Mi̇neralogical, petrographical, and geochemi̇cal investigation of bi̇lezi̇k tepe (Göre, Nevşehi̇r) and its surroundings

This study aims to reveal the mineralogical-petrographic and geochemical properties of the bentonites recently discovered in the Göre (Nevşehir) region, located in the Central Anatolian Volcanic Province (OAVP), and also to determine the alteration minerals. In this regard, optical and electron microscopes, X-ray diffraction, X-ray fluorescence spectrometry, and inductively coupled plasma-mass spectrometry examinations were carried out. In the study area, Aşıkidağ Andesite, Kavak Ignimbrite, and Kumtepe Ignimbrite units are generally observed. The alteration, which mostly affects pyroclastic (ignimbrite) and partly lava products, has resulted in gray-yellowish-whitish siliceous and grayish-green clay mineral formations. Altered samples mainly include silica minerals (quartz, cristobalite, opal-CT), clay (smectite, montmorillonite, ± illite), biotite ± pyroxene mineral as a ferromagnesian mineral, and feldspar group minerals (K-feldspar and plagioclase). Is the based on 11 oxygen atoms: (Na, Ca, K)0.3-0.4(Al, Fe, Mg)2 (Si4O10) (OH)2 It was determined as montmorillonite dioctahedral Ca-smectite. Cation exchange capacity (CEC) values are in the range of 0.190-0.761 meq/g and increase in direct proportion to the smectite contents. According to major and trace element compositions, low-medium grade alteration product ignimbrites and high-grade alteration product bentonites are derived from alkaline magma with trachy-andesitic (intermediate) composition. Keywords: Bentonites, Smectite, Cation Exchange Capacity (CEC).