Metamorphic evolution of the Karakaya Complex in northern Turkey based on phyllosilicate mineralogy


MINERALOGY AND PETROLOGY, vol.109, no.2, pp.201-215, 2015 (SCI-Expanded) identifier identifier

  • Publication Type: Article / Article
  • Volume: 109 Issue: 2
  • Publication Date: 2015
  • Doi Number: 10.1007/s00710-014-0364-0
  • Journal Indexes: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Page Numbers: pp.201-215
  • Middle East Technical University Affiliated: Yes


The Triassic Karakaya Complex (KC) of the Sakarya Composite Terrane in northern Turkey is traditionally subdivided into two units. The Lower Karakaya Complex (LKC) consists of a tectonic m,lange with blocks of metabasic rocks, metacarbonates, meta-arenites and metapelites that have been affected by high pressure/low temperature metamorphism. It is followed by a low pressure/low temperature metamorphic overprint; the latter is the only metamorphic event in some tectonic slivers of the LKC. The Upper Karakaya Complex (UKC) units are primarily composed of diagenetic to low-grade metamorphic rocks, comprising Late Permian and Triassic cherts and blocks of OIB-type volcanic rocks interfingering with Anisian limestones. LKC slide-blocks of variable sizes are frequently observed within the UKC. Phyllosilicates of LKC and UKC were examined for their abundance, crystallinity, polytype and b cell dimension. Trioctahedral chamositic chlorites have IIb polytype and phengites 2 M (1) polytypes in the LKC units and 2 M (1) + 1 M + 1M (d) polytypes of phengitic dioctahedral illites in the UKC units. Kubler index data correspond to the low anchizone and epizone for the LKC units, and to the high diagenesis-low anchizone, and in part to the epizone for the UKC units. The b values of illites are consistent with a high-pressure facies series for the LKC, but only intermediate-pressure facies for the UKC. According to textural features, mineral paragenesis, clay transformations, index minerals, and b values, the lower-middle parts of the LKC represent an accretional tectonic setting, whereas the UKC units reflect pressure temperature conditions of an extensional basin affected by high heat flow.