Partial melting and P-T-t evolution of LP/HT metamorphic terranes: An example from the Svecofennian K-feldspar-poor leucosome migmatite belt, Southern Finland

H. Mouri, K. Korsman

Research output: Contribution to journalArticlepeer-review

2 Citations (Scopus)

Abstract

The migmatites with Kfs-poor leucosomes from the Svecofennian domain of southern Finland are characterized by a suite of anastomosing leucosome veins and patches characterized by low and varying abundance of K-feldspar with or without cordierite. These leucosomes are generated by in situ melting reactions at different P-T-aH2O conditions. Microtextural analysis in conjunction with THERMOCALC calculations and geothermobarometry show that these rocks were metamorphosed under granulite facies conditions at 700-750°C, 4-5 kbar and aH2O = 0.4-0.7. The formation of cordierite coronas around garnet and the late crystallization of andalusite suggest that the final stage of the P-T history was characterized by decompression and cooling to within the andalusite stability field, estimated at 500-650°C and 3-4 kbar. U-Pb and Sm-Nd conventional analyses of monazite and garnet, respectively, from different parts of these migmatites (mesosomes and leucosomes) indicate that, within error limits, all leucosomes were formed at about 1878 Ma during a single tectonometamorphic event. Since there is no evidence of an earlier high-grade metamorphic event in this area, it is assumed that this is the approximate age of peak metamorphism and partial melting.

Original languageEnglish
Pages (from-to)239-253
Number of pages15
JournalGeological Society Special Publication
Volume168
DOIs
Publication statusPublished - 2000
Externally publishedYes

ASJC Scopus subject areas

  • Water Science and Technology
  • Ocean Engineering
  • Geology

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