Mineralogy, geochemistry and genesis of the Taşoluk kaolinite deposits in pre-Early Cambrian metamorphites and Neogene volcanites of Afyonkarahisar, Turkey

Abstract

Editor: John Adams)AB ST R ACT : The Tas°oluk kaolinite deposits of Afyonkarahisar (western Anatolia) are hosted by both pre-Early Cambrian sericitic mica-chlorite schists and Neogene volcanites, the latter comprising tuffs and agglomerates. These units have been affected by hydrothermal alteration controlled by faults resulting in complex, irregular, lateral mineralogical zonation. The occurrence of a siliceous cap on altered schists and in claystone, of quartz veins in schists and tuffs, and the development of explosion cones and pit fillings indicate that alteration in both the schists and the volcanites is due to hydrothermal processes. Altered schists have generally large (locally small) Fe contents, and claystones are generally silicified and have small Fe contents. Kaolinite predominates south and west of Tas°oluk, whereas high (Fe+Ti)-bearing illite + kaolinite predominate in other altered sections. The kaolinite exhibits a stacked micromorphology within altered schists, and the altered volcanites record in situ precipitation, derived from a mechanism of paired dissolution and precipitation. Illite fibres coexist with kaolinite, smectite, chlorite, mica and sericitized feldspar in markedly altered schists, revealing that the illite formed either authigenically or by conversion of smectite to illite. A relative increase in Cr+Ni and decrease in Sr+Ba in the kaolinite deposits and their schistose host rock relative to the upper level of the kaolinite deposits and their volcanic parent rocks came about by the alteration of chlorite, mica and feldspar in the sericitic mica-chlorite schists, and feldspar, glass shards and schist fragments in the volcanites as a result of extensive faulting, fracturing and hydrothermal activity during Late Miocene-Pliocene volcanism, which contributed to the development of kaolinite deposits under acidic environmental conditions. With regard to industrial applications, the low-Fe kaolinized schists are suitable for use in refractories and paper coatings, while the claystone is suitable for use in ceramics and in the white-cement industry.

Mineralogy, micromorphology, geochemistry and genesis of a hydrothermal kaolinite deposit and altered Miocene host volcanites in the Hallaçlar area, Uşak, western Turkey

“…Early Miocene and continued to the end of the Miocene (Seyitoglu et al, 1997;Yılmaz, 1989), resulting in the development of kaolinite occurrences. Hydrothermal kaolinite deposits in Turkey typically occur in Neogene volcanites (Kadir & Karakas°, 2002;Arslan et al, 2006;Ece & Schroeder, 2007;Sayın, 2007;Ece et al, 2008), Palaeozoic granite-granodiorite complexes (Seyhan, 1978;Kadir & Kart, 2009), and pre-Early Cambrian metamorphites (Kadir & Akbulut, 2009).…”

Sediment-Hosted Kaolin Deposit from Çakmaktepe (Uşak, Turkey): its Mineralogy, Geochemistry, and Genesis

“…The zonation of the minerals from the outer zone to the inner zone in the argillic alteration serves as the most important indicator of the hydrothermal origin of the kaolins in the KBV. Such lateral zonation of clay minerals has been observed in many hydrothermally altered magmatic rocks due to the irregular distribution of the discontinuous horizons with different permeabilities and porosities Kadir and Akbulut, 2009;Kadir and Erkoyun, 2012). Physicochemical and environmental conditions controlled the formation of kaolinite, alunite, and smectite in these kaolins (Sayın, 2007;Kadir et al, 2011;Ece et al, 2013).…”

Alteration of glassy volcanic rocks to Naand Ca-smectites in the Neogene basin of Manisa, western Anatolia, Turkey

“…In general, seafloor alteration and/or atmospheric weathering processes are considered to be responsible for the formation of most smectites. While silica polymorphs, kaolinite, gypsum, opaque minerals and alunite form under strong acidic conditions, smectite may form under slightly acidic to slightly alkaline conditions (Wirsching et al, 1990;Kadir & Akbulut, 2009;Erkoyun & Kadir, 2011). Thus, the pH of the solution gradually becomes alkaline with the release of the alkalis and montmorillonites may precipitate from the solution (Karakaya et al, 2011a,b).…”