Other
Scientific paper
Dec 2011
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2011agufm.p31g..01y&link_type=abstract
American Geophysical Union, Fall Meeting 2011, abstract #P31G-01
Other
[1034] Geochemistry / Hydrothermal Systems, [5470] Planetary Sciences: Solid Surface Planets / Surface Materials And Properties, [6225] Planetary Sciences: Solar System Objects / Mars
Scientific paper
The Spirit rover ended its science mission on the martian surface after operating for 2210 sols and covering over 7.7 km across geologically diverse terrain. A multitude of discoveries have been made along the traverse, including compelling evidence for past hydrothermal activity at the surface of Mars. Several light-toned deposits excavated by the rover wheels were analyzed in detail by the Mössbauer and Alpha Particle X-ray Spectrometers (APXS), which determined that they are dominated by ferric sulfates in association with magnesium sulfates, silica and occasionally calcium sulfates and phosphates. Based on modeling of scatter peaks within the APXS data, these samples are hydrated and contain up to 18 wt% water. They also exhibit the chemical signatures of nearby rocks (e.g. corresponding phosphate enrichments) and have a Fe:Mn ratio far from the value measured for the majority of samples analyzed by the rovers, clearly indicative of aqueous interactions. Variability in the deposits over centimeter to meter scales indicates that these precipitates did not develop under large-scale equilibrium conditions. Based upon the observations of up to 35 wt% SO3 and the abundance of measured cations in expected oxidation states, the occurrence of elemental sulfur, sulfuric acid, or sulfides cannot be ruled out. The likely mechanisms for the formation of these deposits involve sulfur-rich hydrothermal fluids and volcanic vapors reaching the surface and producing fumarolic condensates. In close association with the samples containing abundant hydrated ferric sulfates are other samples which are dominated by silica. In one example, the elemental chemistry data shows over 90 wt% SiO2. Elevated titanium concentrations in these silica-rich samples are suggestive of interactions with acidic fluids or vapors resulting in preferential retention of the least mobile elements. This is consistent with the acid sulfate processes indicated by the occurrence of the ferric sulfates. Volcanic emissions are commonly enriched in zinc, and the highest concentrations of this element measured by Spirit (0.1 to 0.2 wt%) are in close proximity to the silica and ferric sulfate-rich samples. Nickel, another volcanic volatile, is also enriched in the high-Zn samples. Furthermore, the measured Zn:Cl ratio in this series of analyses is indicative of a high-temperature process. Taken collectively, these observations clearly indicate the discovery of a hydrothermal region at the martian surface. While many of these deposits are concentrated near "Home Plate" (a ~90 meter diameter, light-toned feature visible from orbit), other known occurrences are over 1 km away at elevations varying by several tens of meters. These deposits are likely far more widespread than the specific locations uncovered by the Spirit rover, and they are not constrained by the geologic setting to be ancient. They could, in fact, be remnants of relatively recent hydrothermal activity.
Athena Science Team
Clark Ben C.
Gellert Ralf
Morris Richard V.
Yen Albert S.
No associations
LandOfFree
Clear Evidence for Hydrothermal Deposits within Gusev Crater Established by the Mars Exploration Rover Spirit does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Clear Evidence for Hydrothermal Deposits within Gusev Crater Established by the Mars Exploration Rover Spirit, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Clear Evidence for Hydrothermal Deposits within Gusev Crater Established by the Mars Exploration Rover Spirit will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-870515