Geology mineralogy and origin of kaolin deposits occurring around Ahirözü (Mihaliççık-Eskişehir)

Tezin Türü: Doktora

Tezin Yürütüldüğü Kurum: Orta Doğu Teknik Üniversitesi, Mühendislik Fakültesi, Jeoloji Mühendisliği Bölümü, Türkiye

Tezin Onay Tarihi: 2018




Hydrothermally originated Ahırözü kaolin deposits were developed within the contact of granite-serpentinite rocks in Ahırözü-Hamidiye villages, Mihalıççık, Eskişehir-Turkey. The purpose of this research is to investigate the mineralogy, geology and genesis of Ahırözü kaolin deposits by using petrographical analyses, chemical analyses (ICP-MS and ICP-ES), X-ray powder diffraction (XRD) method, scanning electron microscopy with an energy dispersive X-ray spectroscopy (SEM-EDX) analyses, stable isotope analyses (oxyhen/hydrogen) and fluid inclusion analyses. Experimental studies of CO2-H2O-serpentine based reactions were performed to understand the formation mechanism of listwanites occurred in the study area. Experiments were conducted at 25 ⁰C and 80 ⁰C with P (CO2) = 110 to 130 bar. The argillic alteration zone (Zone A) includes kaolinite, halloysite, natroalunite and accessory pyrite. The presence of K-Feldspar and graphic texture in the Zone A indicates that the protolith rock has a granitic origin. The propylitic alteration zone (Zone B) is mainly characterized by chlorite-smectite-illite and epidote. Zone C represents silica sinter formation. According to the fluid inclusion analyses, it has been obtained that the homogenization temperature (Th°C) varies between 126⁰C and 365⁰C and wt. % NaCl values change between 3.9- 6.2. Thus, it is indicated that these kaolin deposits have an epithermal hydrothermal origin. The rocks in the kaolin deposit are depleted in Rb and Pb while being enriched in Cs and U elements. Regarding to the stable isotope analyses, δD varies between -80.86 and -88.81 whereas δ18O values ranges from 5.03 to 8.73 which indicating the contribution of magmatic waters in the hydrothermal system.