Integrated spectral-compositional analysis of listvenites, and implications for Mars

Listvenites are extensively carbonated ultramafic rocks such as peridotites and serpentinites that commonly containing carbonates (magnesite, dolomite), quartz, and often the accessory mineral fuchsite—a green, chromium-bearing variety of muscovite. Listvenites form distinctive yellow-orange ridges in areal views due to their mechanically-resistant carbonate-silica mineralogy and iron oxidation. They form when an ultramafic protolith comes into contact with CO 2 -rich fluids and undergoes a progressive replacement of the Fe/Mg-bearing olivines and pyroxenes or serpentinites into increasingly carbonate-rich assemblages, and ultimately to carbonate-quartz rocks. We analyzed listvenite samples from the Atlin area, British Columbia, Canada using a variety of analytical techniques, including X-ray diffraction (XRD), X-ray fluorescence (XRF), wet chemistry (WC), visible-near infrared (VNIR) reflectance spectroscopy (0.35-2.5 μm), and Raman spectroscopy. VNIR and Raman spectroscopies were able to successfully identify all major mineral phases through their diagnostic absorption (VNIR) or emission (Raman) features. We found that listvenite composition is readily derivable from VNIR reflectance and Raman spectra, with fuchsite providing a diagnostic signature in VNIR spectra due to its unique Cr 3+ absorption bands that remain detectable even at low concentrations. These findings establish a spectroscopic framework for identifying listvenites in remote sensing applications, relevant for exploration of Solar System bodies, particularly Mars, where such carbonated ultramafic rocks can produce H 2 and CH 4 , and may preserve biosignatures and might indicate past habitable conditions associated with their low-temperature formation.