尼罗瑟提斯桌山群

尼罗瑟提斯桌山群(Nilosyrtis Mensae)位于火星卡西乌斯区,其中心坐标为北纬36.87°、东经67.9°,它的东西经度分别为74.4°E和 51.1°E;南北纬度分别是 29.61°N和 36.87°N[2][2]。尼罗瑟提斯桌山群正对着西面的普罗敦尼勒斯桌山群,二者都坐落在火星分界线上。该桌山群纵横约705公里(438英里),取名自火星古典反照率特征,1973年被国际天文联合会正式接受。

尼罗瑟提斯桌山群
阿斯塔普斯小丘群中的山冈和凸岩
坐标36°52′N 67°54′E / 36.87°N 67.9°E / 36.87; 67.9
反转坑桌山,尼罗瑟提斯桌山群,它被认为是一座被侵蚀、填充的古老撞击坑,后来再次被侵蚀,所以现在成为一座四面绝壁的低矮平顶山。图像宽约900米。
尼罗瑟提斯桌山群中的基岩,该照片宽约1.5公里。在这幅色彩增强图像中,蓝色和绿色通常为铁镁质(富含)矿物,它们不会被水改变,而暖色部分则是因像粘土类的蚀变矿物造成的。这个地区的构造很复杂,受到过撞击,可能还有河流和火山活动、构造作用以及侵蚀,这是一处有着复杂地质史的古老地形[1]

尼罗瑟提斯桌山群的表面被归属为锐蚀地形(Fretted Terrain)。这里有悬崖、台地和宽阔平坦的山谷,其表面地貌被认为是由岩屑覆盖的冰川所造成[3][4]。这些围绕着丘群和桌山的冰川,被称为舌状岩屑坡[5][6][7][8];当冰川位于山谷中时,又被称为线状谷底沉积[9][10][11][12]。  

气候变化导致的富冰特征

几十年来,火星上的许多地貌特征,包括尼罗瑟提斯桌山群,都被认为含有大量的冰。这一想法被火星勘测轨道飞行器上的浅层雷达(SHARAD)所证实,勘测结果表明,舌状岩屑坡(LDA)和线状山谷沉积(LVF)都含有纯净水冰,上面覆盖着一层隔温的薄岩层 [13][14]。在北半球包括尼罗瑟提斯桌山群在内的许多地方都发现了冰[15]

关于冰的起源,最流行的模型是火星自转轴倾角的巨幅变化所引起的气候改变,有时倾斜角甚至超过80度[16][17],巨大的倾斜变化解释了为何火星上有许多富含冰的特征。

研究表明,当火星的倾角从目前的25度倾斜到45度时,两极的冰就不再稳定[18],此外,在这一高倾角时,固体的二氧化碳(干冰)就会升华,从而增加了大气压力,这种增加的压力会使更多的尘埃保留在大气中,大气中的水分将以雪或冰的形式落在尘埃颗粒上,计算表明这种物质将集中在中纬度地区[19][20],火星大气环流模式预测,富冰尘埃将会堆积在已发现有富冰特征的同一区域[21]。   当火星倾斜角逐惭回归到较低值时,水冰将会升华(直接变成气体)[22][22][23]并留下一层尘埃,留下的沉积覆盖了底层物质。所以每次自转轴的大幅度摇摆循环,都会使一些富冰层留在下面[24]。注意,光滑的表面覆盖层可能只代表相对较新的物质。

另请参阅

参考资料

  1. ^ The Color Palette of Nilosyrtis Mensae页面存档备份,存于互联网档案馆) at University of Arizona/HiRISE
  2. ^ "尼罗瑟提斯桌山群". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.  
  3. ^ Greeley, R. and J. Guest.  1987.  Geological map of the eastern equatorial region of Mars, scale 1:15,000,000. U. S. Geol. Ser. Misc. Invest. Map I-802-B, Reston, Virginia
  4. ^ Sharp, R.  1973.  Mars Fretted and chaotic terrains.  J. Geophys. Res.:  78.  4073-4083
  5. ^ Plaut, J. et al.  2008. Radar Evidence for Ice in Lobate Debris Aprons in the Mid-Northern Latitudes of Mars. Lunar and Planetary Science XXXIX. 2290.pdf
  6. ^ Carr, M. 2006. The Surface of Mars. Cambridge University Press. ISBN 978-0-521-87201-0
  7. ^ Squyres, S. 1978. Martian fretted terrain: Flow of erosional debrid. Icarus: 34. 600-613.
  8. ^ ISBN 0-8165-1257-4
  9. ^ Morgan, G. and J. Head III.  2009.  Sinton crater, Mars: Evidence for impact into a plateau icefield and melting to produce valley networks at the Hesperian-Amazonian boundary.  Icarus: 202. 39–59.
  10. ^ Morgan, G. et al.  2009.  Lineated valley fill (LVF) and lobate debris aprons (LDA) in the Deuteronilus Mensae northern dichotomy boundary region, Mars: Constraints on the extent, age, and episodicity of Amazonian glacial events.  Icarus: 202. 22–38.
  11. ^ 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
  12. ^ Head, J., et al.  2006. Modification if the dichotomy boundary on Mars by Amazonian mid-latitude regional glaciation.  Geophys. Res Lett.  33
  13. ^ Plaut, J. et al.  2008. Radar Evidence for Ice in Lobate Debris Aprons in the Mid-Northern Latitudes of Mars. Lunar and Planetary Science XXXIX.  2290.pdf
  14. ^ 存档副本. [2020-11-02]. (原始内容存档于2021-03-09). 
  15. ^ Plaut, J., A. Safaeinili,, J. Holt, R. Phillips, J. Head, J., R. Seu, N. Putzig, A. Frigeri.   2009.  Radar evidence for ice in lobate debris aprons in the midnorthern latitudes of Mars.  Geophys. Res. Lett. 36. doi:10.1029/2008GL036379.
  16. ^ Touma J. and J. Wisdom.  1993.  The Chaotic Obliquity of Mars.  Science 259, 1294-1297.
  17. ^ Laskar, J., A. Correia, M. Gastineau, F. Joutel, B. Levrard, and P. Robutel.   2004.   Long term evolution and chaotic diffusion of the insolation quantities of Mars.  Icarus 170, 343-364.
  18. ^ Levy, J., J. Head, D. Marchant, D. Kowalewski.  2008.  Identification of sublimation-type thermal contraction crack polygons at the proposed NASA Phoenix landing site: Implications for substrate properties and climate-driven morphological evolution. Geophys. Res. Lett. 35. doi:10.1029/2007GL032813.
  19. ^ Levy, J., J. Head, D. Marchant.   2009a. Thermal contraction crack polygons on Mars: Classification, distribution, and climate implications from HiRISE observations.  J. Geophys. Res. 114. doi:10.1029/2008JE003273.
  20. ^ Hauber, E., D. Reiss, M. Ulrich, F. Preusker, F. Trauthan, M. Zanetti, H. Hiesinger, R. Jaumann, L. Johansson, A. Johnsson, S. Van Gaselt, M. Olvmo.  2011.  Landscape evolution in Martian mid-latitude regions:  insights from analogous periglacial landforms in Svalbard.  In: Balme, M., A. Bargery, C. Gallagher, S. Guta (eds).   Martian Geomorphology.  Geological Society, London.  Special Publications: 356.  111-131
  21. ^ Laskar, J., A. Correia, M. Gastineau, F. Joutel, B. Levrard, and P. Robutel.   2004.   Long term evolution and chaotic diffusion of the insolation quantities of Mars.  Icarus 170,  343-364.
  22. ^ 22.0 22.1 Mellon, M., B.  Jakosky. 1995. The distribution and behavior of Martian ground ice during past and present epochs.  J. Geophys. Res. 100, 11781–11799.
  23. ^ Schorghofer, N., 2007. Dynamics of ice ages on Mars. Nature 449, 192–194.
  24. ^ Madeleine, J., F. Forget, J. Head, B. Levrard, F. Montmessin.   2007.  Exploring the northern mid-latitude glaciation with a general circulation model.  In:  Seventh International Conference on Mars.  Abstract 3096.