complex isograds may develop locally reflecting the bulk chemical changes produced by melt removal. Natural amphibolite/granulite facies rocks from three locations in Canada are compared with the calulated trends.