Petrological investigation of dacitic domes, dome flows and pyroclastics related with dacitic domes in Erciyes stratovolcano

Erciyes (3917 m), one of the most important volcanoes of Central Anatolia, is a typical stratovolcano. The most important activities of Erciyes volcano varying from basaltic composition to rhyolitic compositions are dacitic-rhyodacitic dome emplacements and related young explosive products. In this study, 41 lava domes are identified and sampled around Erciyes main cone. Mineralogical, petrographical and geochemical features of domes and dome-related pyroclastic units were investigated and mineral chemistry studies were carried to understand the processes that are effective in the formation of volcanism. In addition, U/Th zircon mineral crystallization ages and (U-Th)/He explosion ages were obtained from domes and emplacement of domes in time-space has been revealed. According to the data obtained, age of the domes present two age ranges. Range 1, between 368-239 ka, called Pleistocene domes: Gökdağ Tepe (368 ± 27 ka), Üç Tepeler (342 ± 26 ka), Şeyharslanın Tepe (331 ± 17 ka), Ali Dağ (275 ± 17 ka), and Lifos Tepe (239 ± 12 ka). Range 2, Holocene domes: Yılanlı Dağ (11,8±1,1 ka), Perikartın Tepe (11,4±0,9 ka), Dikkartın Dağ (9,4±1,4 ka), and Karagüllü Tepe (7.2 ±0.7 ka). The common feature of the Holocene domes is that the volcanism begins with explosive activities and ends with dome emplacement. The youngest eruption in the Erciyes volcanism belongs to the Karagüllü Tepe dome where is situated to the north of Erciyes and it's explosion age is 7.2 ± 0.7 ka. This finding is the youngest age data obtained from Erciyes volcanism within the scope of this study when it is compared with the previous studies. According to the petrography studies mineral paragenesis of the rocks are determined and samples are generally consist of plagioclase, pyroxene and amphibole minerals. It is determined that Karagüllü Tepe dome is different from other domes by containing biotite minerals. Due to the mineralogical and textural features of minerals indicate that magma mixing processes are effective in the generation of volcanic rocks. According to the results of the major element geochemical analysis of the Erciyes products ranging from dacite to rhyolite belongs to the calc-alkaline character. It was seen that the fractional crystallization processes in the magma formed by the volcanic rocks. According to the trace element geochemical analysis, along with the fractional crystallization, crustal contamination processes effected magma too.