Mineralogical and geochemical characterization of can volcanics and releated kaolin deposits, Canakkale, Turkey

The Saribeyli - Siǧirli and Bodurlar kaolin deposits (Çanakkale) are hosted by andesitic tuffs of the Oligocene volcanic rocks. Çan volcanis are classified as andesite, basalticandesite and basaltic-trachy andesite and tuffs can be classified as andesite and rhyolite. Saribeyli-Siǧirli kaolin deposit exposes the following mineral zonations from the fault zone to the outer; i) quartz, ii) alunite ±quartz ±kaolinite ±dickite, iii) kaolinite ±dickite ±alunite ±quartz and iv) kaolinite +illite +feldspar, respectively. Bodurlu kaolin deposit exposes the following mineral zonations from the fault zone to the outer; i) quartz ±Feoxides ±alunite ±jarosite and ii) kaolinite ±halloysite ±illite ±quartz ±feldspar, respectively. The N30°W trending two faults passes through the north and south boundaries of kaolin quarry and four quarries have been operating inside the small scale graben. Fault zones pass through inside the Bodurlu quarry exhibit a group of six parallel fracture systems rather than single fault zone and kaolinization occurred between and vicinity of these fracture systems. Based on FE-SEM studies, micromorphologic features of kaolinite crystals show that kaolinite occurs as hexagonal blocky and book-shaped kaolinite which forms as ordered and disordered crystals. Halloysite habits are parallel and randomly non-parallel sticks. The δ³⁴S values of Saribeyli-Siǧirli deposits range from +4.1 to +2.4 ‰ and these values reflect its formation from magmatic-hydrothermal derived sulfur source. The δ¹⁸O and δD values in these deposits range from + 6.7 to + 12.7 ‰ and from - 61 to - 97 ‰, respectively, which are very close the line of primitive magmatic water. Isotopes data suggest that original geothermal waters were the mixture of magmatic water and meteoric waters. Oand H-isotopic values of the Bodurlu kaolin deposit are between δ¹⁸O +14.5/+17 ‰ and for δD -90/-99 ‰, which data reflect genesis of supergene origin and enriched regarding of δ¹⁸O values. According to mineralogical, geochemical and S-O-H data, these deposits were occurred by the ascending acidic geothermal waters through fault zones in the shallow epithermal systems, which are rich in kaolinite minerals. These steam-heated environments including hot-water outlets, H₂S enriched vapor and groundwater mixed in the vadose zone. These hypogene origin H₂SO₄ rich geothermal fluids cooled and oxidized when they mixed with cold groundwater when they reached to the surface through fault systems.