International Geological Journal - Official Journal of the Carpathian-Balkan Geological Association

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

Pages: 197 - 210

Authors: OMER BOZKAYA, HUSEYIN YALCIN, ZEYNEL BASIBUYUK, OLCAY OZFIRAT, HUSEYIN YILMAZ

Abstract: The Southeast Anatolian Metamorphic Complex comprises three structural units, the Keban, Malatya and Pütürge-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, 2M1 white K-mica, 1M 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 2M1 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 Pütürge Metamorphics (Precambrian-Permian) comprise metamorphic lithologies of pre-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 biotite, reflect post-metamorphic-peak cooling assemblages. Low-grade parts of this unit are made up of calcite, dolomite, albite, phyllosilicates (IIb chlorite, 2M1 muscovite and 1M biotite, C-S), reflecting greenschist-facies metamorphic conditions. Lithological and mineralogical characteristics of the Southeast Anatolian Metamorphic Complex imply the following: the Keban Metamorphics are similar to the Eastern Taurus Autochthon (Geyikdağı 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. Aladağ Unit). The Pütürge 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.

Keywords: X-ray powder diffraction, low-grade metamorphism, petrography, crystallinity, polytype, b0 value, organic-matter reflectance, phyllosilicate

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