GEOLOGIC INTERPRETATION OF DATA SETS COLLECTED BY PLANETARY ANALOG GEOLOGY TRAVERSES AND BY STANDARD GEOLOGIC FIELD MAPPING: A COMPARISON STUDY (PART 2)

Though terrestrial geologic mapping techniques can be confidently applied to other planetary bodies, such application is complicated by the diverse type, areal coverage, and spatial resolution of remotely acquired data sets. Where available, spatially-limited in situ human and robotic surface observations can complicate geologic interpretation as much as they can assist. We compare two 1:24,000 scale geologic maps of the San Francisco Volcanic Field (SFVF), north-central Arizona that were constructed using 1) traditional field mapping techniques, and 2) remote data sets, augmented with limited field observations collected during NASA Desert Research & Technology Studies (RATS) 2010 exercises. Mapping for both approaches was based on several questions: 1) How many lava flow units are present, 2) How many vent structures are present, and 3) What is the nature of loosely consolidated surficial units? Generally, RATS sample stations enabled comparable characterization of different lava and vent units. Improved understanding of the volcanic units requires instrument suites that provide rapid and regular mineralogy/geochemistry information, or details related to subsurface structure. The latter question is highly relevant to extraterrestrial photogeologic mapping because dispersed sediments are frequently grouped into a single unit (e.g., “plains” material) and treated as obscuring units with little geologic information. However, field observation shows surficial units provide subtle but compelling geologic details. In SFVF, surficial unit(s) holds clues about the local to regional eruptive history. The continuous ability to observe/discuss surficial units among the terrestrial field team provided a more robust understanding of possible ash-, aeolian-, and fluvial/aeolian- dominated processes. During human missions to other planets instrument suites and/or approaches should provide rapid, regular observations of surfical units to best mimic the advantages of field based mapping approaches. Geologic maps of planetary bodies based primarily on remote based observations should cartographically represent – where possible – the components and gradational nature of surficial units. These subtle variations can provide critical insights into local to regional geologic formative histories.