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In this study, we investigate the geochronological, geochemical and isotopic characteristics of two travertine sites surrounded by Quaternary eruption centres in central Anatolia with ample palaeo-eruption records. High-resolution carbonate precipitation records, revealed by U-Th dating, are clustered around 5–35, 60–100 and 120–170 ka and are well correlated with the dataset on eruptions as well as the position of fractures related to the volcanic centres. Syn-eruptive carbonate precipitation seems to occur due to the circulation of CO2-rich fluids along the extensional fracture systems aligned tangentially to the related volcanic conduit and, therefore, the study of this system could be an alternative technique for the reconstruction of palaeo-eruptions. δ18O values of the studied travertines are within the range of meteogene fluids. Oxygen isotope compositions at around 130 ka match well with Glacial Termination II that is also recorded by climate proxies in various cave and benthic deposits throughout the world. It is likely that the studied carbonates were precipitated under similar fluid circulation conditions which are represented by a high rate of dilatation followed by a meteoric water influx into the extensional fractures.  相似文献   
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This study focuses on the nature of giant micas occurring at the contact between the ?zvatan (foid-bearing) syenites and the metamorphic basement in Central Anatolia. The studied micas are dark greenish-black in color and crystallized within vein shape like bodies as a narrow lens. The origin and processes responsible for the formation of these independent crystals of the giant micas were investigated by mineralogical, petrographical and geochemical analyses with the use of Confocal Raman Spectroscopy (CRS), Fourier Transform Infrared (FTIR) Spectroscopy, X-Ray Diffraction (XRD), Polarized Energy Dispersive X-Ray Fluorescence Spectrometer (PED-XRF) and Electron Probe Micro Analysis (EPMA). According to XRD, CRS, FTIR and EPMA data, the giant micas are phlogopite. EPMA results reveal that studied mica minerals represent the products of re-equilibrated primary mica characterized by high MgO and FeO and low Al2O3 and TiO2 contents. The trace element concentrations of the giant micas display similar patterns with the upper crust. The giant micas are crystallized within small cubicles from an alkaline magma and their composition is possibly modified by a mixing event between the crust- and mantle-derived magmas and contaminated at varying extent by the basement metamorphic rocks.  相似文献   
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