TES and THEMIS study of proposed paleolake basins within the Aeolis quadrangle of Mars

Abstract

Several studies have described photogeologic evidence for paleolacustrine basins on Mars, mostly within impact craters. If these basins contained persistent standing water subsequently lost through evaporation, they may have contained deposits of evaporite minerals. If still present and sufficiently exposed, these evaporites would be detectable in orbital thermal infrared spectra. Using data from Mars Orbiter–Thermal Emission Imaging System (MO‐THEMIS) and Mars Global Surveyor–Thermal Emission Spectrometer (MGS‐TES), we examined proposed paleolake basins within Aeolis quadrangle, including Gusev and Gale craters. Gusev Crater is dominated by units with a spectrally intermediate to thick layer of dust mantling the surface. TES linear deconvolutions of the low‐albedo deposits, which have a thinner dust mantling, include Surface Type 1 (basalt) materials when sulfates are included in the end‐member library. Otherwise, the linear deconvolution uses Surface Type 2 (andesite or weathered basalt). THEMIS surface emissivity spectra for the low‐albedo deposits do not display sufficient contrast to distinguish between Surface Types. Gale Crater is relatively dust‐free, except for the mound variably covered in a spectrally intermediate to thick layer of dust. TES linear deconvolutions of crater floor and less dusty portion of the mound are consistent with a mixture of Surface Types 1 and 2. THEMIS surface emissivity spectra are consistent with Surface Type 1 or a mixture of Surface Types 1 and 2 for the crater floor and surface dust for the mound. These results do not discriminate between several previously suggested origins (fluvial‐lacustrine, aeolian, or volcanic deposition) for the mound layers. We find no spectral evidence for evaporite deposits that might substantiate paleolakes existed in these craters.