Akademik Veri Yönetim Sistemi
ACTA PETROLOGICA SINICA, cilt.37, sa.8, ss.2339-2363, 2021 (SCI-Expanded)
In the middle part of the Tethys metallogenic domain, the western section of Turkey concentrates porphyry-type deposits associated with three primary tectonic settings : subduction, collisiona-post-collision, and extension. Many studies have been performed on the petrogenesis and tectonic setting of porphyry deposits in the western section of Turkey. However, the current research is still in its infancy. Little systematic work has been done on the nature of the mineralized magma source, the content of ore elements-volatile elements , and the evolution of ore materials in porphyry deposits under different tectonic settings. It is crucial to understand the crustal thickness, the tectonic model, degree of crust-mantle interaction, and the evolution of ore materials during the formation of porphyry deposits during the subduction of the New Tethyan Ocean and the collisional-post-collisional-extension process of the Eurasian-Tauride-Anatolide plate since the Late Cretaceous in the middle section of Tethyan domain. In this study, zircon trace elements and apatite major elements were studied in five porphyry deposits from three metallogenic belts ( Tavpnli belt, Biga Peninsula metallogenic belt, and Afyon-Konya belt) in the western part of Turkey, to define zircon trace element characteristics, crystallizing temperature-oxygen fugacity conditions and volatile-component concentrations in the melts during the formation of porphyry deposits in different tectonic environments, and then to constrain the evolving processes of ore materials and to decipher the deep-crustal processes during the formation of porphyry systems during continental collision, subsequent post-collisional and extensional environments in the Tethyan domain. Zircon trace elements show that most igneous rocks from Cenozoic porphyry deposits in western Turkey show the features of high water content and high oxygen fugacity, with similar chondrite-normalized zircon REE patterns, and the mafic mineral enclaves present higher total rare-earth contents than the contemporaneous rocks; most zircons have Eu-N/Eu-N* from 0.4 to 0. 7, and zircon grains related to the porphyry Mo and porphyry Mo-Cu are more influenced by fractional crystallization plagioclase in the magma chamber; Ti-in-zircon thermometer estimates the crystallizing temperature of igneous rocks, ranging from 650 degrees C to 900 degrees C , with decreasing crystallization temperature from porphyry Au, to porphyritic Cu-Mo/Mo-Cu, then to porphyritic Mo deposits. The composition of zircon trace elements ( Yb/Gd and Hf/Y-Th/U) suggests the the features of trace elements in zircon are mainly controlled by fractional crystallization of hornblende +/- titanite +/- apatite; zircon oxygen fugacity Ce4+/Ce3+ ratio shows a decreasing ( porphyry Cu-Mo to porphyry Mo) and then increasing (porphyry Mo-Cu to porphyry Au) trend from Eocene to Miocene. Most of the Cenozoic porphyry deposits and their coeval magmatism in western Turkey exhibit " normal" volatile-element contents : EoceneOligocene porphyry Cu-Mo and Mo deposits have relatively high F and low Cl contents in the melt.In contrast, porphyry Mo-Cu and porphyry Au deposits formed in the Miocene extensional environments generally have high magmatic Cl contents.