Martian Fluvial Conglomerates at Gale Crater-猫眼课题宝

DOI：

10.1126/science.1237317

发表时间：

2013-05

期刊：

Science

影响因子：

56.9

通讯作者：

中科院分区：

综合性期刊1区

文献类型：

作者：

Rebecca M. E. Williams;J. Grotzinger;W. Dietrich;Sanjeev Gupta;D. Sumner;R. Wiens;N. Mangold;M. Malin;K. Edgett;S. Maurice;O. Forni;O. Gasnault;A. Ollila;H. Newsom;G. Dromart;M. Palucis;R. Yingst;R. Anderson;K. Herkenhoff;S. Mouélic;W. Goetz;M. Madsen;A. Koefoed;J. Jensen;J. Bridges;S. Schwenzer;K. Lewis;K. Stack;D. Rubin;Linda C. Kah;J. Bell;J. Farmer;R. Sullivan;T. V. Beek;D. Blaney;O. Pariser;R. Deen

搭载好奇号火星车的火星科学实验室航天器于2011年11月从地球发射，并于2012年8月抵达火星上的盖尔陨石坑。Zeitlin等人（p. 1080）报告了航天器在火星巡航期间内部高能粒子辐射环境的测量结果，证实了这种辐射可能对未来可能前往火星的宇航员造成的危害。Williams等人（第1068页，参见Jerolmack的观点）报告了在Gale陨石坑发现的沉积砾岩（鹅卵石与沙子混合并变成岩石）。岩石的圆形表明鹅卵石在被水流从源头运送到几公里或更远的地方时受到了磨损。“好奇号”火星车对沉积岩中圆形鹅卵石的观测证实，火星上古代有水流。火星科学实验室桅杆照相机（Mastcam）在盖尔陨石坑的观测显示，有胶结卵石（直径2至40毫米）和沙粒的孤立露头，具有典型的河流沉积砾岩的纹理。砾岩中的圆形鹅卵石表明有大量的河流磨损。其中一个露头的化学cam发射光谱显示主要是长石成分，与沉积物的最小水蚀变相一致。泥沙在古代水流中被调动，可能超过了搬运鹅卵石所需的阈值条件（深度0.03至0.9米，平均流速0.20至0.75米/秒）。沉积物运输时的气候条件一定与寒冷、极度干旱的现代环境有很大的不同，才能使水流动跨越几公里。

Going to Mars The Mars Science Laboratory spacecraft containing the Curiosity rover, was launched from Earth in November 2011 and arrived at Gale crater on Mars in August 2012. Zeitlin et al. (p. 1080) report measurements of the energetic particle radiation environment inside the spacecraft during its cruise to Mars, confirming the hazard likely to be posed by this radiation to astronauts on a future potential trip to Mars. Williams et al. (p. 1068, see the Perspective by Jerolmack) report the detection of sedimentary conglomerates (pebbles mixed with sand and turned to rock) at Gale crater. The rounding of the rocks suggests abrasion of the pebbles as they were transported by flowing water several kilometers or more from their source. Observations from the Curiosity rover of rounded pebbles in sedimentary rocks confirm ancient water flows on Mars. [Also see Perspective by Jerolmack] 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.

Martian Fluvial Conglomerates at Gale Crater

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