Williams RME, Grotzinger JP, Dietrich WE, Gupta S, Sumner DY, Wiens RC, Mangold N, Malin MC, Edgett KS, Maurice S, Forni O, Gasnault O, Ollila A, Newsom HE, Dromart G, Palucis MC, Yingst RA, Anderson RB, Herkenhoff KE, Le Mouélic S, Goetz W, Madsen MB, Koefoed A, Jensen JK, Bridges JC, Schwenzer SP, Lewis KW, Stack KM, Rubin D, Kah LC, Bell JF, Farmer JD, Sullivan R, Van Beek T, Blaney DL, Pariser O, Deen RG. Martian fluvial conglomerates at Gale crater.
Science 2013;
340:1068-72. [PMID:
23723230 DOI:
10.1126/science.1237317]
[Citation(s) in RCA: 281] [Impact Index Per Article: 25.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Observations by the Mars Science Laboratory Mast Camera (Mastcam) in Gale crater reveal isolated outcrops of cemented pebbles (2 to 40 millimeters in diameter) and sand grains with textures typical of fluvial sedimentary conglomerates. Rounded pebbles in the conglomerates indicate substantial fluvial abrasion. ChemCam emission spectra at one outcrop show a predominantly feldspathic composition, consistent with minimal aqueous alteration of sediments. Sediment was mobilized in ancient water flows that likely exceeded the threshold conditions (depth 0.03 to 0.9 meter, average velocity 0.20 to 0.75 meter per second) required to transport the pebbles. Climate conditions at the time sediment was transported must have differed substantially from the cold, hyper-arid modern environment to permit aqueous flows across several kilometers.
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