High-pressure rocks of Samos, Greece

Abstract

Summary The metamorphic complex of Samos is composed mainly of marbles and phyllites, typically with intercalations of serpentinites, meta-gabbros, blueschists, and greenschists. The meta-gabbros show typical flaser-structures, but contain frequent textural relics of the igneous protolith as well as relict clinopyroxene and brown hornblende. Primary plagioclase is totally replaced by albite, epidote or zoisite. Critical mineral assemblages of the Alpidic metamorphism are: albite + epidote + chlorite + glaucophane ± barroisite + sphene, albite + epidote + zoisite + tremolite + muscovite + sphene, albite + epidote + chlorite + tremolite ± barroisite ± muscovite ± calcite ± sphene. Associated glaucophanites show the following critical assemblages (+ sphene ± rutile): garnet + glaucophane + epidote ± barroisite + chlorite + muscovite ± paragonite, glaucophane + epidote + chlorite + muscovite + albite ± quartz. The major and trace element chemistry confirms that the metabasites are derived from abyssal tholeiites and related gabbros. The metapelites of Samos frequently contain chloritoid which, in the eastern part of the island, may be accompanied by kyanite, and rarely by Mg-carpholite. Meta-bauxites in eastern Samos contain diaspore, in western Samos diaspore + corundum (Mposkos 1978). At the peak of metamorphism temperatures may have reached about 420° and 470°C in east and in west Samos respectively, assuming elevated pressures of about 8 kbar.