Sinuous ridges in Chukhung crater, Tempe Terra, Mars: Implications for fluvial, glacial, and glaciofluvial activity

•We present a geomorphic map of Chukhung crater and interpret its geologic history.•Chukhung crater has been modified by fluvial, glacial, and aeolian processes.•Valleys & inverted paleochannels imply Hesperian and/or Amazonian fluvial activity.•Glacier-linked sinuous ridges may be eskers formed by Amazonian glacial meltwater.•Geothermal heating might explain esker-forming glacial melting in Chukhung crater. 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 wa