Coronitic rock volumes preserve the structural and chemical memory of geological events that are commonly not preserved in intermediate to high strain rock volumes (Lardeaux and Spalla, 1991; Spalla et al. 2004; Holyoke and Tullis, 2006). The new metamorphic phases generally grow by developing corona textures rather than new planar fabrics, allowing the preservation of the composition of old microdomains. These features allow to relate reaction products to their reactants and investigate the relative timing of reactions with respect to the chemical and mechanical changes in individual microdomains as well in the surrounding rocks.

Corona textures may allow the identification of metamorphic reactions (Vernon and Clarke, 2008) and subsequently, when thermobarometry and geochronology is undertaken, the reconstruction of the P-T-t paths.

In this contribution a microstructural analysis of a pre-Alpine (Permian?) metagranite is presented; the patchy distribution of high pressure – low temperature metamorphism allowed partial preservation of the microstructures and chemical compositions of the primary igneous phases, along with preservation of prograde to retrograde assemblages.

The geometry, mineral composition and chemistry patterns of igneous microdomains are investigated using optical microscopy, X-rays compositional maps, chemical analyses and overall image analysis, in order to detail the microstructural evolution and to reconstruct the relative chronology of the reactions.