Orientation distributions of garnet and omphacite in eclogite from the ultra-high pressure Dabie Shan belt in east-central China were determined from neutron diffraction data by the Rietveld method. Diffraction spectra were recorded in 16 sample orientations with seven detectors, with a kappa-geometry texture goniometer at the time-of-flight (TOF) neutron facility at the Intense Pulsed Neutron Source (IPNS). The textures of the two minerals were extracted simultaneously from 16 × 7 = 112 diffraction spectra, covering a large portion of the pole figure. The texture analysis was performed both with the Williams-Imhof-Matthies-Vinel (WIMV) method and the harmonic method, implemented in the program package MAUD. The incomplete pole-figure coverage introduced artificial oscillations in the case of the harmonic method. The discrete WIMV method produced better results, which illustrate a more or less random orientation distribution for cubic garnet. Apparently elongated grains turned out to be layers of randomly oriented crystals. Monoclinic omphacite displays a sharp texture, with [001] parallel to the lineation direction. The texture data obtained by neutron diffraction were verified with EBSP (electron backscatter pattern) measurements.
Rietveld Texture Analysis of Dabie Shan Eclogite from TOF Neutron Diffraction Spectra / Wenk, H. R.; Cont, L.; Xie, Y.; Lutterotti, Luca; Ratschbacher, L.; Richardson, J. W.. - In: JOURNAL OF APPLIED CRYSTALLOGRAPHY. - ISSN 0021-8898. - STAMPA. - 34:(2001), pp. 442-453. [10.1107/S0021889801005635]
Rietveld Texture Analysis of Dabie Shan Eclogite from TOF Neutron Diffraction Spectra
Lutterotti, Luca;
2001-01-01
Abstract
Orientation distributions of garnet and omphacite in eclogite from the ultra-high pressure Dabie Shan belt in east-central China were determined from neutron diffraction data by the Rietveld method. Diffraction spectra were recorded in 16 sample orientations with seven detectors, with a kappa-geometry texture goniometer at the time-of-flight (TOF) neutron facility at the Intense Pulsed Neutron Source (IPNS). The textures of the two minerals were extracted simultaneously from 16 × 7 = 112 diffraction spectra, covering a large portion of the pole figure. The texture analysis was performed both with the Williams-Imhof-Matthies-Vinel (WIMV) method and the harmonic method, implemented in the program package MAUD. The incomplete pole-figure coverage introduced artificial oscillations in the case of the harmonic method. The discrete WIMV method produced better results, which illustrate a more or less random orientation distribution for cubic garnet. Apparently elongated grains turned out to be layers of randomly oriented crystals. Monoclinic omphacite displays a sharp texture, with [001] parallel to the lineation direction. The texture data obtained by neutron diffraction were verified with EBSP (electron backscatter pattern) measurements.File | Dimensione | Formato | |
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eclogite_JAC_2001.pdf
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