Mineralogical and Geochemical Properties of the Na- and Ca-Bentonites of Ordu (Ne Turkey)

Abstract

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.

An Integrated Geochemical and Mineralogical Approach for the Evaluation of Zn Distribution in Long-Term Sludge-Amended Soil

“…The OM observation of the thin sections reveals that euhedral amphibole prismatic crystals begin to weather along the enlarged cleavage planes (Figure 5(a)) where SEM shows the crystallization of clay minerals with the typical honeycomb texture of the smectite (Figure 5(b)). These characteristic features are commonly observed in the weathered rocks and soils [24] [25]. The weathering intensity increases in the Bw horizons where amphibole crystals appears highly fragmented into 20 -100 µm organized residues by the opening of the intramineral microcracks, up to 50 µm wide (Figure 5(c)).…”

Sorption and distribution of Zn in a sludge-amended soil: influence of the soil clay mineralogy

“…montmorillonite, Sap. saponite typical honeycomb texture in the crack plane, which is commonly observed in weathered rocks and soils (Arslan et al 2010;Karakaya et al 2011).…”

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

“…Location of the peloid samples and main tectonic lineaments, volcanic centers, and geothermal areas of Turkey (simplified from Şimşek, 2015). 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.…”