Late Amazonian glaciation at the dichotomy boundary on Mars: Evidence for glacial thickness maxima and multiple glacial phases
Late Amazonian glaciation at the dichotomy boundary on Mars: Evidence for glacial thickness maxima and multiple glacial phases
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火星二分边界处的亚马逊晚期冰川作用：冰川厚度最大值和多个冰川阶段的证据
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发表时间：
2008
期刊：
影响因子：
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通讯作者：
D. Marchant
中科院分区：
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作者：
J. Dickson;J. Head;D. Marchant
线状山谷填充（LVF）在侵蚀山谷的二分法边界已被解释为冰川的起源。未知的是（1）冰川冰的原始厚度，（2）通过升华和退缩，冰面下降到目前观察到的水平的数量，以及（3）是否有多个冰川期。我们解决这些问题，通过分析LVF冰川系统。在研究现场，先前高位的上限与LVF当前表面之间的高差约为920 m。我们将这种差异解释为冰川系统冰面下降的最小量。与一般降低的冰面一致的是多个冰碛和/或trimmlines，以及LVF流动模式的变化，因为冰退缩和厚度减少。几个裂片的叠加到当前的表面LVF表明，高山冰川作用的一个阶段，随后降低的山谷冰川系统。这些数据表明，在该地区产生LVF的晚亚马逊冰川作用涉及的冰量比以前认为的要大得多，随后的高山冰川作用也随之而来。
Lineated valley fill (LVF) in fretted valleys at the dichotomy boundary has been interpreted as glacial in origin. Unknown are (1) the original thickness of the glacier ice, (2) the amount of ice-surface lowering, through sublimation and retreat, to its presently observed level, and (3) whether there were multiple periods of glaciation. We address these questions through analysis of an LVF glacial system. The elevation difference between the upper limit of a previous highstand and the current surface of the LVF at the study site is ~920 m. We interpret this difference to be the minimum amount of ice-surface lowering of the glacier system. Consistent with a general lowering of the ice surface are multiple moraines and/or trimlines, and changes in LVF flow patterns, as the ice retreated and decreased in thickness. The superposition of several lobes onto the current surface of the LVF indicates that a phase of alpine glaciation followed the lowering of the valley glacial system. These data suggest that the Late Amazonian glaciation that produced LVF in this region involved significantly larger amounts of ice than previously thought, and that subsequent alpine glaciation followed.