Evidence for remnants of ancient ice‐rich deposits: Mangala Valles outflow channel, Mars
Evidence for remnants of ancient ice‐rich deposits: Mangala Valles outflow channel, Mars
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古代富含冰的沉积物遗迹的证据：火星曼加拉山谷流出通道
DOI：
10.1111/j.1365-3121.2005.00642.x
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发表时间：
2005
期刊：
影响因子：
2.4
通讯作者：
J. Head
中科院分区：
文献类型：
--
作者：
J. Levy;J. Head
高分辨率的航天器数据显示，在火星上古老的外流通道MangalaValles的地板上游存在一个独特的单元。与Mangala和其他流出通道的底部和边缘典型的冲刷、强烈侵蚀和流体动力学塑造的大量证据相反，该单元表面光滑，具有尖形边缘，叠加在冲刷的谷底上，并有广泛的凹坑。我们解释这个单位是升华滞后存款来自冰热边界层上的水洪水，形成了流出通道系统，和残留的洪水被困在通道低。这一解释进一步支持了当时的气候条件与今天的超干旱寒冷沙漠条件相似的可能性。来自古代火星地表下的冰冻洪水仍然可以保存在这些沉积物中，代表着有吸引力和可访问的外星生物勘探目标。
High‐resolution spacecraft data reveal the presence of a distinctive unit on the upper reaches of the floor of Mangala Valles, an ancient outflow channel on Mars. In contrast to abundant evidence for scour, intense erosion, and hydrodynamic shaping typical of the floors and margins of Mangala and other outflow channels, this unit is smooth‐surfaced, has cuspate margins, is superposed on the scoured valley floor, and is extensively pitted. We interpret this unit to be the sublimation lag deposit derived from an ice thermal boundary layer on the aqueous flood that formed the outflow channel system, and the remnant of floodwaters trapped in channel lows. This interpretation further supports the likelihood that climate conditions at the time of emplacement were similar to the hyper‐arid cold desert conditions of today. Frozen floodwaters from the ancient martian subsurface could still be preserved in these deposits, representing attractive and accessible exobiological exploration objectives.