Open AccessCopahue volcano: A modern terrestrial analog for the opportunity landing site?
Author(s) -
Varekamp Johan C.
Publication year - 2004
Publication title -
eos, transactions american geophysical union
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.316
H-Index - 86
eISSN - 2324-9250
pISSN - 0096-3941
DOI - 10.1029/2004eo410002
Subject(s) - jarosite , gypsum , geology , alunite , anhydrite , hematite , geochemistry , volcano , impact crater , mars exploration program , mineralogy , sulfate , pyrite , earth science , astrobiology , chemistry , paleontology , physics , organic chemistry , hydrothermal circulation
The Opportunity Rover on Mars landed in an environment that contained grey hematite (specularite) and jarosite,with structures indicative of flowing water. Less firm evidence suggests the presence of gypsum as well, and the environment is overall rich in S, Cl, and Br (NASA news releases, 2004). Such a suite of minerals may form from an iron‐ and sulfate‐rich brine, either through evaporation, cooling, or changes in redox conditions (see Hynek et al. [2002] and Christensen et al. [2001], for a discussion of the extent and possible origins of the Mars hematite deposits). On Earth, such an association of minerals is not very common, but is found in alteration zones with fumarolic activity in some volcanic craters. The condensation or dissolution in meteoric waters of S‐rich volcanic gases creates acid fluids in the surficial environment that leach rock‐forming elements (RFEs) from the surrounding rocks, forming large, bleached areas of mineralizations of hematite, cristobalite, and gypsum, occasionally with zones rich in alunite or jarosite.