142-7 Paleoclimate in Exposed Layers of Pedestal Craters On Mars

Session: Geomorphology and Landscape Evolution of Mars (Posters)

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Abstract:

Pedestal craters on Mars are impact craters surrounded by a plateau-like ejecta blanket which have tens of meters of topographic relief [1]. These features are thought to form when impact ejecta protects underlying material from subsequent erosion. Previous research has shown that these features are most likely icy due to characteristics like external layering, low dielectric constant [2], and sublimation pits along the margins [3]. Pedestal craters are significant because they could preserve evidence of past surface conditions and climate-driven processes, particularly in mid-latitude regions where ice-rich deposits are inferred to have been widespread during the Amazonian period [4, 2]. Here, we conduct preliminary analysis of HiRISE images of a pedestal crater in the southern hemisphere revealing 17 distinct, well-preserved layers exposed in the pedestal walls. These layers likely represent episodic deposition of icy material over different climates from Mars’ changing orbital conditions. We also performed preliminary SHARAD analysis near the external layers in the HiRISE images. We were able to identify multiple subsurface reflectors and there appears to be about 7 resolvable internal layers. Additionally, using SHARAD we found a dielectric constant of this pedestal to be approximately 5.3. This value would indicate that the pedestal is rich in water-ice and sediments. Our future work plans to examine more pedestal craters across Mars including performing HiRISE-scale topographic analysis to reveal what their external and internal layers reveal about the past climate.

[1] McCauley, J. F., (1973), J. Geophys. Res., 78(20), 4123–4137. [2] Nunes, D. C., et al., (2011), J. Geophys. Res., 116, E04006. [3] Kadish, S. J., et al., (2008), Geophys. Res. Lett., 35, L16104. [4] Arvidson, R. E., (1976), Icarus, vol. 27, 4, 503-516, ISSN 0019-1035.

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