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Rythmic changes in crystal chemistry of trioctahedral Cr-chlorites and Cr entrapment: a SEM, EM and Raman study

Published online by Cambridge University Press:  09 July 2018

A. C. Prieto*
Affiliation:
Departamento de Física de la MateriaCondensada, Cristalografía y Mineralogía, Universidad de Valladolid, 47011 Valladolid, Spain
M. -C. Boiron
Affiliation:
UMR CNRS G2R 7566 and CREGU, BP23, 54501, Vandoeuvre les Nancy Cedex, France
M. Cathelineau
Affiliation:
UMR CNRS G2R 7566 and CREGU, BP23, 54501, Vandoeuvre les Nancy Cedex, France
R. Mosser-ruck
Affiliation:
UMR CNRS G2R 7566 and CREGU, BP23, 54501, Vandoeuvre les Nancy Cedex, France
J . A. Lopez
Affiliation:
Departamento de Cristalografía y Mineralogía, Universidad Complutense, 28040 Madrid, Spain
C. García
Affiliation:
Departamento de Física de la MateriaCondensada, Cristalografía y Mineralogía, Universidad de Valladolid, 47011 Valladolid, Spain
*
*E-mail: prieto@fmc.uva.es

Abstract

Back-scattered scanning electron microscopy (SEM) images of Cr-chlorite crystals from Erzerum (Turkey) reveal that the crystals are chemically inhomogeneous and display complex but well defined crystal zoning characterized by growth bands with contrasting chemical features. The chemical zoning has been investigated at the micron scale using an integrated approach, combining BSEM images, in situ chemical analysis by electron microprobe and Raman spectroscopy. Enrichment in Cr, due to octahedral Al substitution, reaches up to 0.7 atoms per half formula, especially in bands where the Mg content is depleted. These substitutions are also depicted at the micron scale on Raman spectra by changes in the v(OH) band intensities and positions that correlate with the Cr content. The Cr-enrichment occurs thus during specific stages of crystal growth, probably in response to changes in the fluid chemistry controlling the relative availability of Cr, Mg and Al in solution.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2003

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References

Bai, T.B., Guggenheim, S., Wang, S.J., Rancourt, D.G. & Koster van Groos, A.F. (1993) Metastable phase relations in the chlorite-H2O system. American Mineralogist, 78, 12081216.Google Scholar
Bailey, S.W. (1975) Cation ordering and pseudosymmetry in layer silicates. American Mineralogist, 60, 175187.Google Scholar
Bailey, S.W. (1986) Re-evaluation of ordering and local charge-bal ance in Ia chlorite. The Canadian Mineralogist, 24, 649654.Google Scholar
Bailey, S.W. (1988) Chlorites: structures and crystal chemistry. Pp. 347398 in: Hydrous Phyllosilicates (exclusive of Micas)(S.W. Bailey, editor). Reviews in Mineralogy , 19. Mineralogical Society of America, Washington, D.C.Google Scholar
Bakhtin, A.I. (1985) The distribution of Fe ions in chlorites. Geokhimiya, 10, 15191523.Google Scholar
Billor, M.Z. & Gibb, F. (2002) The mineralogy and chemistry of the chromite deposits of southern (Kizilda, Hatay and Islahiye, Antep) and Tauric ophiolite belt (Pozanti-Karsanti, Adana), Turkey. 9th Interna tional Platinum Symposium, Billings, Montana (USA).Google Scholar
Blaha, J.J. & Rosasco, G.J. (1978) Raman microprobe spectra of individual microcrystals and fibers of talc, tremolite, and related silicate minerals. Analytical Chemistry, 50, 892896.Google Scholar
Duffy, J.A. (1990) Bonding Energy Levels and Bands in Inorganic Solids. Longman Scientific and Technical, Harlow, Essex, UK, 249 pp.Google Scholar
Farmer, V.C. (1974) The layer silicates. Pp. 331363 in: The Infrared Spectra of Minerals(Farmer, V.C., editor). Monograph 4, Mineralogical Society of London.Google Scholar
Hayashi, H. & Oinuma, K. (1965) Relationship between infra-red absorption spectra in the region of 450 –900 cm–1 and chemical composition of chlorite. American Mineralogist, 50, 476483.Google Scholar
Hayashi, H. & Oinuma, K. (1967) Si-O absorption bands near 1000 cm–1 and OH absorption bands of chlorites. American Mineralogist, 52, 12061210.Google Scholar
Ishii, M., Shimanouchi, T. & Nakahira, M. (1967) Far infrared absorption spectra of layer silicates. Inorganic Chimica Acta, 1, 387392.Google Scholar
Lister, J.S. & Bailey, S.W. (1967) Chlorite polytypism: IV regula r two-layer structure s. American Mineralogist, 5, 16141631.Google Scholar
Nelson, D.O. & Guggenheim, S. (1991) Inferred limitations to the oxidation of iron in chlorite. A singlecrystal high-temperature X-ray study. American Mineralogist, 76, 11931200.Google Scholar
Pampuch, R. & Ptak, W. (1968) Infrared spectra of 1:1 layer silicates. Polska Akademii Nauk. Oddizial Krakowie, Prace Mineral, 15, 7.Google Scholar
Phillips, T.L., Loveless, J.K. & Bailey, S.W. (1980) Cr3+ coordination in chlorites: a structural study of ten chromian chlorites. American Mineralogist, 65, 112122.Google Scholar
Prieto, A.C., Dubessy, J., Cathelineau, M. & Rull, F. (1990) Estudio y caracterizacion de cloritas trioctaedricas por espectroscopia Raman e infra-Rojo. Boletín de la Sociedad Española de Mineralogía, 13, 2534.Google Scholar
Prieto, A.C., Lobon, J.M., Alia, J.M., Rull, F. & Martin, F. (1991a) Thermal and spectroscopic analysis of natural trioctahedral chlorites. Journal of Thermal Analysis, 37, 969981.Google Scholar
Prieto, A.C., Dubessy, J. & Cathelineau, M. (1991b) Structure composition relationships in trioctahedral chlorites: a vibrational spectroscopy study. Clays and Clay Minerals, 39, 531539.Google Scholar
Prieto, A.C., Medina, J., Calvo, B., Alonso, M., Boiron, M.C. & Cathelineau, M. (1993) Estudio y caracterizacion preliminar de cromo-cloritas de Erzarum (Turquia). Boletín de la Sociedad Española de Mineralogía, 16, 101102.Google Scholar
Rosasco, G.J. & Blaha, J.J. (1980) Raman microprobe spectra and vibrational mode assignments of talc. Applied Spectroscopy, 34, 140144.Google Scholar
Rule, A.C. & Bailey, S.W. (1989) Refinement of the crystal structure of a monoclinic ferroan chlinochlore. Clays and Clay Minerals, 35, 129138.Google Scholar
Serratosa, J.M. & Viñas, J.M. (1964) Infrared investigation of the OH bands in chlorites. Nature, 202, 999.Google Scholar
Shirozu, H. (1980) Cation distribution, sheet thickness, and O-OH space in trioctahedral chlorites – an X-ray and infrared study. Mineralogical Journal, 10, 1434.Google Scholar
Shirozu, H. (1985) Infrared spectra of trioctahedral chlorites in relation to chemical composition. Clay Science, 6, 167176.Google Scholar
Shirozu, H. & Ishida, K. (1982) Infrared study of some 7 Å and 14 Å layer. Mineralogical Journal, 11, 161171.Google Scholar
Shirozu, H., Sakasegawa, T., Katsumoto, N. & Oxaki, M. (1975) Mg-lepto-chlorites – IR. Clay Science, 4, 305321.Google Scholar
Smyth, J.R., Dyar, M.D., May, H.M., Bricker, O.P. & Acker, J.G. (1997) Crystal structure refinement and Müssbauer spectroscopy of an ordered, triclinic clinochlore. Clays and Clay Minerals, 45, 544550.Google Scholar
Tricki, R. (1973) Mise au point d’une technique de coupes minces pour l’é tude des minéraux par diffraction électronique. Minéraux argileux. Ing. Doc. thesis University of Strasbourg, France.Google Scholar
Vedder, W. (1964) Correlation between infrared spectrum and chemical composition of micas. American Mineralogist, 49, 736768.Google Scholar
Wang, A. & Valentine, R.B. (2002) Seeking and identifying phyllosilicates on Mars – A simulation study. Lunar and Planetary Science XXXII, 1370.Google Scholar
Wang, A., Freeman, J. & Kuebler, K.E. (2002) Raman spectroscopy characterization of phyllosilicates. Lunar and Planetary Science XXXIII, 1374.Google Scholar
Welch, M.D., Barras, J. & Klinowski, J. (1995) A multinuclear NMR study of clinochlore. American Mineralogist, 80, 441447.Google Scholar
Zheng, H. & Bailey, S.W. (1989) Structures of intergrown triclinic and monoclinic IIb chlorites from Kenya. Clays and Clay Minerals, 37, 308318.CrossRefGoogle Scholar