Origin and evolution of the Southeast Anatolian Metamorphic Complex (Turkey)

Abstract

The Southeast Anatolian Metamorphic Complex comprises three structural units, the Keban, Malatya and Puturge-Bitlis Metamorphics. Of these, the Keban Metamorphics (Carboniferous-Triassic) mainly comprise metamorphosed limestones/marbles and phyllites, consisting mainly of calcite, dolomite, quartz, albite, phyllosilicates (kaolinite, 2M(1), white K-mica, IM biotite, IIb chlorite, C-S, C-V and I-S) and scarce tremolite/actinolite and biotite, which were metamorphosed under sub-greenschist- to greenschist-facies conditions. The Malatya Metamorphics (Carboniferous-Triassic) comprise mainly metacarbonate rocks and metapelites - made up of calcite, quartz, albite, phyllosilicates (anchizonal-epizonal 2M, white K-mica and paragonite, IIb chlorite, dickite, C-V, C-S, I-S), chloritoid and goethite - that underwent a sub-greenschist-facies metamorphic event. The Puturge Metamorphics (Precambrian-Permian) comprise metamorphic lithologies of pie-Devonian high-grade (augen gneiss, amphibolite, mica schist/gneiss, granitic gneiss) and post-Carboniferous low-grade rocks (calc-schist/ marble and schist). The high-grade parts of this metamorphic unit display a Barrovian-type prograde metamorphism at amphibolite facies. Retrograde mineral occurrences, such as chlorite, C-V and C-S from garnet and biotile, reflect post-metamorphic-peak cooling assemblages. Low-grade parts of this unit are made up of calcite, dolomite, albite, phyllosilicates (IIb chlorite, 2M, muscovite and IM biotite, C-S), reflecting greenschist-facies metamorphic conditions. Lithological and mineralogical characteristics of the Southeast Anatolian Metamorphic Complex imply the following: the Xeban Metamorphics are similar to the Eastern Taurus Autochthon (Geyikdagi Unit) and apparently originated from that unit. In spite of their similar age ranges, the Malatya Metamorphics are quite different from the Keban Metamorphics and were probably derived from northern allochthonous Tauride units (e.g. Aladag Unit). The Puturge Metamorphics originated from a southern source (i.e. the Arabian Platform), and horizons of similar age differ from those of the Keban and Malatya Metamorphics.