7 results
Clay Minerals in Hydrothermally Altered Volcanic Rocks, Eastern Pontides, Turkey
- Muazzez Çelik, Necati Karakaya, Abidin Temel
-
- Journal:
- Clays and Clay Minerals / Volume 47 / Issue 6 / December 1999
- Published online by Cambridge University Press:
- 28 February 2024, pp. 708-717
-
- Article
- Export citation
-
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 hydrothermal 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 SiO2 and Fe2O3 contents of the hydrothermal bentonites are higher than those of the halmyrolysis smectites; however, the MgO content of both groups is similar. The Na2O and K2O contents of both groups are generally <0.5%. The hydrothermal bentonites are not plastic and have open honeycomb microtextures, although the halmyrolitic smectites are 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 smectite, kaolinite and gypsum, galena, sphalerite, pyrite, goetite, and quartz. The illite has >35 wt. % Al2O3. 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.
Geology and Conditions of Formation of the Zeolite-Bearing Deposits Southeast of Ankara (Central Turkey)
- Muazzez Çelık Karakaya, Necatı Karakaya, Fuat Yavuz
-
- Journal:
- Clays and Clay Minerals / Volume 63 / Issue 2 / April 2015
- Published online by Cambridge University Press:
- 01 January 2024, pp. 85-109
-
- Article
- Export citation
-
The pyroclastic sediments studied here contained varied amounts of zeolite and were formed in the saline alkaline Tuzgölü Basin following the alteration of dacitic volcanic materials during the Early to Late Miocene. The present study focused on the geological-geochemical properties of the zeolites and describes their formation. Mineralogical and chemical compositions were determined by X-ray diffraction, scanning electron microscopy, optical microscopy, and inductively coupled plasma mass spectrometry. Results indicated that the zeolitic tuffs consisted mainly of heulandite/clinoptilolite (Hul/Cpt), chabazite, erionite, and analcime associated with smectite. Smectite, calcite, and dolomite are abundant in the clay and carbonate layers which alternate with the zeolitic tuffs. K-feldspar, gypsum, and hexahydrite (MgSO4·6H2O) were also found in some altered tuffs and clay-marl layers as accessory minerals. The zeolite and other authigenic minerals showed weak stratigraphic zonation. Some vitric tuff layers contained no zeolite minerals and others were found to consist of almost pure Hul/Cpt and chabazite layers with economic potential. The rare earth elements (REE), large ion lithophile elements (LILE), and high-field strength elements (HFSE) in the Hul/Cpt-rich tuffs and vitric tuffs were enriched or depleted relative to the precursor rock, while many major elements were slightly or significantly depleted in all zeolitic tuffs. The amounts of REE in the chabazite- and erionite-rich tuffs were generally smaller than those in the precursor rock. The middle and heavy REE (MREE and HREE, respectively) were abundant in the Hul/Cpt-rich tuffs, tuffs, and smectitic bentonites. Chondrite-normalized REE values of the sample groups are characterized by sub-parallel patterns with enrichment in LREE relative to HREE. The mineral assemblages and geological setting indicated that zeolite diagenesis occurred in a saline-alkaline basin. The δ18O and δD compositions of the Hul/Cpt, chabazite, and smectite indicated that the minerals formed at low to moderate temperatures and that some of the zeolitization occurred due to diagenetic alteration under closed-system conditions that varied according to the nature of the basin and with the composition and physical properties of the volcanic materials.
Mineralogical and Geochemical Properties of the Na- and Ca-Bentonites of Ordu (Ne Turkey)
- Muazzez Çelik Karakaya, Necati Karakaya, Şuayip Küpeli
-
- Journal:
- Clays and Clay Minerals / Volume 59 / Issue 1 / February 2011
- Published online by Cambridge University Press:
- 01 January 2024, pp. 75-94
-
- Article
- Export citation
-
A number of different types of bentonite deposits formed by hydrothermal alteration and diagenetic processes are to be found in the Ordu area of the Eastern Black Sea region. The Ca- and Na-bentonite deposits are related to Upper Cretaceous tholeitic to calc-alkaline volcanites, predominantly dacite and andesite, and also include rhyodacite with lesser basalt and their pyroclastic equivalents. In the present study, dacite (PR1), perlite (PR2), moderately altered rocks (MPR), and Na- and Ca-bentonites were studied to describe and compare their mineralogical and geochemical properties and their conditions of formation by means of X-ray diffraction, optical microscopy, scanning electron microscopy, and chemical analytical techniques.
Ca-bentonites, except for smectite, contain opal-CT, feldspar, biotite, and rarely pyrite, while Na-bentonites contain smectite and less feldspar, opal-CT, kaolinite, and illite.
Progressive alteration of the PR2 caused depletion in K2O and Na2O and enrichment in MgO and CaO in all of the Ca-bentonite samples. Na2O was depleted in all of the Na-bentonites and in most of the MPR. The medium and heavy rare earth elements (MREE and HREE) show mass gain or mass loss in the Na-bentonites. The HREE show nearly immobile behavior in the Ca-bentonites. The rare earth elements (REE) and transition elements (TRE) mostly gained mass in the Ca-bentonites in contrast to Na-bentonites. Large-ion lithophile elements (LILE) are strongly depleted in all of the bentonites. The LREE, MREE, and HREE were strongly depleted in most of the MPR samples. TiO2, Lu, Tm, and Tb show immobile behavior in all samples.
PR1 exhibits a slightly positive Eu anomaly. Two MPR samples show slightly positive Eu anomalies (1.03, 1.13), and one Na-bentonite sample displays a slightly positive Eu anomaly (1.04). Most of the Nabentonites have weakly negative Eu anomalies, whereas perlite and the Ca-bentonite have a strongly negative Eu anomaly. The PR1, PR2, MPR, and Na-bentonite present a positive Ce anomaly, and the Ca-bentonite shows a moderately negative Ce anomaly. The Ca-montmorillonites are mainly hydrothermal in origin and derived from alteration of volcanoclastic material in situ and/or in the subaerial environment. The Na-montmorillonites formed by alteration and diagenesis of volcanoclastic material in the sedimentary basin.
Mineralogical and Chemical Properties and the Origin of Two Types of Analcime in SW Ankara, Turkey
- Necati Karakaya, Muazzez Çelik Karakaya, Abidin Temel
-
- Journal:
- Clays and Clay Minerals / Volume 61 / Issue 3 / June 2013
- Published online by Cambridge University Press:
- 01 January 2024, pp. 231-257
-
- Article
- Export citation
-
Authigenic analcimes were observed in different amounts in Miocene units in central Anatolia, Turkey. Two types of analcime occurrences were defined: (1) as continuous but inhomogeneous concentrations varying from 3 to 75 wt.% in lacustrine sedimentary rocks; and (2) as low concentrations (between 3 and 20%) and discontinuous components in the tuffs and claystones intercalated with tuff. The type 2 analcimes have been investigated by many researchers while the origin and properties of the sedimentary analcimes, which are widespread in different parts of Turkey, have not been clarified. The present study focused on the genesis and the mineralogical and geochemical properties of both types of analcime. The analcimes were investigated using X-ray diffraction, optical microscopy, scanning electron microscopy, and chemical analytical methods. In the first type, other than volcaniclastic material, analcime is the only zeolite mineral. The first type of analcime was associated mainly with montmorillonite, dolomite, and feldspar and sometimes with calcite, and rarely with illite and kaolinite. The second type of analcime was found as an accessory mineral accompanied by montmorillonite, feldspar, and heulandite/clinoptilolite, and more rarely by erionite, kaolinite, and mica. The pyroclastic rocks are chemically classified into two subgroups, dacitic and andesitic rocks, with an intermediate to high silica content and a high percentage of alkali cations. Analcime in the pyroclastics intercalated with clay layers commonly replaced early-formed zeolites, such as clinoptilolite or volcanic materials. The first type of analcime was not formed from precursor zeolites and had a different origin than the second type. Type 1 analcime contains larger amounts of Si (34.19 to 34.68 Si per unit cell) and less Al and Na than in theoretical analcime. The theoretical structural formula of analcime is Na16(Al16Si32O96)H2O. The strongly decomposing feldspar and clay minerals (in particular montmorillonite and partially illite) of the older formations and the dissolution of halite and also soda minerals, e.g. thenardite and glauberite, allow the authigenic formation of type 1 analcime, dolomite, K-feldspar, and montmorillonite in a saline and highly alkaline environment such as the marginal part of Lake Tuzgölü. Type 2 analcime may have been precipitated directly from solution, pyroclastic material, or precursor zeolite minerals in saline and alkaline lake water.
Mineralogical and Geochemical Characteristics and Genesis of the Sepiolite Deposits at Polatli Basin (Ankara, Turkey)
- Muazzez Çelik Karakaya, Necati Karakaya, Abidin Temel
-
- Journal:
- Clays and Clay Minerals / Volume 59 / Issue 3 / June 2011
- Published online by Cambridge University Press:
- 01 January 2024, pp. 286-314
-
- Article
- Export citation
-
The Middle—Upper Miocene—Pliocene sediments near Polatlı contain commercial sepiolitic clay deposits. The sepiolite-rich Polatlı basin sediments were studied to describe the sepiolitic clay deposits of the area and to assess the environments of formation using X-ray diffraction, optical and scanning electron microscopy, and chemical analysis. The Polatlı basin is an elongated, rift-related graben trending NE—SW in central Turkey, filled with continental Late Miocene to Early Pliocene sediments. The sediments which comprise claystone, marl and limestone, dolostone, and evaporites are characteristic deposits of low-salinity, playa-lake depositional environments. These sepiolite-rich deposits include sepiolite, dolomite, and calcite, with minor amounts of palygorskite, quartz, moganite, amorphous silica (opal-CT), and feldspar.
The sepiolite shows all the characteristic X-ray diffraction reflections of that mineral, whereas amorphous silica containing sepiolite shows some of the characteristic reflections of sepiolite, but with somewhat broader and less intense basal reflections. In the siliceous deposits, the long, fibrous, and filamentous aggregates of the sepiolite were converted to thick, short fibers, low in Mg, and showing transition to amorphous silica.
Major and trace elements (e.g. Si, Al, Fe, Mg, Sr, Ba, etc.) were found almost exclusively in Mg-rich smectitic claystone and detrital silicate-rich rocks, whereas Mg, Ca, and some Si were concentrated in the neoformed minerals in the basin. The rare-earth elements (REE) and some of the high-field strength elements (HFSE), large ion lithophile elements (LILE), and transition elements (TRE) patterns were similar for detrital silicate-rich rocks and formed from neoformed mineral lithologies. The REE, TRE, LILE, and some of the HFSE contents of limestone, dolostone, and sepiolitic claystone were similar while those of detrital silicate-rich rocks and Mg-rich smectitic claystones were similar to each other. PAAS-normalized REE and other trace-element patterns were typically subparallel and depleted in neoformed minerals. All sample groups had positive Eu* anomalies, except Mg-rich smectite (0.80). Limestone, dolostone, and amorphous silica compounds showed slightly negative Ce* anomalies, whereas sepiolitic claystones, Mg-rich smectitic claystones, and detrital silicate-rich rocks had a slightly positive Ce* anomaly.
Mineralogical and physico-chemical properties of Heu-type zeolitic rocks SE of Ankara, central Turkey
- Muazzez Çelik Karakaya, Necati Karakaya, Fuat Yavuz
-
- Journal:
- Clay Minerals / Volume 52 / Issue 2 / June 2017
- Published online by Cambridge University Press:
- 02 January 2018, pp. 191-202
-
- Article
- Export citation
-
This study focused on the mineralogical and physico-chemical properties of heulandite/clinoptilolite (Heu/Cpt)-rich zeolitic tuffs SE of Ankara (Turkey) and evaluated their potential for use as adsorbents. The main Heu/Cpt minerals correspond to the intermediate type and the Cpt-type of the heulandite series. Minor chabazite, erionite and rarely analcime and accessory feldspars, mica, smectite, and quartz were also detected. Three types of Heu were recognized according to their thermal behaviour. Cpt (type-III Heu) was thermally stable at 600°C, whereas type-I Heu collapsed and type-II Heu partially collapsed. The Si/Al ratios of the Hul/Cpt ranged from 3.54 to 5.03, the Γ parameter (Γ = Ca/Al + 0.115*Al) varied between 0.78 and 1.85 and Al + Fe3+ varied between 6.27 and 8.00. The Na, K and Ca contents of Heu/Cpt varied widely and the Heu had an intermediate composition between types II and III. The Mg + Ca content is greater than the Na + K content in Heu-type II and smaller in Heu-type III zeolites. The BET surface area and the pore-size of the samples varied between 10.15 and 194.27 m2/g, and between 1.41 and 12.42 nm, respectively. The N2 adsorption and desorption isotherms were comparable, but the adsorption/desorption capacity is greater in type III than in type II Heu zeolites. The cation exchange capacities of the Heu/Cpt-rich samples ranged from 185 to 280 meq/100 g.
Radioactivity concentrations and dose assessments of therapeutic peloids from some Turkish spas
- Muazzez Çelik Karakaya, Mahmut Doğru, Necati Karakaya, Hasibe Cingilli Vural, Fatih Kuluöztürk, Sultan Şahin Bal
-
- Journal:
- Clay Minerals / Volume 50 / Issue 2 / June 2015
- Published online by Cambridge University Press:
- 02 January 2018, pp. 221-232
-
- Article
- Export citation
-
The activity concentrations of natural radionuclides in peloids were studied to assess the radiologic hazard from 18 Turkish spas. The peloids are mainly used for therapeutic treatments, rheumatic diseases and aesthetic purposes. The concentrations of the natural radionuclides 226Ra, 232Th, 40K and 137Cs were determined with a gamma ray spectrometer using a HPGe detector. The average activity concentrations of 226Ra, 232Th, 40K, and 137Cs in the peloids studied were 110.69, 71.52, 576.48 and 0.447 Bq/kg, respectively. The radium equivalent activities in the peloid samples ranged from 63.3 to 766.77 Bq/kg. The absorbed dose rate (Dout) varied between 37.52 and 330.67 nGy/h and most of the observed spa doses are greater than the worldwide recommended values. The annual effective dose values range from 0.26 to 2.78 μSv/y. The annual gonadal dose equivalents of the samples vary from 224.07 to 2283.55 with a mean of 821.99 μSv/y.