Infrared spectrometric data of basaltic Martian analogues from Mongolian terranes and the Baikal Rift Zone

Kurzfassung

<b>Introduction</b> <p>Infrared spectroscopy has been used to analyse the composition of the rock material of basaltic Martian analogues from Mongolian terranes and the southern part of the Baikal Rift Zone, for comparison of the results with those of Martian missions. Collected samples of basalts derive from various geologic environments (rift zone, island-arc, ophiolite). Microscopic observations in thin sections show diversification of composition and structures of basalts. The most diversified are basalts from the Mandalovoo terrane [1].</p> <b>Transmittance data </b> <p>Transmittance spectra of the samples have been recorded in the range from 400 to 2000 cm⁻¹ for the particle size &lt;25 μm (Fig. 1). The results indicate the presence of the main components of basalts (plagioclases, pyroxenes and olivines), in different proportions, accessory minerals (leucite, analcime) and often of the products of their alteration, e.g. saponite [1]. Comparison with the long wavelength channel data of the Planetary Fourier Spectrometer of the Mars Express mission indicates similar absorption bands of clinopyroxenes in both spectra [1].</p> <b>Emissivity measurements</b> <p>As the next step of the spectroscopic analysis of these basalts, measurements of the emissivity have been taken in the Planetary Emissivity Laboratory (PEL) at the DLR, Berlin, using a Fourier transform infrared spectrometer Bruker VERTEX 80v in the wavelength range from 3 to 50 μm. For each sample we measured the spectra of four particle size ranges: &lt;25 μm, 25-63 μm, 63-125 μm and 125-250 μm (Fig. 2). Using both such wavelength and particle size ranges enlarges the possibilities of observations, interpretation and comparison with the spectrometric data from Martian missions. For the interpretation of the spectra we are using the Berlin Emissivity Database (BED), which presently contain all the most important mineral components of basaltic analogs [2]. According to the previous interpretation, the spectra show distinct absorption bands of plagioclases and pyroxenes. Presence of other characteristic bands of minerals in the spectra usually reflects the intensity of alteration of the basalts.</p> <b>References</b><br /> [1] Gurgurewicz J. and Kostylew J. (2007) EPSC2007-A-00260.<br /> [2] Maturilli A. et al. (2008) Planet. Space Sci., 56, 420-425.<br />