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- Title
Re‐Evaluation of Large Martian Ripples in Gale Crater: Granulometric Evidence for an Impact Mechanism and Terrestrial Analogues.
- Authors
Gough, Tyler R.; Hugenholtz, Chris H.; Barchyn, Thomas E.
- Abstract
Mars hosts three scales of superimposed aeolian bedforms: small decimeter‐scale impact ripples, large meter‐scale ripples, and dunes. The formation mechanism for large meter‐scale ripples is enigmatic and debated. This debate is largely informed by two questions: (a) Are large ripples similar to any features on Earth? and (b) Do they have the same grain size distribution as dunes and impact ripples? We address these questions using a novel digitizing approach to produce the largest known data set of Mars ripple sand grain size to date. We find a distinction between the grain size distributions of small ripples and large ripples and suggest that analogous bedforms are found on Earth. Despite an inability to perform rigorous sedimentology on Mars, results help resolve outstanding questions in bedform physics and support a hypothesis that aeolian ripples on Mars develop by a terrestrially analogous impact mechanism. Plain Language Summary: Mars and Earth have many different sizes of sand ripples and sand dunes. The Curiosity rover took pictures of large sand ripples with one meter spacing between crests. On Earth these large ripples are often called "megaripples". However, it is hard to know if the meter‐scale ripples observed by Curiosity form in the same way as Earth's megaripples. To help solve this problem, we measured more than twenty thousand sand grains from close‐up images of the ripples taken by the Mars Hand Lens Imager on Curiosity. The method we used to measure the imaged grains simulates the measurement method used for real sand samples on Earth. Using a method like this is important because it allows for direct comparison between Earth sand and Mars sand. With this method, we find that the large ripples observed by Curiosity have larger sand grains than the smaller ripples. Earth's megaripples also have larger grains than smaller ripples. The difference in sand grain size we measured provides evidence that large Martian ripples form in a way that is similar to Earth's "megaripples". Key Points: A new data set of surface sediment texture is used to test the fluid drag and impact hypotheses of large wind‐formed Martian ripplesLarge wind ripples have coarser and more poorly sorted surface sediment than nearby smaller ripplesThe surface sediment of large wind ripples on Mars is consistent with an impact mechanism, not fluid drag
- Subjects
RIPPLES (Fluid dynamics); GALE Crater (Mars); ERGS (Landforms); SAND dunes; SEDIMENTS
- Publication
Journal of Geophysical Research. Planets, 2021, Vol 126, Issue 12, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2021JE007011