Evidence for impact-induced hydrothermal clay mineral formation at Endeavour crater, Mars.

摘要

Over 13 years after landing at Meridiani Planum and in her 10th extended mission, Mars Exploration Rover Opportunity continues to explore the rim of ~22 km diameter Endeavour crater. The rim exposes material that is older than the S-rich, layered sedimentary rock covering the Meridiani plains and filling much of the interior of Endeavour. Clay mineral exposures at the rim have been observed from orbit and confirmed on the ground. Clay minerals are thought to indicate wet, generally habitable environmental conditions more suitable to life than the S-rich, acidic waters responsible for the Meridiani sedimentary rocks. However, in order to assess the habitability of the past environment recorded by the Endeavour rim rocks it is important to understand how the clay minerals formed. Do they represent the conditions prior to impact; or do they result from impact-induced hydrothermal activity; or both? Here we present evidence that at least some of the observed clay mineral assemblages formed as a result of impact-induced hydrothermal alteration.