Primary Findings of Alteration Minerals in the Perlite Deposits in Yukarıemirler (Ankara-Central Anatolia): Characterization of Hydrothermal Fluid

Abstract

Çubuk site is located in Ankara (Turkey) and is known for its agate which is a semi-precious mineral and is found extensively in the region. In addition to the agate minerals, the perlite quarries in the region are also operated as industrial raw materials. Perlites are products of the Middle-Miocene aged Susuz volcanic, containing rhyolite, dacite, tuff, and ignimbrite. A perlite quarry extends approximately SW-NE that is currently open pit operated for perlite raw material is located between Kuyumcu and Yukarıemirler villages. A clay formation by the effect of hydrothermal solutions was detected around a fault in the NW-SE direction in the quarry. Systematic sampling was made from the fault, and it was aimed at the characterization of clay minerals and detecting changing alteration levels according to the varying distance. The mineralogical-petrographical studies of the perlite reveal that perlitic texture "onion-skin like fractures" is the main characteristic texture and is observed in all of the studied samples. Euhedral feldspar and anhedral quartz minerals were observed in some thinsection. In addition, argillization and iron-oxidation were detected in the perlite samples. In the XRD analysis; Smectite and quartz minerals are enriched on the fault zone samples but smectite minerals are increased away from the fault. Feldspar mineral increases as further away from the fault zone. All these preliminary mineralogical and petrological information provide that the hydrothermal solution composition, which causes alteration in the quarry, was an alkaline character.