Clay Minerals in Hydrothermally Altered Volcanic Rocks, Eastern Pontides, Turkey

Abstract

Abstract--Extensive hydrothermal alteration is observed around volcanogenic massive sulfide deposits. These deposits are related to Late Cretaceous volcanism in various parts of the Eastern Pontide province. Mineral assemblages resulting from alteration consist of mostly clay minerals and silica polymorphs, some sulfate minerals, and scarce zeolite minerals. The clay minerals are kaolinite, illite, and smectite. These minerals were examined using X-ray diffraction (XRD), scanning electron microscopy (SEM)-energy dispersive spectrometry (EDS), X-ray fluorescence spectroscopy (XRF), and differential thermal analysis (DTA)-thermal gravimetry (TG) techniques. The illite and the toseki deposits are a result of hydrothermal alteration of dacitic-andesitic volcanites. Two groups of bentonite deposits occur; the first mainly formed by hydrothermai solution whereas the second group resulted from halmyrolysis.The smectite in these alteration zones is generally montmorillonitic in composition and the interlayer cation is mostly Ca and lesser amounts of Na. The SiO 2 and F%O 3 contents of the hydrothermal bentonites are higher than those of the halmyrolysis smectites; however, the MgO content of both groups is similar. The Na20 and K~O contents of both groups are generally <0.5%. The hydrothermal bentonites are not plastic and have open honeycomb microtextures, although the halmyrolitic smectites axe plastic with ultrafine and rod-shaped textures. Illite, which contains some smectite layers, is a 1M polymorph, and has an asymmetry to the low-angle side of the XRD peaks. The impure illite deposits contain various combinations of smeetite, kaolinite and gypsum, galena, sphalerite, pyrite, goetite, and quartz. The illite has >35 wt. % A1203. The toseki raw material, which may be possibly useful as a porcelain raw material, is composed mainly of illite, kaolinite and quartz, or illite and quartz. The crystallinity of the kaolinite is poor.

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

“…The enrichment of aluminum and potassium relative to sodium, calcium, magnesium and iron in illites (or fine grained micaceous occurrences, ie., sericites) seems to be related to the host-rock composition and nature of hydrothermal alteration at a high water/rock ratio and low pH conditions (Berger and Velde, 1992;Meunier and Velde, 2004). Similar compositions for hydrothermal illites associated with massive sulfide deposits from western Pontides was reported by Celik et al (1999). Low Fe-and Mg-bearing illites associated with volcanic hosted hydrothermal ore deposits have been proposed by these authors as due to the presence of sulfides (pyrite, chalcopyrite) or oxides (hematite), and a low content of Mg in host-rock, respectively.…”

“…Major element compositions of illites, volcanic host-rocks (rhyolite and rhyodacite) from the study area and hydrothermal illite from the Ulubey area of the Eastern Pontides (Celik et al, 1999), for comparison, are presented in Table 3. Different illites are compositionally similar with only minor variability but are distinctly different to the composition of the volcanic rocks (Fig.…”

“…The than a pressure effect (e.g., Sassi and Scolari, 1974;Guidotti and Sassi, 1986 (Shirozu and Higashi, 1972;Meunier and Velde, 1982;Inoue et al, 1987Inoue et al, , 1988Drits et al, 1993;Inoue and Kitagawa, 1994;Drews-Armitage et al, 1996;Celik et al, 1999;Yan et al, 2001;Bove et al, 2002;Schleicher, 2006).…”

Kübler Index and K-Ar Ages of Illite in the Yinshan Polymetallic Deposit, Jiangxi Province, South China: Analyses and Implications

“…Illite has also been observed in very lowgrade metamorphic rocks (Eberl, 1993). Daniel et al (1975), Diba and Williams (1983), Bechtel et al (1996Bechtel et al ( , 1999Bechtel et al ( , 2000, Celik et al (1999), and Li et al (2003) have discussed the crystallinity of hydrothermal illite and its relation to ore fluids but full understanding of the relationship remains unclear. This paper discusses the origin of illite sampled from altered volcanic-subvolcanic rocks and altered phyllite in the Yinshan polymetallic ore deposit located in Jiangxi Province of South China, and its relationship with ore-forming fluids and mineralization processes based on measurement of the Kübler indices and K-Ar ages of the illite.…”

The physical and physicochemical properties of some Turkish thermal muds and pure clay minerals and their uses in therapy

“…minerals, with mineralogical and chemical properties as previously defined by Çelik et al (1999), Karakaya MÇ et al (2001, 2011a, 2011b), and Karakaya N et al (2011 were collected from different areas of Turkey. The pure illite and smectite samples were collected from the vicinity of Ordu in the northern part of Turkey (Çelik et al, 1999;Karakaya MÇ et al, 2011a, 2011b. The kaolinite and sepiolite samples were taken from the Konya and Ankara regions located in central Turkey, respectively (Karakaya et al, 2001;Karakaya N et al, 2011).…”