Altered Basalts from Hawaii as an Analog for Alteration on Mars

Abstract

Mars has been a focus of planetary academic research for decades due to relatively new data from spacecraft. Spectral data from both satellite and rover instrumentation have provided identification of a variety of materials. Satellite data have guided future mission plans and deployments by providing coarsely defined areas of interest for up close observation. Recently, spectral data acquired by the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) have identified hydrated silicates, carbonates, and serpentines in multiple locations. All of these minerals provide evidence for occurrence of specific surface and crustal processes, many of which can produce habitable environments for simple life. Similar alteration minerals are present in basalt flows from Hawaii in a similar background lithology and present a prime analog for in-depth laboratory study to understand the processes resulting in alteration on Mars. Reflectance spectroscopy can identify minerals by quantifying how light of various wavelengths reflects from mineral crystals. Alteration minerals are generated from secondary processes after a rock forms, and many have particularly distinctive spectral signatures in the visible to short-wave infrared (VIS-SWIR) wavelengths. Past spectral work has already shown significant evidence of the presence of aqueous activity and associated alteration on Mars (Bibring et al., 2006: Milliken et al., 2008: Ehlmann et al, 2009: Ehlmann, Mustard, & Murchie, 2010). Less defined, however, is the genetic source of these alteration minerals. Finding out whether these minerals formed simply as a past product of surface water interaction with exposed basalt, or represent outcrops of alteration due to groundwater or subsurface water-rock interactions offers answers to significant scientific questions related to the planet. Also of interest is past (or possibly present) serpentinization, which (when active) produces magnetite and H2, a possible energy source for aqueous microbi