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首页> 外文期刊>Planetary and space science >Morphological and mechanical characterization of gullies in a periglacial environment: The case of the Russell crater dune (Mars)
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Morphological and mechanical characterization of gullies in a periglacial environment: The case of the Russell crater dune (Mars)

机译：冰川环境中沟壑的形态和力学特征：以罗素火山口沙丘（火星）为例

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摘要

Gullies on terrestrial sand dunes are rare, and their presence on Mars, as well as their mechanical properties, and the quantity of fluid required for their formations currently remain poorly understood. This study focuses on gully morphologies on the Russell megadune (54.5 S; 12.7 E) using High Resolution Imaging Science Experiment (HiRISE) images and Digital Terrain Models (DTM). Based on the scenario of ground ice melting in a periglacial environment, we propose to test the hypothesis that Martian gullies on dunes are debris flows. This implies a flow with a significant proportion of liquid water ( > 10% in volume). We used an original method to study Martian gullies based on empirical equations from terrestrial debris flows in order to calculate the physical properties of Martians flows. We observe a decrease in viscosity induced by the relative increase of fluid concentration (from 28% to 39%) during the flow advance. The total estimated volume of eroded and deposited material range from ～14850 m~3 to ～18890 m~3. The volume of liquid water required to generate one gully ranges from 4450 m~3 to 6900 m~3. The calculated results for Martian gullies are consistent with terrestrial studies on debris flows. Based on a morphological description and on the estimated physical parameters, we propose a model for gully formation on Martian dunes. The melt water from near-surface ground ice is incorporated in the debris flow and water concentration increases during its propagation. The increase of water concentration in the debris flow can be explained by a progressive increase of water/ice content in the permafrost downstream. Consequently, the lack of a final deposit at the front of the gullies tends to demonstrate that the flow became relatively highly concentrated in liquid downstream and all the water could have been lost in the final stage of the flow. This process could explain the lack of terminal lobes at the front of the gullies. We conclude that a process of formation similar to terrestrial debris flows is plausible. The large amount of liquid water involved requires formation of Martian gullies on dunes during a warmer climatic episode.
机译：地面沙丘上的沟壑很罕见，它们在火星上的存在以及它们的机械性能以及形成它们所需的流体量目前仍知之甚少。这项研究使用高分辨率成像科学实验（HiRISE）图像和数字地形模型（DTM）来研究罗素巨型沙丘（54.5 S; 12.7 E）上的沟渠形态。基于在冰川环境中地面冰融化的情况，我们建议检验沙丘上火星沟是泥石流的假设。这意味着流中含有大量的液态水（体积> 10％）。我们使用原始方法，根据来自地面泥石流的经验方程式研究火星沟，以计算火星流的物理特性。我们观察到在流动推进过程中，由于流体浓度的相对增加（从28％到39％）而引起的粘度降低。侵蚀和沉积物的总估计体积为〜14850 m〜3至〜18890 m〜3。产生一个水沟所需的液态水量为4450 m〜3至6900 m〜3。火星沟壑的计算结果与泥石流的地面研究一致。基于形态描述和估计的物理参数，我们提出了火星沙丘上的沟壑形成模型。来自近地表冰的融化水合并到泥石流中，并且在其传播过程中水浓度增加。泥石流中水浓度的增加可以用下游多年冻土中水/冰含量的逐渐增加来解释。因此，在集水沟的前部没有最终的沉积物，这往往表明水流在下游的液体中变得相对集中，并且在水流的最后阶段可能已经失去了所有的水。这个过程可以解释沟渠前面没有末端裂片的原因。我们得出的结论是，类似于陆地泥石流的形成过程是合理的。所涉及的大量液态水需要在气候变暖期间在沙丘上形成火星沟。

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  • 来源
    《Planetary and space science》 |2012年第1期|p.38-54|共17页
  • 作者

    Gwenaeel Jouannic; Julien Gargani; Francois Costard; Gian G. Ori; Chiara Marmo; Frederic Schmidt; Antoine Lucas;

  • 作者单位

    IDES, Universite Paris-Sud, CNRS UMR 8148, Bat. 509, 91405 Orsay, France,International Research School of Planetary Sciences, Universita 'G. d'Annunzio', Viale Pindaro 42, 65127 Pescara, Italy;

    IDES, Universite Paris-Sud, CNRS UMR 8148, Bat. 509, 91405 Orsay, France;

    IDES, Universite Paris-Sud, CNRS UMR 8148, Bat. 509, 91405 Orsay, France;

    International Research School of Planetary Sciences, Universita 'G. d'Annunzio', Viale Pindaro 42, 65127 Pescara, Italy,Ibn Battuta Centre, Universste Cady Ayyad, Marrakech, Morocco;

    IDES, Universite Paris-Sud, CNRS UMR 8148, Bat. 509, 91405 Orsay, France;

    IDES, Universite Paris-Sud, CNRS UMR 8148, Bat. 509, 91405 Orsay, France;

    Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena, CA, USA;

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  • 原文格式 PDF
  • 正文语种 eng
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  • 关键词

    mars; water; gullies; digital topographic models; permafrost; sediment transport;

    机译：火星;水;沟渠;数字地形模型;多年冻土;泥沙输送;

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