Metamorphism, magmatism, and exhumation history of the Tavşanlı Zone, NW Turkey: new petrological constraints

Authors : Şenel ÖZDAMAR, Gürsel SUNAL, Muhterem DEMİROĞLU, Cenk YALTIRAK, Mehmet Zeki BİLLOR, Stoyan GEORGIEV, Willis HAMES, İstvan DUNKL, Halil Can AYDIN

Pages : 269-293

View : 15 | Download : 6

Publication Date : 0000-00-00

Article Type : Research Paper

Abstract :The Tavşanlı Zone insert ignore into journalissuearticles values(TZ); is a high-pressure/low-temperature metamorphic belt representing subduction and exhumation between the Sakarya Zone and the Afyon-Bolkardağ Zone in western Anatolia. This paper provides new and precise geological data including whole-rock and mineral chemistry, phengite 40 Ar/ 39 Ar ages, zircon laser ablation ICP-MS U-Pb, and apatite insert ignore into journalissuearticles values(U-Th);/He thermochronological information for a region of the Sivrihisar metamorphic complex that has been less studied than other regions of the TZ. This region comprises Permo-Carboniferous metamorphic units, Eocene granodiorite and microgranodiorite, terrestrial clastics, and Holocene alluvium. The mineral assemblage of the granite-gneiss contains quartz, plagioclase, K-feldspar, microcline, muscovite, and rare biotite and garnet, while the blueschist comprises plagioclase, white mica, biotite, Na-amphibole, and garnet that are considered to represent greenschist and blueschist facies metamorphism, respectively. We estimate the peak metamorphic conditions for schists of the Permo-Carboniferous metamorphics and associated rocks as T = 303-484 °C and P >=10 kbar. This high-pressure event occurred at ca. 83 Ma, indicated by a well-defined 40 Ar/ 39 Ar plateau age for phengite. Laser ablation ICP MS U-Pb analyses of euhedral or subeuhedral magmatic zircons from previously unknown microgranodiorite, intruding the metamorphic rocks, yield an Eocene insert ignore into journalissuearticles values(50 Ma); age. The new results are interpreted to indicate that lithospheric collision and northward subduction beneath the Sakarya Zone occurred between 83 and 50 Ma. Apatite crystals separated from microgranodiorite yield insert ignore into journalissuearticles values(U-Th);/He ages consistent with cooling of the Tavşanlı Zone to ~65 °C by ~38 Ma.
Keywords : 40 Ar 39 Ar, zircon ICP MS U Pb, apatite U Th, He, Tavşanlı Zone, Neo Tethys, Gondwanaland