Squyres SW, Arvidson RE, Bell III JF, Calef III FJ, Cohen BA, Clark BC, Crumpler LS, Farrand WH, Gellert R, Grant JA, Herkenhoff KE, Hurowitz JA, Johnson JR & Schröder C (2012) Ancient Impact and Aqueous Processes at Endeavour Crater, Mars. Science, 336 (6081), pp. 570-576. https://doi.org/10.1126/science.1220476
The rover Opportunity has investigated the rim of Endeavour Crater, a large ancient impact crater on Mars. Basaltic breccias produced by the impact form the rim deposits, with stratigraphy similar to that observed at similar-sized craters on Earth. Highly localized zinc enrichments in some breccia materials suggest hydrothermal alteration of rim deposits. Gypsum-rich veins cut sedimentary rocks adjacent to the crater rim. The gypsum was precipitated from low-temperature aqueous fluids flowing upward from the ancient materials of the rim, leading temporarily to potentially habitable conditions and providing some of the waters involved in formation of the ubiquitous sulfate-rich sandstones of the Meridiani region.
Additional co-authors: BL Jolliff, AH Knoll, R Li, SM McLennan, DW Ming, DW Mittlefehldt, TJ Parker, G Paulsen, MS Rice, SW Ruff, AS Yen, K Zacny
Science: Volume 336, Issue 6081