Windblown Basaltic Sands on the Northern Slopes of Mount Sharp and Adjacent Plains, Gale Crater, Mars

Abstract:

Using a new method to retrieve thermal inertia (TI) values at 18 m/pixel that employs Mars Reconnaissance Orbiter (MRO) CRISM long wavelength spectral data (mix of solar reflectance and thermal emission terms) we have explored relationships between retrieved TI values, CRISM-based spectral reflectance data, and a HiRISE-based distribution of modern sand deposits and bedrock. We find a strong inverse correlation between TI values and spectral parameters indicative of the areal abundance of ferrous silicates (i.e., olivine and pyroxene). The Curiosity rover has traversed from the Bradbury landing site on the plains to the north of Mount Sharp, to Glen Torridon and the Greenheugh pediment on the northern slopes of Mount Sharp. The inverse relationship accounts for the vast majority of the fractional variance for both linear and polynomial least squares fits predicting ferrous silicate detection values as a function of TI values along and near the traverses. The high ferrous silicate, low TI endmember in the inverse trend is associated with the longitudinal component of the Bagnold dunes. The low ferrous silicate, high TI endmember occurs on the plains far from windblown sands dispersed from the dunes. This correlation indicates that sands dispersed from the dunes provide a sand cover that thins as the distance from the dunes increases, with values close to the dunes controlling both the thermal skin depth and ferrous silicate signature.