Geological, mineralogical and geochemical features of placer rutile deposits in the Menderes Massif (Eşme-Kula-Gördes regions)

This study investigates the mineralogical and geochemical properties and origin research of placer rutile formations in the Köseler village of Gördes District (Manisa), and in the region between the Dervişli village (Eşme-Uşak) and the Eroğlu village (Kula-Manisa). The Köseler area is mainly composed of gneiss and migmatites of Paleozoic aged, which are cut by a granite unit of upper Oligocene-aged. A Cretaceous-aged ophiolite unit belonging to the Izmir-Ankara zone, is allochthonously located on the granite unit and produces relatively small outcrops. The Quaternary alluvial accumulations represent the youngest unit in the study area. Placer rutile enrichments are found in the alluviums of the stream in this area, as well as in the small terraces and profiles nearby. The mineralogical investigations of the Köseler area revealed the presence of quartz, muscovite, kyanite, garnet, rutile, and ilmenite minerals. The oldest unit in the study area between Dervişli-Eroğlu villages is the Paleozoic Eşme Formation. The lower part of this formation consists of paragneiss, while the upper part contains fine-grained gneiss and schists. The Pliocene aged Ahmetler Formation lies unconformably over the Eşme Formation. Quaternary aged alluvial deposits consisting of gravel, sand, silt, clay and stream alluviums unconformably overlie the Ahmetler Formation. Terrace deposits and stream beds within the Dervişli-Eroğlu area contain placer rutile enrichments, along with alluviums. The mineralogical investigation of the Dervişli-Eroğlu rutile field revealed the presence of several minerals, including quartz, albite, biotite, muscovite, orthoclase, amphibolite, garnet, kaolin, rutile, tourmaline, and ilmenite, in rutile placers. Ilmenite was detected in rutile mineral through ore microscopy studies on polished sections of rutile samples collected from Köseler and Dervişli-Eroğlu fields. EPMA analysis on the same samples also yielded similar results. The rutile samples from Köseler field showed average major oxide values of 76.49% TiO2, 22.12% Fe2O3, 0.98% SiO2, 0.39% Al2O3, 0.12% Cr2O3 and 0.24% MgO. Similarly, the major oxide values of Dervişli-Eroğlu field rutile samples have an average of 93.99% TiO2, 1.56% Fe2O3, 0.56% SiO2, 0.28% Al2O3, 0.06% Cr2O3 and 0.03% MgO. The rutile samples in the Köseler field have an average content of 643.42 ppm Nb, 1145.42 ppm V, 410 ppm Cr, 66.14 ppm W, 48.57 ppm Ta, 71.28 ppm Zr, 37.71 ppm Sn and 3.11 ppm. The Dervişli-Eroğlu field has an average of 1423.35 ppm Nb, 979.37 ppm V, 423.31 ppm Cr, 191.26 ppm W, 93.72 ppm Ta, 72.81 ppm Zr, 65.37 ppm Sn, and 3.63 ppm Hf values. The oxygen isotope analysis results for rutile and quartz samples from the Köseler field are 1.2‰ and -1.9‰, respectively. For the Dervişli-Eroğlu field, the results are 6.1‰ and 13.4‰, respectively. The zircon geothermometer analyses within rutile indicate that the Köseler field was formed at an average temperature of between 534°C and 538°C, while the Dervişli-Eroğlu field was formed at an average temperature of between 535°C and 538°C. The quartz-rutile geothermometer studies conducted on the oxygen isotope values of rutile and quartz samples from the Köseler field yielded inaccurate results. In contrast, the average temperature value obtained from the quartz-rutile geothermometer studies conducted on the oxygen isotope values of the rutile and quartz samples from the Dervişli-Eroğlu field was 534°C. The trace element results of the rutile samples from the Köseler and Dervişli-Eroğlu fields indicate that the rutiles originate from hydrothermal quartz veins that cut through the metamorphic rocks in the fields. Subsequently, they are transported to alluvial and eluvial accumulation areas where they become concentrated. The results of the Zr in rutile thermometer and quartz-rutile geothermometer studies also indicate a hydrothermal origin.