Enhanced crystal fabric analysis of a lava flow sample by neutron texture diffraction: A case study from the Castello d'Ischia dome. (31st January 2013)

• Record Type: Journal Article
• Authors: Walter, Jens M.; Iezzi, Gianluca; Albertini, Gianni; Gunter, Mickey E.; Piochi, Monica; Ventura, Guido; Jansen, Ekkehard; Fiori, Fabrizio
• Is Part Of: Geochemistry, geophysics, geosystems. Volume 14:Number 1(2013)
• Page Start: 179
• Page End: 196
• Publication Date: 2013-01-31
• Subjects: neutron diffraction -- texture -- crystal fabric -- lava -- trachyte -- image analysis; Geochemistry -- Periodicals; Geophysics -- Periodicals; Earth sciences -- Periodicals; 550.5
• DOI: 10.1029/2012GC004431
• Languages: English
• ISSNs: 1525-2027

Abstract

Abstract : [1] The crystal fabric of a lava has been analyzed for the first time by neutron texture diffraction. In this study we quantitatively investigate the crystallographic preferred orientation of feldspars in the Castello d'Ischia (Ischia Island, Italy) trachytic exogenous dome. The crystallographic preferred orientation was measured with the monochromatic neutron texture diffractometer SV7 at the Forschungszentrum Jülich in Germany and a Rietveld refinement was applied to the sum diffraction pattern. The complementary thin section analysis showed that the three‐dimensional crystal shape and the corresponding shape preferred orientation are in agreement with the quantitative orientation distributions of the neutron texture data. The (0 k 0) crystallographic planes of the feldspars are roughly parallel to the local flow bands, whereas the other corresponding pole figures show that a pivotal rotation of the anorthoclase and sanidine crystals was active during the emplacement of this lava dome. In combination with scanning electron microscopy investigations, electron probe microanalysis, XRF, and X‐ray diffraction, the Rietveld refinement of the neutron diffraction data indicates a slow cooling dynamic on the order of several months during their crystallization under subaerial conditions. Results attained here demonstrate that neutron texture diffraction is a powerful tool that can be applied to lava flows. Key Points: Neutron texture analysis is a strong tool for quantitative lava fabric analysis Neutron diffraction is a strong tool to reveal cooling histories of lava flows Neutron texture diffraction is a strong tool to reveal lava flow kinematics