The Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) instrument on the Mars Reconnaissance Orbiter collected data in a spatially overlapping mode that show hematite, an iron oxide mineral, is present on the top of a layered ridge located about 3 km away from the Curiosity rover's proposed arrival point at Mount Sharp's base. The hematite formed either through leaching of local material in neutral to acidic waters or through mixing of anoxic groundwaters with a more oxidizing water body or atmosphere. These formation hypotheses can be tested using Curiosity's payload, and both scenarios indicate that the ridge was a site of past active iron oxidation. In similar environments on Earth, iron oxidation is almost exclusively mediated by microorganisms. This hematite ridge therefore represents a specific site where concentrated and localized iron oxidation occurred, and is a prime location to search for signs of past habitability.
Dynamic pore-pressure variations induce substrate erosion by pyroclastic flows
O. Roche et al., Laboratoire Magmas et Volcans, Universit Blaise Pascal, CNRS UMR6524, IRD R163, 5 rue Kessler, F-63038 Clermont-Ferrand, France. Published online ahead of print 30 July 2013, http://dx.doi.org/10.1130/G34668.1.
Pyroclastic flows are ground-hugging dense mixtures of gas and particles generated during volcanic eruptions. Field evidence shows that they can entrain blocks from underlying substrates formed by earlier geological events, yet, counter-intuitively, they are less likely to erode unconsolidated layers of fine particles. O. Roche and colleagues rep
|Contact: Kea Giles|
Geological Society of America