Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Web of Science (5) Citing Articles via Google Scholar Google Scholar Articles by de la Fuente, S. Articles by Linares, J. Search for Related Content GeoRef GeoRef Citation

ELECTRON MICROSCOPY STUDY OF VOLCANIC TUFF ALTERATION TO ILLITE-SMECTITE UNDER HYDROTHERMAL CONDITIONS

¹ Estación Experimental del Zaidín, CSIC, Profesor Albareda, 1, 18008 Granada, Spain
² Istituto di Ricerca sulle Argille, CNR, Via S. Loja, 85050 Tito Scalo (Pz), Italy

E-mail of corresponding author: sandra{at}eez.csic.es

Experimental alteration of volcanic tuff from Almería, southeastern Spain, was performed in solutions with different Na/K ratios (0.01, 1, 10, and 100), different total salt concentrations (0.01, 0.1, 0.2, 0.33, and 1 M), and in deionized water, at 60, 80, 120, and 160°C, for periods of 60, 90, 180, and 360 d. Two particle size fractions of volcanic tuff were used: 10–200 and 20–60 µm. Alteration products were examined by X-ray diffraction (XRD), Fourier-transform infrared spectroscopy (FTIR), laser-particle size analysis, scanning electron microscopy equipped with an energy dispersive X-ray spectrometer (SEM-EDS), image computer analysis, and transmission electron microscopy with microanalysis (TEM-AEM). XRD detected neoformed phases only in the products from experiments of 180–360 d at high temperatures (120–160°C), and with Na/K ratios above unity and in deionized water. The synthesized phase is a random mixed-layer illite-smectite (I-S) with 75% smectite. The quantity of newly formed I-S, determined by FTIR, ranged between 3–30%. There was no apparent change in grain size and shape of the grains after the experiments as compared to before.

SEM-EDS and TEM-AEM revealed the following alteration sequence: 1) intense etching on glass-grain surfaces; 2) formation of hemispherical morphologies on grain surfaces; 3) precipitation of very thin, individual flakes of illite-smectite on glass-grain surfaces; 4) development of I-S at the edges of glass grains; and 5) development of I-S honeycomb structures either covering large areas of the glass grains or resulting from the complete alteration of glass grains. A direct transformation of glass to I-S seems to be the major reaction mechanism, although there also is evidence of glass dissolution and subsequent I-S precipitation.

Key Words: Hydrothermal Alteration • Illite-Smectite • SEM-EDS • TEM-AEM • Volcanic Tuff

This article has been cited by other articles:

				M. Setti, L. Marinoni, and A. Lopez-Galindo Clay mineral assemblages as indicators of hydrothermalism in the basal part of the CRP-3 core (Victoria Land Basin, Antarctica) Clay Minerals, September 1, 2009; 44(3): 389 - 404. [Abstract] [Full Text] [PDF]

				A. YILDIZ and M. KUSCU Mineralogy, chemistry and physical properties of bentonites from Basoren, Kutahya, W Anatolia, Turkey Clay Minerals, September 1, 2007; 42(3): 399 - 414. [Abstract] [Full Text] [PDF]

				T. Dudek, J. Cuadros, and J. Huertas Structure of mixed-layer kaolinite-smectite and smectite-to-kaolinite transformation mechanism from synthesis experiments American Mineralogist, January 1, 2007; 92(1): 179 - 192. [Abstract] [Full Text] [PDF]

				A. Mirabella, M. Egli, S. Raimondi, and D. Giaccai ORIGIN OF CLAY MINERALS IN SOILS ON PYROCLASTIC DEPOSITS IN THE ISLAND OF LIPARI (ITALY) Clays and Clay Minerals, August 1, 2005; 53(4): 409 - 421. [Abstract] [Full Text] [PDF]

				M. Ddani, A. Meunier, M. Zahraoui, D. Beaufort, M. El Wartiti, C. Fontaine, B. Boukili, and B. El Mahi CLAY MINERALOGY AND CHEMICAL COMPOSITION OF BENTONITES FROM THE GOUROUGOU VOLCANIC MASSIF (NORTHEAST MOROCCO) Clays and Clay Minerals, June 1, 2005; 53(3): 250 - 267. [Abstract] [Full Text] [PDF]

				A. YILDIZ and M. KUSCU Origin of the Basoren (Kutahya, W Turkey) bentonite deposits Clay Minerals, June 1, 2004; 39(2): 219 - 231. [Abstract] [Full Text] [PDF]

				V. C. Hover, V. C. Hover, and G. M. Ashley GEOCHEMICAL SIGNATURES OF PALEODEPOSITIONAL AND DIAGENETIC ENVIRONMENTS: A STEM/AEM STUDY OF AUTHIGENIC CLAY MINERALS FROM AN ARID RIFT BASIN, OLDUVAI GORGE, TANZANIA Clays and Clay Minerals, June 1, 2003; 51(3): 231 - 251. [Abstract] [Full Text] [PDF]

				S. de la Fuente, S. de la Fuente, J. Cuadros, and J. Linares EARLY STAGES OF VOLCANIC TUFF ALTERATION IN HYDROTHERMAL EXPERIMENTS: FORMATION OF MIXED-LAYER ILLITE-SMECTITE Clays and Clay Minerals, October 1, 2002; 50(5): 578 - 590. [Abstract] [Full Text] [PDF]