Infrared spectroscopy of weathering products in a terrestrial glacial environment: Implications for cold weathering on planetary surfaces

Geologic features on Mars show evidence of modification by water and water ice. Past obliquity variations are hypothesized to have allowed the formation and stability of ground ice near the equator, possibly promoting the accumulation of glaciers. Massive ice deposits, including probable glacial and periglacial features have also been observed in the east Hellas Basin and Deuteronilus Mensae regions, located at the midlatitudes of Mars. These features indicate present-day, near-surface ice has been in contact with geologic materials, creating an environment in which cold weathering processes could have been occurring, and might still be at work. Weathering processes in cold terrestrial environments are not well understood, and processes acting on subglacial and englacial sediments and rocks are not well characterized due to the remote location of many glaciers and the difficulty of collecting samples. The types of weathering products and energy sources produced in a glacial environment will drive the overall energy budget for any microbial communities present. The subglacial energy budget for microbes thus has implications in the search for life on other planets, making glacial and periglacial terrains excellent sites for future exploration. However, planetary ice deposits are difficult to study due to their sensitive nature and are thus limited to observation from orbit at present. It is therefore a key concern to better understand the types materials and alteration products that can be observed and constrained from orbital data. In this study, we characterize the types of weathering products present in a glacial system using ground-truthed remote sensing techniques. Robertson Glacier, Alberta, Canada (115°20'W, 50°44'N) provides an excellent testbed for this technique as it is accessible, and its recent and continuing retreat allows fresh subglacial and englacial sediments to be sampled. Samples of bedrock and glacially altered rock and sediments were collected from Robertson Glacier. Infrared laboratory spectra of these samples were collected and used to determine the composition and abundance of minerals in rock and sediment samples, with a primary focus on differentiating weathering products. These spectra were then correlated to multispectral images taken by the Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) satellite instrument. Initial results from both laboratory and ASTER data indicate the presence of weathering products. Laboratory spectra of field samples are promising in that major bedrock mineral assemblages and a variety of alteration products can be identified. However, more mineralogical work is required to refine the types of weathering products present in the system.