同心坑沉積(concentric crater fill)是指撞擊坑坑底大部分地區綿延着許多道平行山脊的地形地貌[1],這種類型的撞擊坑在火星中緯度地區很常見[2][3],並普遍認為是冰川運動所造成的[4][5]。火星上被稱為都特羅尼勒斯桌山群普羅敦尼勒斯桌山群的地區都分佈着許多同心坑沉積。

說明

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同心坑沉積,與舌狀岩屑坡線狀谷底沉積一樣,被認為都富含水冰[6],有時在同心坑沉積上發現的巨礫,據認為它們是從撞擊坑坑壁上剝落的,然後隨着冰川的運動而被移離[7][8],地球上的漂礫也以類似的方法被移動。

高解像度成像科學設備(HiRISE)拍攝的高清照片顯示,同心坑沉積的部分表面覆蓋了一層被稱為細胞閉合型和細胞開放型腦紋地形的奇特圖案。這種地形類似人腦,據信這是由於堆積的灰塵及其他碎屑的表面裂縫以及部分表面冰升華所致,而產生裂縫的原因則是重力和季節性冷熱二種因素共同作用的結果[9][10]

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參考文獻

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  1. ^ Archived copy. [2010-08-01]. (原始內容存檔於2016-10-01). 
  2. ^ Dickson, J. et al.  2009.  Kilometer-thick ice accumulation and glaciation in the northern mid-latitudes of Mars:  Evidence for crater-filling events in the Late Amazonian at the Phlegra Montes.  Earth and Planetary Science Letters.
  3. ^ HiRISE - Concentric Crater Fill in the Northern Plains (PSP_001926_2185). hirise.lpl.arizona.edu. [2020-11-03]. (原始內容存檔於2020-08-01). 
  4. ^ Head, J. et al.  2006.  Extensive valley glacier deposits in the northern mid-latitudes of Mars:  Evidence for late Amazonian obliquity-driven climate change.  Earth Planet. Sci Lett: 241.  663-671.
  5. ^ Levy, J. et al.  2007.  Lineated valley fill and lobate debris apron stratigraphy in Nilosyrtis Mensae, Mars:  Evidence for phases of glacial modification of the dichotomy boundary.  J. Geophys. Res.:  112.
  6. ^ Levy, J. et al.  2009.  Concentric crater fill in Utopia Planitia:  History and interaction between glacial "brain terrain" and periglacial processes.  Icarus: 202. 462-476.
  7. ^ Marchant, D. et al.  2002.  Formation of patterned ground and sublimation till over Miocene glacier ice in Beacon valley, southern Victorialand, Antarctica.  Geol. Soc. Am. Bull:114.  718-730.
  8. ^ Head, J. and D. Marchant.  2006.  Modification of the walls of a Noachian crater in northern Arabia Terra (24E, 39N) during 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 # 1126.
  9. ^ Mellon, M.  1997.  Small-scale polygonal features on Mars:  Seasonal thermal contraction cracks in permafrost.  J. Geophysical Res: 102. 25,617-625,628.
  10. ^ Ley, J. et al.  2009.  Concentric crater fill in Utopia Planitia:  History and interaction between glacial "brain terrain" and periglacial processes.  Icarus: 202.  462-476.