Crenulated "Brain Terrain" in Arcadia Planitia, Mars
Abstract
The plains of Arcadia Planitia on Mars at 40°N and 200°E straddle the southern boundary of a latitude-dependent mantle (LDM) of shallow water-ice that holds key records for the planet's climate. Ice is not stable at mid-latitude surfaces today, but is expected to have precipitated in the past during different obliquities and climatic conditions with remnant excess ice preserved in the subsurface under a veneer of soil partially isolating it from the atmosphere. One indicator of ice in Arcadia is crenulated "brain coral" terrain comprised of alternating sinuous troughs and ridges, clearly resolved in 25 cm/pixel High Resolution Imaging Science Experiment (HiRISE) images. Similar morphologies have previously been identified in localized deposits within some craters at Utopia Planitia. However, this morphology is widespread in Arcadia - occurring over hundreds of kilometers and it transitions into pitted and more familiar polygonal terrain. It has been interpreted to form by differential sublimation of shallow subsurface ice, but the details of its formation and underlying structure are poorly understood leaving many basic questions unanswered. How much soil overburden is there, and how does soil thickness change from ridge to trough? Is the underlying ice pore-filling or massive? Why do the crenulations have a regular pattern with a consistent wavelength? What causes preferred orientations in some patches? No rocks are visible in the troughs, but are there any other foci that could cause differential sublimation over meter scales? Are there any direct analogs on Earth or icy satellites? And why is this morphology so widespread across the plains of Arcadia, but not elsewhere on Mars? Further analysis may shed light on this weird and wonderful morphology.
- Publication:
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AGU Fall Meeting Abstracts
- Pub Date:
- December 2017
- Bibcode:
- 2017AGUFM.P11A2497W
- Keywords:
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- 5464 Remote sensing;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 5499 General or miscellaneous;
- PLANETARY SCIENCES: SOLID SURFACE PLANETS;
- 8149 Planetary tectonics;
- TECTONOPHYSICS;
- 8450 Planetary volcanism;
- VOLCANOLOGY