title: Raman spectra of Martian glass analogues: A tool to approximate their chemical composition.
abstract: Raman spectrometers will form a key component of the analytical suite of future planetary rovers intended to investigate geological processes on Mars. In order to expand the applicability of these spectrometers and use them as analytical tools for the investigation of silicate glasses, a database correlating Raman spectra to glass composition is crucial. Here we investigate the effect of the chemical composition of reduced silicate glasses on their Raman spectra. A range of compositions was generated in a diffusion experiment between two distinct, iron-rich end-members (a basalt and a peralkaline rhyolite), which are representative of the anticipated compositions of Martian rocks. Our results show that for silica-poor (depolymerized) compositions the band intensity increases dramatically in the regions between 550-780 cm-1and 820-980 cm-1. On the other hand, Raman spectra regions between 250-550 cm-1and 1000-1250 cm-1are well developed in silica-rich (highly polymerized) systems. Further, spectral intensity increases at ~965 cm-1related to the high iron content of these glasses (~7-17 wt % of FeOtot). Based on the acquired Raman spectra and an ideal mixing equation between the two end-members we present an empirical parameterization that enables the estimation of the chemical compositions of silicate glasses within this range. The model is validated using external samples for which chemical composition and Raman spectra were characterized independently. Applications of this model range from microanalysis of dry and hydrous silicate glasses (e.g., melt inclusions) to in situ field investigations and studies under extreme conditions such as extraterrestrial (i.e., Mars) and submarine volcanic environments.
authors.affiliation: Department of Earth and Environmental Sciences Ludwig-Maximilians-Universität Munich Germany.
authors.forename: Danilo
authors.initials: D
authors.lastname: Di Genova
authors.affiliation: Dipartimento di Scienze della Terra Università degli Studi di Torino Turin Italy.
authors.forename: Stephan
authors.initials: S
authors.lastname: Kolzenburg
authors.affiliation: Dipartimento di Scienze Università degli Studi Roma Tre Rome Italy.
authors.forename: Alessandro
authors.identifier: 0000-0002-5483-5623
authors.initials: A
authors.lastname: Vona
authors.affiliation: Laboratoire Magmas et Volcans Université Blaise Pascal Aubière France.
authors.forename: Magdalena Oryaëlle
authors.initials: MO
authors.lastname: Chevrel
authors.affiliation: Department of Earth and Environmental Sciences Ludwig-Maximilians-Universität Munich Germany.
authors.forename: Kai-Uwe
authors.initials: KU
authors.lastname: Hess
authors.affiliation: Géomatériaux, CNRS-IPGP UMR 7154 Paris Sorbonne Cité Paris France.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Neuville
authors.affiliation: Department of Earth and Environmental Sciences Ludwig-Maximilians-Universität Munich Germany.
authors.forename: Werner
authors.initials: W
authors.lastname: Ertel-Ingrisch
authors.affiliation: Dipartimento di Scienze Università degli Studi Roma Tre Rome Italy.
authors.forename: Claudia
authors.initials: C
authors.lastname: Romano
authors.affiliation: Department of Earth and Environmental Sciences Ludwig-Maximilians-Universität Munich Germany.
authors.forename: Donald B
authors.initials: DB
authors.lastname: Dingwell
keywords: Mars; Raman spectroscopy; chemical analysis; glasses; remote sensing; volcanology