Cooling and deformation history of the Çataldağ Metamorphic Core Complex (NW Turkey)

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Özet

The Çataldağ Metamorphic Core Complex (ÇMCC) consists of the Latest Eocene-Early Oligocene (34–32 Ma) Turfaldag gneiss-migmatite complex (TGMC) and an Early Miocene (21 Ma) Çataldağ synkinematic pluton (ÇSP) which were exhumed as a dome-shaped core complex in the footwall of the Çataldağ Detachment Fault Zone (ÇDFZ) in the Early Miocene. Microstructural features of the Çataldağ Metamorphic Core Complex (ÇMCC) and a two-feldspar geothermometry were studied to understand the cooling and deformation mechanisms. Microtectonic analyses of the TGMC and ÇSP show that the quartz, feldspar, and mica minerals underwent continuous deformation from ductile to brittle conditions during cooling of the ÇMCC. Two main deformation zones were determined according to temperature and strain intensity: a ductile deformation zone (DZ) within the central zones of the TGMC and ÇSP, and a mylonitic zone (MZ) within the peripheral zones of the TGMC and ÇSP (close to the ÇDFZ). Within the ductile zone, K-feldspar displays microcline twinning, myrmekite along the K-feldspar megacryst and flame-shaped perthite, and quartz displays chessboard extinction, grain boundary migration, and sub-grain rotation recrystallisation. These microstructures indicate that deformation temperature reached about 600 °C. Under high strain intensity along the ÇDFZ, the DZ microstructures turn to MZ microstructures. In the MZ, protomylonitic gneiss and mylonitic schists show distinct foliation and their K-feldspar and micas display C-S structures. The feldspars show bulging recrystallisation, a feldspar-fish structure, and domino-type microfractures, while the quartz displays ribbon structures, indicating ductile-to-brittle deformation with temperatures ranging from 500 °C to <250 °C. Two-feldspar geothermometry yields deformation temperatures in the DZ of 501–588 °C (an average of 544 °C for the ÇSP and an average of 517 °C for the TGMC) consistent with the temperature estimated by the microstructural analysis. The mylonitic zone has lower deformation temperature values of 430–557 °C (an average of 484 °C for ÇSP and an average of 436 °C for TGMC). Thermochronology data display TGMC was cooled slowly (<50 °C/my) throughout the Eo-Oligocene and rapidly (>500 °C/my) along the ÇDFZ in the Early Miocene (21 Ma). The shear zone-controlled ÇSP was emplaced into shallow levels of the Anatolian extending crust, deformed progressively (ductile-to-brittle) along the ÇDFZ, and cooled rapidly (>500 °C/my) in the Early Miocene (21 Ma). Together, the microstructure, two-feldspar geothermometry and thermochronology data indicate that the TGMC and ÇSP, which were emplaced into different crustal levels and in different periods, suffered continuous ductile-to-brittle deformation and were exhumed together along the ÇDFZ during the Early Miocene under the N-S extensional regime in western Anatolia.

Orijinal dilİngilizce
Sayfa (başlangıç-bitiş)279-291
Sayfa sayısı13
DergiJournal of Asian Earth Sciences
Hacim172
DOI'lar
Yayın durumuYayınlandı - 1 Nis 2019

Bibliyografik not

Publisher Copyright:
© 2018 Elsevier Ltd

Finansman

This study was supported by research grants from the Scientific & Technical Research Council of Turkey ( TUBITAK-CAYDAG-109Y082 ) and Istanbul Technical University (BAP projects no 36010 and 40647). We are grateful to Alp Unal for helpful participation in the field. We would like to thank Gursel Sunal for his constructive comments and useful suggestions. Many thanks to Olivier Vanderhaeghe and an anonymous reviewer for their constructive contributions that helped improving and clarifying the original manuscript.

FinansörlerFinansör numarası
Scientific & Technical Research Council of TurkeyTUBITAK-CAYDAG-109Y082
Istanbul Teknik Üniversitesi36010, 40647

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