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Onset and migration of spiral troughs on Mars revealed by orbital radar

机译：轨道雷达显示火星上螺旋槽的发生和迁移

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摘要

The landscape of the north polar layered deposits of Mars (NPLD) is dominated by a pinwheel array of enigmatic spiral troughs. The troughs have intrigued planetary scientists since the Mariner 9 spacecraft returned the first close-up image in 1972, but conclusive evidence of their origin has remained elusive. Debate continues regarding all aspects of the troughs, including the possibility that they have migrated, their age in relation to the current NPLD surface, and whether they are fundamentally erosional or constructional features. The troughs are probably related to climatic processes, yet the nature of this relationship has remained a mystery. Previous data characterizing only the exposed NLPD surface were insufficient to test these hypotheses. Here we show that the central spiral troughs initiated after deposition of three-quarters of the NPLD, quickly reached a stable morphology and migrated approximately 65 kilometres poleward and 600 metres in altitude over the past two million years or so. Our radar stratigraphy rules out hypotheses of erosional incision post-dating deposition, and instead largely validates an early hypothesis for constructional trough migration with wind transport and atmospheric deposition as dominant processes. These results provide hard constraints for palaeo-climate models and a new context for evaluating imagery, spectral data, and now radar sounding data, the better to understand the link between orbital parameters and climate, the role of climate in shaping the polar ice of Mars, and eventually, the age of the polar deposits themselves.
机译：火星的北极分层沉积物（NPLD）的景观主要由神秘的螺旋槽风车阵列组成。自从水手9号飞船于1972年返回第一张特写照片以来，这些槽就吸引了行星科学家的兴趣，但是其起源的确凿证据仍然难以捉摸。关于水槽的各个方面的辩论仍在继续，包括水槽迁移的可能性，相对于当前NPLD表面的年龄以及从根本上讲是侵蚀性的还是建筑性的。低谷可能与气候过程有关，但是这种关系的性质仍然是个谜。仅表征暴露的NLPD表面的先前数据不足以检验这些假设。在这里，我们显示了中央螺旋槽在沉积了四分之三的NPLD之后开始，迅速达到了稳定的形态，并在过去两百万年左右的时间里向北极移动了约65公里，海拔迁移了600米。我们的雷达地层学排除了沉积后侵蚀性切口的假设，而很大程度上验证了以风速传输和大气沉积为主要过程的构造槽运移的早期假设。这些结果为古气候模型提供了严格的约束条件，并为评估图像，光谱数据以及现在的雷达探测数据提供了新的环境，从而更好地了解了轨道参数与气候之间的联系，气候在塑造火星极地冰块中的作用，并最终确定了极地的年龄。

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  • 来源
    《Nature》 |2010年第7297期|p.450-453|共4页
  • 作者

    Isaac B. Smith; John W. Holt;

  • 作者单位

    University of Texas Institute for Geophysics, Jackson School of Geosciences, Austin, Texas 78758, USA;

    University of Texas Institute for Geophysics, Jackson School of Geosciences, Austin, Texas 78758, USA;

  • 收录信息 美国《科学引文索引》(SCI);美国《工程索引》(EI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
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