Abstract
Structure and stratigraphy of Home Plate from the Spirit Mars Exploration Rover
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, California, USA
Center for Radiophysics and Space Research, Cornell University, Ithaca, New York, USA
Center for Radiophysics and Space Research, Cornell University, Ithaca, New York, USA
New Mexico Museum of Natural History and Science, Albuquerque, New Mexico, USA
Department of Mineral Sciences, National Museum of Natural History, Smithsonian Institution, Washington, D. C., USA
Home Plate is a layered plateau observed by the Mars Exploration Rover Spirit in the Columbia Hills of Gusev Crater. The structure is roughly 80 m in diameter, and the raised margin exposes a stratigraphic section roughly 1.5 m in thickness. Previous work has proposed a pyroclastic surge, possibly followed by aeolian reworking of the ash, for the depositional origin for these beds. We have performed a quantitative analysis of the structure, stratigraphy, and sedimentology at this location. Our results are consistent with an explosive volcaniclastic origin for the layered sediments. Analysis of bedding orientations over half of the circumference of Home Plate reveals a radially inward dipping structure, consistent with deposition in the volcanic vent, or topographic draping of a preexisting depression. Detailed observations of the sedimentology show that grain sorting varies significantly between outcrops on the east and west sides. Observations on the western side show a well-sorted population of sand sized grains which comprise the bedrock, while the eastern margin shows a wider range of grain sizes, including some coarse granules. These observations are consistent with primary deposition by a pyroclastic surge. However, aeolian reworking of the upper stratigraphic unit is not ruled out. Identification of explosive volcanic products on Mars may implicate magma interaction with subsurface hydrologic reservoirs in the past.
Received 19 October 2007; accepted 14 August 2008; published 13 November 2008.
Citation: (2008), Structure and stratigraphy of Home Plate from the Spirit Mars Exploration Rover, J. Geophys. Res., 113, E12S36, doi:10.1029/2007JE003025.
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