Characteristics, distribution, origin, and significance of opaline silica observed by the Spirit rover in Gusev crater, Mars
Article first published online: 22 APR 2011
Copyright 2011 by the American Geophysical Union.
Journal of Geophysical Research: Planets (1991–2012)
Volume 116, Issue E7, July 2011
How to Cite
2011), Characteristics, distribution, origin, and significance of opaline silica observed by the Spirit rover in Gusev crater, Mars, J. Geophys. Res., 116, E00F23, doi:10.1029/2010JE003767., et al. (
- Issue published online: 22 APR 2011
- Article first published online: 22 APR 2011
- Manuscript Accepted: 4 FEB 2011
- Manuscript Revised: 19 JAN 2011
- Manuscript Received: 27 OCT 2010
- Gusev crater;
 The presence of outcrops and soil (regolith) rich in opaline silica (∼65–92 wt % SiO2) in association with volcanic materials adjacent to the “Home Plate” feature in Gusev crater is evidence for hydrothermal conditions. The Spirit rover has supplied a diverse set of observations that are used here to better understand the formation of silica and the activity, abundance, and fate of water in the first hydrothermal system to be explored in situ on Mars. We apply spectral, chemical, morphological, textural, and stratigraphic observations to assess whether the silica was produced by acid sulfate leaching of precursor rocks, by precipitation from silica-rich solutions, or by some combination. The apparent lack of S enrichment and the relatively low oxidation state of the Home Plate silica-rich materials appear inconsistent with the originally proposed Hawaiian analog for fumarolic acid sulfate leaching. The stratiform distribution of the silica-rich outcrops and their porous and brecciated microtextures are consistent with sinter produced by silica precipitation. There is no evidence for crystalline quartz phases among the silica occurrences, an indication of the lack of diagenetic maturation following the production of the amorphous opaline phase.