Journal article
(Original article)


The structure of haplobasaltic glasses investigated using X-ray absorption near edge structure (XANES) spectroscopy at the Si, Al, Mg, and O K-edges and Ca, Si, and Al L-2,L-3-edges


Publication Details
Author(s): Moulton B, Henderson G, Sonneville C, O'Shaughnessy C, Zuin L, Regier T, de Ligny D
Publisher: Elsevier
Publication year: 2016
Volume: 420
Pages range: 213-230
ISSN: 0009-2541
Language: English

Abstract

X-ray absorption near-edge structure (XANES) spectroscopy has been used to investigate the local structural environments around each of the elements within the haplobasaltic system. The XANES results reveal both, linear changes in Ca, O and Si whereas non-linear changes are also observed for Si as well as Al and Mg. Unexpectedly, both Si and Al spectra show complex edge structure that varies non-linearly across the join. The Si L-2,L-3-edge results suggest that the Si environment in An100 is very similar to that in crystalline anorthite whereas the Di100 and diopside spectra show large offsets. The L-3 and L-2 peaks display a linear behavior where as peak B of the Si L-2,L-3 spectra displays a non-linear behavior displaying a maximum position at the Di40 and Di100 compositions and decreasing in between. We estimate the Si-O bond length from shift in the peak B position which suggests a change in bond length between 1.58 and 1.66 angstrom across the join. The Al K-edge spectra suggests that there is a constant decrease in the inter-tetrahedral angle as Al is added. The local Mg environment displays non-linear changes in intensity and for compositions with An content greater than Di40 it appears that Mg-[4] plays an important role whereas Mg-[5] is dominant in diopside-rich melts, though octahedral coordinated Mg cannot be ruled out. The oxygen environment appears similar to crystalline anorthite in the haplobasaltic system. Calcium is present in highly distorted sites that are dominantly Ca-[7] in anorthite-rich glasses where as Ca-[8] is more important in diopside-rich glasses. These results provide additional independent constraints on the atomic structure of haplobasaltic silicate melts and highlight the need for further investigation into the relationships between network formers, modifiers and the oxygen to which they are bound. (C) 2015 Elsevier B.V. All rights reserved.



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How to cite
APA: Moulton, B., Henderson, G., Sonneville, C., O'Shaughnessy, C., Zuin, L., Regier, T., & de Ligny, D. (2016). The structure of haplobasaltic glasses investigated using X-ray absorption near edge structure (XANES) spectroscopy at the Si, Al, Mg, and O K-edges and Ca, Si, and Al L-2,L-3-edges. Chemical Geology, 420, 213-230. https://dx.doi.org/10.1016/j.chemgeo.2015.11.016

MLA: Moulton, Benjamin J. A., et al. "The structure of haplobasaltic glasses investigated using X-ray absorption near edge structure (XANES) spectroscopy at the Si, Al, Mg, and O K-edges and Ca, Si, and Al L-2,L-3-edges." Chemical Geology 420 (2016): 213-230.

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