Details

Autor(en) / Beteiligte

• Cousin, A.
• Meslin, P.Y.
• Wiens, R.C.
• Rapin, W.
• Mangold, N.
• Fabre, C.
• Gasnault, O.
• Forni, O.
• Tokar, R.
• Ollila, A.
• Schröder, S.
• Lasue, J.
• Maurice, S.
• Sautter, V.
• Newsom, H.
• Vaniman, D.
• Le Mouélic, S.
• Dyar, D.
• Berger, G.
• Blaney, D.
• Nachon, M.
• Dromart, G.
• Lanza, N.
• Clark, B.
• Clegg, S.
• Goetz, W.
• Berger, J.
• Barraclough, B.
• Delapp, D.

Titel

Compositions of coarse and fine particles in martian soils at gale: A window into the production of soils

Ist Teil von

• Icarus (New York, N.Y. 1962), 2015-03, Vol.249, p.22-42

Ort / Verlag

Elsevier Inc

Erscheinungsjahr

2015

Link zum Volltext

Quelle

Elsevier ScienceDirect Journals Complete

Beschreibungen/Notizen

• •Martian soils are analyzed for the first time at sub millimeter scale.•Three different groups of coarse grains have been distinguished.•Fine particles seem to derive from one group of coarse grains.•Presence of amorphous component in fine particles and some coarse grains.•Fine particles have undergone limited interaction with water. The ChemCam instrument onboard the Curiosity rover provides for the first time an opportunity to study martian soils at a sub-millimeter resolution. In this work, we analyzed 24 soil targets probed by ChemCam during the first 250sols on Mars. Using the depth profile capability of the ChemCam LIBS (Laser-Induced Breakdown Spectroscopy) technique, we found that 45% of the soils contained coarse grains (>500μm). Three distinct clusters have been detected: Cluster 1 shows a low SiO2 content; Cluster 2 corresponds to coarse grains with a felsic composition, whereas Cluster 3 presents a typical basaltic composition. Coarse grains from Cluster 2 have been mostly observed exposed in the vicinity of the landing site, whereas coarse grains from Clusters 1 and 3 have been detected mostly buried, and were found all along the rover traverse. The possible origin of these coarse grains was investigated. Felsic (Cluster 2) coarse grains have the same origin as the felsic rocks encountered near the landing site, whereas the origin of the coarse grains from Clusters 1 and 3 seems to be more global. Fine-grained soils (particle size<laser beam diameter which is between 300 and 500μm) show a homogeneous composition all along the traverse, different from the composition of the rocks encountered at Gale. Although they contain a certain amount of hydrated amorphous component depleted in SiO2, possibly present as a surface coating, their overall chemical homogeneity and their close-to-basaltic composition suggest limited, or isochemical alteration, and a limited interaction with liquid water. Fine particles and coarse grains from Cluster 1 have a similar composition, and the former could derive from weathering of the latter. Overall martian soils have a bulk composition between that of fine particles and coarse grains. This work shows that the ChemCam instrument provides a means to study the variability of soil composition at a scale not achievable by bulk chemical analyses.