Thermophysical and Compositional Analyses of Dunes at Hargraves Crater, Mars

A Emran,D T King Jr,L J Marzen,V F Chevrier

doi:10.3847/psj/ac25ee

Abstract

Abstract We analyze thermal emission spectra using the 2001 Mars Odyssey Thermal Emission Imaging System and the Mars Global Surveyor Thermal Emission Spectrometer to characterize grain size and mineralogical composition of dunes at Hargraves crater, Mars. Thermal inertia and bulk composition of the dunes were compared to inferred provenances from the thermal infrared response of surface constituent materials. We use a Markov Chain Monte Carlo technique to estimate the bulk amount of mineralogy contributed by each inferred provenance to the dune field composition. An average thermal inertia value of 238 ± 17 Jm−2 K−1 s−0.5 was found for the dunes, corresponding to a surface composed of an average effective grain size of ∼391 ± 172 μm. This effective particle size suggests the presence of mostly medium sand-sized materials mixed with fine and coarse grain sands. The dunes are likely composed of a weakly indurated surface mixed with unconsolidated materials. Compositional analysis specifies that the dunes are composed of a mixture of feldspar, olivine, pyroxene, and relatively low bulk-silica content. Dune materials were likely derived from physical weathering, especially aeolian erosion, predominantly from the crater ejecta unit at the crater, mixed with a small amount from the crater floor and crater rim and wall lithologies—indicating that the dune materials were likely sourced locally.

Highlights

Despite a variety of environments involved, dune fields provide an important insight into eolian transport regimes of terrestrial planets (Greeley & Iversen 1987)
The result of the grain-size distribution for the dune materials was presented first followed by the results of dune morphology and stability, and bulk mineralogy of the dune field and the potential provenances
Thermal Emission Imaging System (THEMIS) nighttime data are more reliable than daytime data when deriving thermal inertia and estimating grain-size distribution because nighttime observation minimizes the effects of slope and albedo (Edwards et al 2018)

Summary

Introduction

Despite a variety of environments involved, dune fields provide an important insight into eolian transport regimes (both past and present) of terrestrial planets (Greeley & Iversen 1987). The surface of Mars is rife with eolian dune fields in a variety of locations e.g., the circum-north polar region (Edgett & Christensen 1991). Particle grain-size in dunes is actively influenced by nature of source materials, surface topography, transport medium, and the distance traveled from source to sink (Abuodha 2003). Eolian dunes of Mars are likely comprised of particle-sizes of homogenous materials within a dune field and, grain-size determination from thermal inertia is considered a reliable method (Edwards et al 2018)

Results

Discussion

Conclusion