CRISM GLOBAL MAPPING: A KEY TOOL FOR ASSESSING GEOLOGIC SETTINGS OF MARTIAN SULFATE MINERALS

In addition to collecting high spectral- and spatial-resolution "targeted" observations, the Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) on the Mars Reconnaissance Orbiter (MRO) conducted several global mapping campaigns over multiple Mars years to acquire data that are at reduced spatial resolution but at comparable to or better resolution than other global spectral data sets. Two of the campaigns have been processed into tiled, map-projected products of particular value for understanding the stratigraphic and geologic settings and mineral associations of sulfate minerals. One set of products ("MRDRs") is a VNIR-IR multispectral map (72 channels from 0.4-3.9 µm, sampled at 180 m/pixel) with wavelengths chosen to measure the spectral absorptions of key minerals, including mafic and ferric minerals as well as hydrated / hydroxylated silicates and sulfates. The second product ("VRDRs") is a VNIR hyperspectral map (90 channels from 0.4-1.0 µm, sampled at 90 m/pixel) that provides improved resolution and more complete spectral and spatial coverage of iron-bearing mafic minerals as well as ferric mineralogies that are commonly associate with sulfates. Both data sets have been constructed using a multi-step pipeline (Seelos et al., Icarus, 115612) that remediates artifacts in the data and normalizes the tens of thousands of constituent observations to common illumination and observing conditions and atmospheric opacity. Most published studies of sulfate deposits using CRISM data focus on the targeted observations which are higher in spatial resolution but only cover a few percent of the Martian surface; relatively few studies (e.g., Cartwright et al., JGR Planets, 128, e2023JE008044) have yet made extensive use of the mapping data for scientific investigations. Here we provide an overview of CRISM mapping data products and their coverage of sulfate-bearing deposits, review key science questions that are addressed by the data, summarize early results using the data to map occurrences of different sulfate phases, and explore representative locations which document geologic and mineralogic associations of sulfate-rich Martian deposits.