The island of Sifnos in the Aegean Sea , Cyclades ( Greece ) is well known for its spectacular and well preserved blueschists and eclogites. The best preserved assemblages occur in structurally high tectonic slices that outcrop in the north of the island. These slices occur in the upper-plate of a major detachment fault. The occurrence of eclogites and blueschist rocks overlying greenschists is a matter of debate, and contrasting interpretations have been proposed to explain the anomalous nappe stack.
A different interpretation implies that blueschists and greenschists derived from different structural levels, being juxtaposed during the exhumation history. Several exhumation mechanisms have been suggested, including extensional tectonics (Lister et al., 1984; Avigad, 1993), thrust tectonics (Lister & Raouzaios, 1996) and exhumation via an extrusion wedge (Ring & Layer, 2003). A detailed reconstruction of the decompressional P-T path may give information essential to discriminate among these different and contrasting models.