Reflectance of silicate glasses in the mid-infrared region (MIR): Implications for planetary research

• Published in: Icarus (New York, N.Y. 1962) N.Y. 1962), 2022-12, Vol.388, p.115222, Article 115222
• Main Authors: Pisello, Alessandro, Ferrari, Marco, De Angelis, Simone, Vetere, Francesco P., Porreca, Massimiliano, Stefani, Stefania, Perugini, Diego
• Format: Article
• Language: English
• Subjects: Mid-infrared; Reflectance; Silicate glasses; Tools for planetary investigation; Volcanism
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2022.115222

Volcanic phenomaena shaped the surface of all terrestrial planets in the solar system, and silicate glasses represent a major component in pyroclastic deposits and lavas. Spectral features of silicate glasses therefore influence spectral characteristics of large portions of planetary surfaces. In this study, experimental petrology techniques have been used to produce 19 silicate glass samples having natural chemical composition corresponding to four of the most common magmatic series on planet Earth. Reflectance of such products was investigated in the mid-infrared region (MIR) to observe the evolution of their spectral characteristics with changing degree of evolution (expressed as silica content) and alkaline content. We have observed how chemical features have a clear influence in shifting the spectral features (to lower wavelengths with increasing silica, such as for previously studied volcanic rocks) and on the spectral shape, which is substantially different between mafic and highly silicic products. This allowed us to propose a model to retrieve chemical information (SiO2 and SiO2 + Al2O3 + TiO2 content) from the wavelength at which spectral features (CF and RBpeak) occur. Moreover, by comparing our results with previous MIR studies we have observed that our model can be applied, to a certain extent, to interpret chemical fingerpint volcanic rocks in general. Here, it is also shown how granulometry influences spectral shape, but does not affect spectral shift. This study will be useful to interpret planetary information and assess how amorphous silicate phases influence spectral characteristics of volcanic areas on planetary surfaces. •A set of 19 silicate glasses with complex chemical composition were produced starting from natural material.•Samples were characterized with reflectance in the MIR, and we individuated relationships between chemical composition (Si, Ti and Al content) and spectral characteristics (shape, albedo).•A model for the retrieval of chemical information from wavelength position of spectral features is proposed•Results from such investigation will be useful to interpret occurrence of volcaniclastic products on planetary surfaces.