Sinuous ridges in Chukhung crater, Tempe Terra, Mars: Implications for fluvial, glacial, and glaciofluvial activity
Sinuous ridges in Chukhung crater, Tempe Terra, Mars: Implications for fluvial, glacial, and glaciofluvial activity
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火星坦佩泰拉 Chukhung 陨石坑的蜿蜒山脊：对河流、冰川和冰川河流活动的影响
DOI：
10.1016/j.icarus.2020.114131
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发表时间：
2021
期刊：
影响因子：
3.2
通讯作者：
Butcher F
中科院分区：
文献类型：
--
作者：
Butcher F
本文给出了火星滕佩Terra中部的Chukhung陨石坑（38.47°N，72.42°W）的地貌图。Chukhung陨石坑形成于大约3.6-2.1 Ga，在火星地质历史的早期西方和早期亚马逊时期之间。它拥有火山口壁谷的树枝状网络，宽阔的火山口底谷，中晚期亚马逊时代的碎片覆盖的冰川，冰碛状沉积物，以及弯曲的山脊地貌的放射状组合。我们探索Chukhung火山口地貌的起源，特别是在蜿蜒的山脊上。在北方楚科奇陨石坑，蜿蜒的山脊从北方陨石坑壁上的河谷系统向下延伸。我们将北方蜿蜒的山脊解释为倒置的古河道：由抗蚀和/或硬化的河道充填沉积物的折返形成的山脊。Chukhung火山口南部底部蜿蜒山脊的起源更加模糊。它们从冰碛状的山脊下出现，这些山脊束缚着从火山口南壁延伸出来的覆盖着冰川的现存碎片。南部蜿蜒的山脊有许多形态和环境的相似之处eskers：冰川河流沉积物沉积在融水管道内或湿基冰川下的山脊。然而，由于北方和南方弯曲山脊非常接近，因此对每一组山脊的不同起源的解释产生了疑问。esker和反向河道形成之间总体过程的相似性（即，通过移除边界介质（冰或沉积物/岩石）而暴露，导致了埃斯克斯和倒置古河道之间的形态会聚。我们详细讨论了南部蜿蜒的山脊的埃斯克特征，并认为在楚科奇陨石坑南部的两个山脊人口之一是最好的解释埃斯克假说，而另一个可以解释下的埃斯克或倒置的古河道假说。不管南部蜿蜒山脊的具体形成机制如何，我们发现Chukhung陨石坑自形成以来一直受到液态水的显著影响。北方蜿蜒的山脊和相关的火山口壁山谷提供了降水和/或融雪的陆上排水的证据。这表明Chukhung陨石坑，可能还有周围地区，在早期西方和亚马逊河流域中期之间经历了异常温暖和潮湿的时期。如果部分或全部南部蜿蜒的山脊是埃斯克斯，他们可以提供证据，在亚马逊河中晚期的冰川融水在Chukhung陨石坑的额外影响。如果Chukhung陨石坑确实发生了湿基冰川作用，那么该陨石坑位于滕佩槽沟构造裂谷系统的主要分支之间，这将增加越来越多的证据，证明地热热通量升高是火星最近局部发生湿基冰川作用的重要驱动因素。
We present a geomorphic map of Chukhung crater (38.47°N, 72.42°W) in central Tempe Terra, Mars. Chukhung crater formed ~3.6–2.1 Ga, between the early Hesperian and early Amazonian periods of Mars' geologic history. It hosts dendritic networks of crater wall valleys, broad crater floor valleys, mid- to late-Amazonian-aged debris-covered glaciers, moraine-like deposits, and a radial assemblage of sinuous ridge landforms. We explore the origins of landforms in Chukhung crater, focusing in particular upon the sinuous ridges. In northern Chukhung crater, sinuous ridges extend downslope from fluvial valley systems on the northern crater wall. We interpret the northern sinuous ridges as inverted paleochannels: ridges formed by exhumation of resistant and/or indurated fluvial channel fill deposits. The origins of sinuous ridges on the southern floor of Chukhung crater are more ambiguous. They emerge from beneath moraine-like ridges which bound extant debris-covered glaciers extending from the southern wall of the crater. The southern sinuous ridges have numerous morphological and contextual similarities to eskers: ridges of glaciofluvial sediment deposited in meltwater conduits within or beneath wet-based glaciers. The close proximity of the northern and southern sinuous ridges, however, calls into question an interpretation which ascribes a different origin to each set. The similarity in the overarching process between esker and inverted channel formation (i.e., exposure by the removal of a bounding medium, be that ice or sediments/rock) results in convergence of form between eskers and inverted paleochannels. We discuss the esker-like characteristics of the southern sinuous ridges in detail, and argue that one of two ridge populations in southern Chukhung crater is best explained by the esker hypothesis while the other could be explained under either the esker or the inverted paleochannel hypothesis. Regardless of the specific formation mechanism for the southern sinuous ridges, we find that Chukhung crater has undergone significant modification by liquid water since its formation. The northern sinuous ridges and associated crater-wall valleys provide evidence for subaerial drainage of precipitation and/or snowmelt. This suggests that Chukhung crater, and possibly the surrounding region, experienced unusually warm and wet episodes between the early Hesperian and mid Amazonian. If some or all of the southern sinuous ridges are eskers, they could provide evidence for an additional influence of glacial meltwater in Chukhung crater during the mid-to-late Amazonian. If wet-based glaciation did occur in Chukhung crater, the location of the crater between major branches of the Tempe Fossae tectonic rift system would add to the growing body of evidence that elevated geothermal heat flux was an important driver of localized occurrences of recent wet-based glaciation on Mars.
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