Mastcam mosaic from the sol 1686 rover location trying behind the rover (downslope) on the transition level between the Sutton Island and Blunts Level Murray members. Pictures from sols 1685–1689 show sedimentary textures of dark-toned Mn-rich sandstones and close by rocks. Dashed line packing containers within the giant mosaic are proven as insets alongside the underside of determine. Small crimson outlines present the approximate places and extent of ChemCam observations (parts of the Distant Micro Imager pictures of those observations are proven in Determine 3). All through this transition space, dark-toned sandstones (presumably Mn-rich primarily based on ChemCam observations at three places) overlie light-toned supplies. Insets from left to proper: (a) Denning Brook, a Mn-rich fine-grained dark-toned sandstone ChemCam commentary; (b) & (c) two light-toned blocks with cross-stratified textures, highlighted with yellow traces, 6 m away from Denning Brook and to the higher left within the giant mosaic; (d) dark-toned supplies (middle of mosaic); and E1) Newport Ledge, E2) AEGIS submit 1685a, E3) Sugarloaf Mountain, three skinny planar laminated dark-toned sandstones. NASA/Caltech-JPL/MSSS.
A analysis workforce utilizing the ChemCam instrument onboard NASA’s Curiosity rover found higher-than-usual quantities of manganese in lakebed rocks inside Gale Crater on Mars, which signifies that the sediments have been shaped in a river, delta, or close to the shoreline of an historical lake. The outcomes have been revealed at present in Journal of Geophysical Analysis: Planets.
“It’s tough for manganese oxide to type on the floor of Mars, so we didn’t look forward to finding it in such excessive concentrations in a shoreline deposit,” mentioned Patrick Gasda, of Los Alamos Nationwide Laboratory’s House Science and Functions group and lead writer on the examine. “On Earth, a majority of these deposits occur on a regular basis due to the excessive oxygen in our ambiance produced by photosynthetic life, and from microbes that assist catalyze these manganese oxidation reactions.
(a) The chemostratigraphic illustration is a document of the rover’s climb via the Bradbury, Mount Sharp, and Siccar Level Group (the stratigraphic column was ready by Mars Science Laboratory Sedimentology and Stratigraphy Working Group), specializing in the Murray formation under Vera Rubin ridge, with (b) MnO abundance versus elevation relative to imply Mars elevation. A plot increasing the vary of bedrock compositions (≤0.4 wt% MnO) is proven on the left, and the total vary of MnO (as much as 6 wt% MnO) is proven on the suitable. Calcium sulfate and high-silica diagenetic options have been eliminated. Main facies plotted: Murray bedrock (black), diagenetic options (white), diagenetic concretions (orange), dark-toned sandstones (magenta), and light-toned sandstones (pink). Each plots in panel (b) present the identical information. (c) The placement of Newport Ledge is labeled alongside the traverse and the pink arrow exhibits this location on the MnO versus. elevation plot. (d) The places with excessive manganese sandstones are proven on the traverse map with 1 m contour traces. The AEGIS submit drive targets listed in Desk 1 occurred on the corresponding labeled sol places — Journal of Geophysical Analysis: Planets
“On Mars, we don’t have proof for all times, and the mechanism to provide oxygen in Mars’s historical ambiance is unclear, so how the manganese oxide was shaped and concentrated right here is admittedly puzzling. These findings level to bigger processes occurring within the Martian ambiance or floor water and exhibits that extra work must be executed to know oxidation on Mars,” Gasda added.
ChemCam, which was developed at Los Alamos and CNES (the French area company), makes use of a laser to type a plasma on the floor of a rock, and collects that gentle as a way to quantify elemental composition in rocks.
(a, c–e) Pictures of dark-toned sandstones categorised by the GINI Index (Rivera-Hernández et al., 2019) as coarser grained. Yellow arrows level to particular person grains. Some grains in pictures are outlined with yellow dotted traces. Mars Hand Lens Imager (MAHLI) pictures (a)–(b) are proven on the identical 1 mm scale. Distant Micro Imager (RMI) pictures (c)–(e) are proven with the identical 5 mm scale. (a) MAHLI picture (cropped from full 15 mm standoff picture) of Newport Ledge show ∼0.1 mm darkish and light-weight toned grains (very positive to positive sand) inside a fine-grained matrix. Examine to (b) MAHLI of Cassongue goal, a typical Sutton Island Murray goal from decrease within the part (sol: 1482; elev: −4,367 m), a light-toned very positive grained materials with surficial regolith grains for comparability, and with widespread calcium sulfate veins. Grains usually are not discernible within the MAHLI picture of Cassongue; due to this fact, the rock is more likely to be very positive silt or mudstone. RMI pictures of AEGIS Put up 1685a (c), Newport Ledge (d), and Denning Brook (e) present grain sizes of as much as 0.25 mm (coarse silt to positive grained sandstone). Picture credit score: NASA/Caltech-JPL/MSSS.
The sedimentary rocks explored by the rover are a mixture of sands, silts, and muds. The sandy rocks are extra porous, and groundwater can extra simply move via sands in comparison with the muds that make up a lot of the lakebed rocks within the Gale Crater. The analysis workforce checked out how manganese may have been enriched in these sands—for instance, by percolation of groundwater via the sands on the shore of a lake or mouth of a delta—and what oxidant could possibly be liable for the precipitation of manganese within the rocks.
On Earth, manganese turns into enriched due to oxygen within the ambiance, and this course of is commonly sped up by the presence of microbes. Microbes on Earth can use the various oxidation states of manganese as power for metabolism; if life was current on historical Mars, the elevated quantities of manganese in these rocks alongside the lake shore would have been a useful power supply for all times.
“The Gale lake setting, as revealed by these historical rocks, provides us a window right into a liveable setting that appears surprisingly just like locations on Earth at present,” mentioned Nina Lanza, principal investigator for the ChemCam instrument. “Manganese minerals are widespread within the shallow, oxic waters discovered on lake shores on Earth, and it’s exceptional to seek out such recognizable options on historical Mars.”
Manganese-Wealthy Sandstones as an Indicator of Historic Oxic Lake Water Situations in Gale Crater, Mars, JGR planets (open entry)
Astrobiology
