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Evolution of the microstructure and crystallographic orientation during shell growth in Psilunio littoralis and Nautilus belauensis

Published online by Cambridge University Press:  05 July 2018

P. Alvarez-Lloret*
Affiliation:
Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avd. Fuentenueva s/n, 18002 Granada, Spain
A. B. Rodriguez-Navarro
Affiliation:
Departamento de Mineralogía y Petrología, Facultad de Ciencias, Universidad de Granada, Avd. Fuentenueva s/n, 18002 Granada, Spain
A. G. Checa
Affiliation:
Departamento de Estratigrafía y Paleontología, Facultad de Ciencias, Universidad de Granada, Avd. Fuentenueva s/n, 18002 Granada, Spain
*

Abstract

Thin sections of shells from different species of mollusc have been analysed by X-ray synchrotron diffraction using the BM16 at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. A sequence of 2-D X-ray diffraction patterns were acquired in transmission mode at regular intervals across the shell thickness. From the 2D patterns, 2θ- and χ-scans were calculatedan d analysed. We studied the evolution of the shell microstructures by analysing several parameters from calculated scans: (1) the intensity of the most intense aragonite reflections in the calculated 2θ scans; (2) the crystallinity calculated from the full width at half maximum values of the main reflections in those scans; and (3) the degree of orientation of crystals, measured from the angular width (in angle) of the arches displayed in the Debye-Scherrer rings which appeared in the 2D diffraction patterns. The determined parameters displayed sharp changes at the transitions between microstructurally distinct shell layers indicating that the microstructural switch occurred very rapidly and was precisely controlled.

Type
Research Article
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2008

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References

Checa, A.G. and Rodriguez-Navarro, A.B. (2001) Geometrical and crystallographic constraints determine self-organization of the shell microstructures in Unionida. (Bivalvia:Mollusca). Proceedings of the Royal Society of London, Biological Sciences, 268, 771–778.CrossRefGoogle Scholar
Rodríguez-Navarro, A.B. (2006) XRD2DScan: a new software for polycrystalline materials characterization using two-dimensional X-ray diffraction. Journal of Applied Crystallography, 39, 905–909.CrossRefGoogle Scholar
Taylor, J.D., Kennedy, W.J. and Hall, A. (1969) Shell structure and mineralogy of the Bivalvia. Introduction. Nuculacae-Trigonacae. Bulletin of the British Museum (Natural History), Zoology Serie. 3, Supplement, 1–125.Google Scholar
Taylor, A. and Sinclair, H. (1945) On the determination of lattice parameters by the Debye-Scherrer method. Proceedings of the Physical Society, 57, 126–135.CrossRefGoogle Scholar