Retrieval of Compositional End-Members From Mars Exploration Rover Opportunity Observations in a Soil-Filled Fracture in Marathon Valley, Endeavour Crater Rim
Abstract
The Opportunity rover investigated a gentle swale on the rim of Endeavour crater called Marathon Valley where a series of bright planar outcrops are cut into polygons by fractures. A wheel scuff performed on one of the soil-filled fracture zones revealed the presence of three end-members identified on the basis of Pancam multispectral imaging observations covering ~0.4 to 1 μm: red and dark pebbles, and a bright soil clod. Multiple overlapping Alpha Particle X-ray Spectrometer (APXS) measurements were collected on three targets within the scuff zone. The field of view of each APXS measurement contained various proportions of the Pancam-based end-members. Application of a log maximum likelihood method for retrieving the composition of the end-members using the 10 APXS measurements shows that the dark pebble end-member is compositionally similar to average Mars soil, with slightly elevated S and Fe. In contrast, the red pebble end-member exhibits enrichments in Al and Si and is depleted in Fe and Mg relative to average Mars soil. The soil clod end-member is enriched in Mg, S, and Ni. Thermodynamic modeling of the soil clod end-member composition indicates a dominance of sulfate minerals. We hypothesize that acidic fluids in fractures leached and oxidized the basaltic host rock, forming the red pebbles, and then evaporated to leave behind sulfate-cemented soil.
Additional Information
© 2017 American Geophysical Union. Received 3 MAY 2017; Accepted 19 DEC 2017; Accepted article online 29 DEC 2017; Published online 30 JAN 2018. We thank the Opportunity Project Team at the NASA/Caltech Jet Propulsion Laboratory who made possible the collection of data used in this paper. This material is based in part on a contract from Cornell University/NASA for participation in the Opportunity rover mission and is also partially supported by the National Science Foundation Graduate Research Fellowship under grant DGE-1144469. J. G. C. acknowledges support from the NASA Mars Fundamental Research program through grant NNX14AJ95G. The data used are listed in the tables and/or are archived in the Planetary Data System (pds.nasa.gov).Attached Files
Published - Stein_et_al-2018-Journal_of_Geophysical_Research__Planets.pdf
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Additional details
- Alternative title
- Retrieval of Compositional Endmembers from Mars Exploration Rover Opportunity Observations in a Soil-filled Fracture in Marathon Valley, Endeavour Crater Rim
- Eprint ID
- 84035
- Resolver ID
- CaltechAUTHORS:20180102-152036738
- DGE-1144469
- NSF Graduate Research Fellowship
- NNX14AJ95G
- NASA
- Created
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2018-01-02Created from EPrint's datestamp field
- Updated
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2023-04-13Created from EPrint's last_modified field