Quantitative X-ray Maps Analaysis of Composition and Microstructure of Permian High-Temperature Relicts in Acidic Rocks from the Sesia-Lanzo Zone Eclogitic Continental Crust, Western Alps

Three samples of meta-acidic rocks with pre-Alpine metamorphic relicts from the Sesia-Lanzo Zone eclogitic continental crust were investigated using stepwise controlled elemental maps by means Quantitative X-ray Maps Analyzer (Q-XRMA). Samples chosen aim analysing reacting zones along boundaries between and Alpine mineral phases, which developed in low chemically reactive systems. The quantitative data treatment images was based on a former multivariate statistical analytical stage followed sequential phase sub-phase classification permitted to isolate quantitatively investigate local paragenetic equilibria. parageneses thus observed interpreted as related or magmatic stages well re-equilibrations. On basis electron microprobe analysis, specific compositional ranges defined micro-domains relict new In this way calibrated obtained used contour different types adjacent solid solution phases. allowed perform geothermobarometry statistically meaningful reliable dataset. general, temperatures cluster at 600–700 °C 450–550 °C, lower referred retrograde re-equilibration. all cases described, overprinted an assemblage. Pressure-temperature estimates averagely range 420 550 12 16.5 kbar. PT constraints better define scenario western Austroalpine sectors, understand influence inheritance forthcoming tectonic evolution.