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脑纹地形

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脑纹地形(Brain terrain)也被称为脑珊瑚结(Knobs-brain coral)和脑珊瑚地形(brain coral terrain),是在火星舌状岩屑坡线状谷底沉积同心坑沉积表面发现的,由复杂的垄脊所组成的一种地貌特征。由于外观酷似人脑表面的脑纹,所以被命名为脑纹地形,其中宽脊被称为“细胞闭合型”脑纹地形,而不太常见的窄脊则被称为“细胞开放型”脑纹地形[1]

据认为,宽脊的细胞闭合型地形中包裹着冰核,一旦冰核融化消失时,宽脊中心就会塌陷,形成开放细胞型的窄脊。来自高分辨率成像科学设备的阴影测量显示,这些垄脊有4-5米高[1]。脑纹地形被观察到由所谓的“平原上部单元”构成,这一过程起始于应力产生的裂纹,而平原上部单元则是累积的降雪和冰核尘埃覆盖层[2]

如今,人们普遍认可如舌状岩屑坡线状谷底沉积同心坑沉积等类冰川结构都是相互关联的,因为它们具有相同的表面结构。峡谷中冰川类结构和冰斗状的凹壁可能会与其他类型的因素结合,形成舌状岩屑坡。当相向的舌状岩屑坡汇聚时,就会产生出线状谷底沉积[3],它们可能都富含水冰物质。 在北半球火星分界线附近区域发现了很多此类特征,大部分位于东经0度至70度之间[4],该区域附近的地区被用一些古地名命名:都特罗尼勒斯桌山群普罗敦尼勒斯桌山群尼罗瑟提斯桌山群。舌状岩屑坡、线状谷底沉积和同心坑沉积中可能有大量被尘土和岩屑覆盖的积冰[5][6][7][8]

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参考文献

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  1. ^ 1.0 1.1 Levy, J., J. Head, D. Marchant. 2009. Concentric crater fill in Utopia Planitia: History and interaction between glacial “brain terrain” and periglacial mantle processes. Icarus 202, 462–476.
  2. ^ Baker, D., J. Head. 2015. Extensive Middle Amazonian mantling of debris aprons and plains in Deuteronilus Mensae, Mars: Implication for the record of mid-latitude glaciation. Icarus: 260, 269-288.
  3. ^ Souness, C. and B. Hubbard.  2013. An alternative interpretation of late Amazonian ice flow: Protonilus Mensae, Mars. Icarus 225, 495-505.
  4. ^ Barlow, N. 2008. Mars: An Introduction to its Interior, Surface and Atmosphere. Cambridge University Press. ISBN 978-0-521-85226-5
  5. ^ Head, J. and D. Marchant. 2006. Evidence for global-scale northern mid-latitude glaciation in the Amazonian period of Mars: Debris-covered glacial and valley glacial deposits in the 30 - 50 N latitude band. Lunar. Planet. Sci. 37. Abstract 1127
  6. ^ Head, J. and D. Marchant. 2006. Modifications of the walls of a Noachian crater in Northern Arabia Terra (24 E, 39 N) during northern mid-latitude Amazonian glacial epochs on Mars: Nature and evolution of Lobate Debris Aprons and their relationships to lineated valley fill and glacial systems. Lunar. Planet. Sci. 37. Abstract 1128
  7. ^ Head, J., et al. 2006. Extensive valley glacier deposits in the northern mid-latitudes of Mars: Evidence for the late Amazonian obliquity-driven climate change. Earth Planet. Sci. Lett. 241. 663-671
  8. ^ Head, J., et al. 2006. Modification if the dichotomy boundary on Mars by Amazonian mid-latitude regional glaciation. Geophys. Res Lett. 33