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JOURNAL OF GEOPHYSICAL RESEARCH,
VOL. 111,
E02S07,
27 PP., 2006
doi:10.1029/2005JE002503
Geology of the Gusev cratered plains from the Spirit rover transverse
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA
Smithsonian Institution, Washington, DC, USA
Department of Geological Sciences, Arizona State University, Tempe, Arizona, USA
NASA Ames Research Center, Moffett Field, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Department of Geological Sciences, Arizona State University, Tempe, Arizona, USA
Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri, USA
Department of Earth and Planetary Sciences, Washington University, St. Louis, Missouri, USA
Department of Geological Sciences, University of Tennessee, Knoxville, Tennessee, USA
Department of Geological Sciences, Arizona State University, Tempe, Arizona, USA
Department of Geological Sciences, Arizona State University, Tempe, Arizona, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Jet Propulsion Laboratory, California Institute of Technology, Pasadena, California, USA
Department of Civil and Environmental Engineering and Geodetic Science, Ohio State University, Columbus, Ohio, USA
Department of Astronomy, Cornell University, Ithaca, New York, USA
Department of Astronomy, Cornell University, Ithaca, New York, USA
The cratered plains of Gusev traversed by Spirit are generally low-relief rocky plains dominated by impact and eolian processes. Ubiquitous shallow, soil-filled, circular depressions, called hollows, are modified impact craters. Rocks are dark, fine-grained basalts, and the upper 10 m of the cratered plains appears to be an impact-generated regolith developed over intact basalt flows. Systematic field observations across the cratered plains identified vesicular clasts and rare scoria similar to original lava flow tops, consistent with an upper inflated surface of lava flows with adjacent collapse depressions. Crater and hollow morphometry are consistent with most being secondaries. The size-frequency distribution of rocks >0.1 m diameter generally follows exponential functions similar to other landing sites for total rock abundances of 5–35%. Systematic clast counts show that areas with higher rock abundance and more large rocks have higher thermal inertia. Plains with lower thermal inertia have fewer rocks and substantially more pebbles that are well sorted and evenly spaced, similar to a desert pavement or lag. Eolian bed forms (ripples and wind tails) have coarse surface lags, and many are dust covered and thus likely inactive. Deflation of the surface ∼5–25 cm likely exposed two-toned rocks and elevated ventifacts and transported fines into craters creating the hollows. This observed redistribution yields extremely slow average erosion rates of ∼0.03 nm/yr and argues for very little long-term net change of the surface and a dry and desiccating environment similar to today's since the Hesperian (or ∼3 Ga).
Received 27 May 2005; accepted 9 September 2005; published 12 January 2006.
Citation: (2006), Geology of the Gusev cratered plains from the Spirit rover transverse, J. Geophys. Res., 111, E02S07, doi:10.1029/2005JE002503.
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