The origin and geochemical characteristics of rutile in eluvial and fluvial-alluvial placers and quartz veins of the Menderes Massif from the Neoproterozoic Pan-African Belt, Western Turkey.

Rutile occur in important amounts within Quaternary detrital sediments, and quartz veins which cut down the Paleozoic aged Eşme formation in the Menderes Massif on the Neoproterozoic Pan-Afrikan Belt in the west of Turkey. As a result of erosion, transport and accumulation of rutile-bearing quartz veins in the mica schists of the Eşme formation outcropped between Eşme (Uşak) and Kula (Manisa), the placer rutile occurrences occur in terraces, fluvial-alluvial and eluvial deposits. This study investigates the element content of rutile, oxygen isotope ratios of rutile and quartz, and formation temperature of rutile related to titanium source rock. Field observations show that rutiles are located in quartz veins that cut the schists. After these veins were fragmented and eroded, blocks of quartz with rutile and rutile grains are transported into clastic sediments in slope debris (eluvial), terraces and recent fluvial-alluvial deposits. Whereas quartz, rutile, ilmenite, and albite are found in the paragenesis of the rutile-bearing quartz vein fragments, the placers forming the terraces and current fluvial-alluvial deposits contain quartz, albite, muscovite, orthoclase, kaolinite, rutile, dravite, ilmenite, and zircon. The rutile grains in the examined placers and quartz vein fragments have grain sizes ranging from mm fractions to 5–6 cm. The major oxide compositions of the rutile grains have average values of 94 wt.% TiO 2 , 1.5 wt.% Fe 2 O 3 , 0.5 wt.% SiO 2 , and 0.3 wt.% Al 2 O 3 . The rutile samples have average values Nb of 1424 ppm, V of 980 ppm, W of 192 ppm, Ta of 94 ppm, and Zr of 73 ppm. The rutiles in the study area are defined as iron-rich rutile “nigrine” due to high iron content. Quartz veins are host rocks of rutile grains in the terrace and fluvial-aluvial sediments. The rutile-bearing quartz veins may be sourced from the Lower-Middle Miocene aged granites which are intruded the rocks in the Menderes Massif. Based on the analysis results of the methods of Zr thermometer from Zr values containing rutile and quartz-rutile geothermometer from oxygen isotope results (13.5‰ and 6‰) of quartz and rutile samples, the formation temperature of the rutile-bearing quartz veins were found to be at temperatures of 537 °C and 561 °C, respectively. These temperatures indicate that the rutile-bearing quartz veins may be in a temperature range between pegmatitic and/or hydrothermal stages. [ABSTRACT FROM AUTHOR]