STAUROLITE+KYANITE-BEARING PSEUDOMORPHS AFTER ANDALUSITE (CAP DE CREUS, SPAIN)

International audienceMetapelitic rocks from Cap de Creus (Eastern Pyrenees, Spain) have developed andalusite ± cordieritebearingassemblages during the Variscan low-pressure high-temperature metamorphism. Andalusite crystalsare commonly transformed to very fine-grained assemblages containing staurolite and kyanite (± chloritoid)together with white micas and biotite. The hydrous character of the replacement minerals (pseudomorphinganhydrous andalusite) and the fact that transformation locally occurs along fractures, suggests that it wasenhanced by fluid circulation.Using calculated phase diagrams (pseudosections), the equilibration of the main andalusite-bearingassemblage is constrained at < 4 kbar and 550-600°C. Various types of phase diagrams are combined witha detailed analysis of the crystallisation sequence of the replacement minerals, in order to investigate theconditions of formation of the staurolite + kyanite(±chloritoid)-bearing pseudomorphs. Finally, it is discussedwhether the pseudomorphs reflect a “simple” retrograde alteration, a retrogression associated with apressure increase, or a prograde overprint during another (Pyrenean) orogenic cycl