Chromium-bearing clays in altered ophiolitic rocks from Crommyonia (Soussaki) volcanic area, Attica, Greece

Research output: Contribution to journalJournal article – Annual report year: 2018Researchpeer-review

  • Author: Mitsis, I.

    National and Kapodistrian University of Athens, Greece

  • Author: Godelitsas, A.

    National and Kapodistrian University of Athens, Greece

  • Author: Göttlicher, J.

    Karlsruhe Institute of Technology, Germany

  • Author: Steininger, Ralph

    Karlsruhe Institute of Technology, Germany

  • Author: Gamaletsos, P. N.

    Center for Electron Nanoscopy, Technical University of Denmark, Fysikvej, 2800, Kgs. Lyngby, Denmark

  • Author: Perraki, M.

    National Technical University of Athens, Greece

  • Author: Abad-Ortega, M. M.

    CIC Centro de Instrumentación Científica, Spain

  • Author: Stamatakis, M.

    National and Kapodistrian University of Athens, Greece

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Chromium-bearing clays occurring at Crommyonia (Soussaki), Greece, are studied in detail. In this area Mesozoic ultramafic ophiolitic rocks were affected by a Pliocene volcanic activity continuing, nowadays, with intense post-volcanic phenomena. Particularly, the Cr-bearing clays were formed at the margins of the ophiolite into highly altered serpentinized peridotite. These clays were studied by means of x-ray diffraction (powder-XRD), microscopic (SEM-EDS), nanoscopic (TEM-EDS/STEM-HAADF), and spectroscopic (FTIR, XANES) techniques. The XRD and SEM-EDS studies confirmed smectites and halloysites, with average Cr2O3 content ca 6.2 wt % and 4.3 wt%, respectively. The mineralogy and mineral-chemistry of the above unique Cr-clays was also confirmed by TEM-EDS/STEM-HAADF measurements. Subsequent FT-IR investigation indicated the relation of chromium ions with structural hydroxyls whereas a XANES study showed the presence of only Cr(III) in both phases and the absence of Cr(VI). According to the above data, Cr(III) ions should occupy octahedral sites in the structure of the studied clays. Geochemical data indicated high enrichment in Cr, and also in As, Se, Ni, V, Sc, Tl, when compared to Upper Continental Crust (UCC), and in Cr when compared to average global peridotite and primitive mantle. The formation of Cr-bearing clays is attributed to additional alteration of serpentinized peridotite minerals (such as Cr-spinels), due to hydrothermal fluids leaching different elements from the volcanic, sedimentary, and ophiolitic rocks of the area.
Original languageEnglish
JournalApplied Clay Science
Volume162
Pages (from-to)362-374
Number of pages13
ISSN0169-1317
DOIs
Publication statusPublished - 2018
CitationsWeb of Science® Times Cited: No match on DOI

    Research areas

  • Clays, Smectite, Chromium, Nanoscopy, Synchrotron, Greece
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