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- Title
Orbital and In Situ Investigation of the Bagnold Dunes and Sands of Forvie, Gale Crater, Mars.
- Authors
Moreland, E. L.; Arvidson, R. E.; Morris, R. V.; Condus, T.; Hughes, M. N.; Weitz, C. M.; VanBommel, S. J.
- Abstract
The Bagnold linear dune field investigated by Curiosity at Mount Desert Island (MDI) is north of the ∼5.5 km high Aeolis Mons mound in Gale crater. False‐color images (RGB: 2.496, 1.802, and 1.237 μm, respectively) generated from Mars Reconnaissance Orbiter Compact Reconnaissance Imaging Spectrometer for Mars (CRISM) data show the dune field has a reddish‐brown color. The Sands of Forvie (SoF), located ∼2.5 km to the southeast of MDI, is darker and lacks the reddish‐brown color. Single scattering albedo (SSA) spectra retrieved at 12 m/pixel using along‐track oversampled CRISM observation FRT00021C92 show a long wavelength (1.7–2.5 μm) increase in albedo for MDI dunes. For the same wavelength interval, SoF is characterized by a broad ∼2.2 μm absorption feature, consistent with color differences between the two deposits. Checkerboard un‐mixing of the SSA image cube was used to isolate spectral endmembers within the MDI and SoF deposits. Radiative modeling of these CRISM spectral endmembers using Hapke (2012, https://doi.org/10.1017/CBO9781139025683) theory implies finer grain sizes, more pigeonite, plagioclase, and olivine, and less basaltic glass and augite for MDI as compared to the SoF deposit. These results are consistent with Curiosity‐based observations that MDI contains smaller ripples with overall finer grains, whereas SoF has large ripples with coarser grains on the crests. Although these sand deposits are only located ∼2.5 km away from one another, wind and local topographic controls are interpreted to have modulated grain sizes and mineralogy. Plain Language Summary: "The present is the key to the past" is a fundamental tenet of geological sciences. Studying modern‐day, active processes and products provides important insights into interpreting the ancient rock record. Previous studies using orbital imaging data and rover‐based observations show that wind‐blown sand deposits occur in many locations and cover a variety of ages in Martian rock records. Thus, study of modern Martian sand deposits is an important element for understanding the processes that produced ancient deposits in addition to providing information about the modern depositional environments. To that end we have pursued advanced processing of hyperspectral imaging data covering two separate, modern sand deposits that were visited and characterized by the Curiosity rover. We show that the Mount Desert Island (MDI) linear dunes, located in the large Bagnold dune field, have different mineral abundances and smaller grain sizes than the Sands of Forvie (SoF) sand sheet. These differences result, at least in part, from the competing processes of unconstrained dune migration (MDI) and topographically inhibited sand migration (SoF). This is the case even though the two deposits are the same age and only ∼2.5 km away from one another, thereby providing an important lesson for interpreting the ancient rock record. Key Points: Data show that modern sand in Bagnold dunes and Sands of Forvie (SoF), only ∼2.5 km apart, have different mineral abundances and grain sizesBagnold sand has finer grains with more pigeonite, plagioclase, olivine, and less basaltic glass and augite versus SoF sandThese differences result from unconstrained Bagnold sand migration as opposed to topographically inhibited migration in the SoF
- Subjects
MOUNT Desert Island (Me.); GALE Crater (Mars); SAND dunes; MARS rovers; GEOLOGICAL time scales; MARS (Planet); SOUND recordings
- Publication
Journal of Geophysical Research. Planets, 2022, Vol 127, Issue 11, p1
- ISSN
2169-9097
- Publication type
Article
- DOI
10.1029/2022JE007436