Abstract
AbstractLinear dunes occur on planetary surfaces, including Earth, Mars, and Titan, yet their dynamics are poorly understood. Recent studies of terrestrial linear dunes suggest they migrate by elongation only in supply‐limited environments. Here, we investigate elongating linear dunes in the Hellespontus Montes region of Mars which are morphologically similar to terrestrial systems. Multitemporal, high‐resolution orbital images show these linear dunes migrate by elongation only and that the fixed sediment source of the dunes probably restricts any lateral migration. Some linear dunes maintain their along‐length volume and elongate at rates comparable to adjacent barchans, whereas those which decrease in volume show no elongation, suggesting they are near steady state, matching morphometric predictions. Limited sediment supply may restrict Martian linear dunes to several kilometers, significantly shorter than many terrestrial linear dunes. Our results demonstrate the close similarities in dune dynamics across the two planetary surfaces.
Highlights
Aeolian bedforms on planetary surfaces are a record for wind regime, past and current climate, erosion rates, and availability of sediment (e.g., Banham et al, 2018; Bridges et al, 2012; Chojnacki et al, 2019; Day & Catling, 2019; Fenton, 2006)
Some linear dunes maintain their along‐length volume and elongate at rates comparable to adjacent barchans, whereas those which decrease in volume show no elongation, suggesting they are near steady state, matching morphometric predictions
No multitemporal High Resolution Imaging Science Experiment (HiRISE) images were available for Meroe Patera, nearby barchan activity suggests the linear dunes are likely active and their morphology is consistent with ongoing elongation
Summary
Aeolian bedforms on planetary surfaces are a record for wind regime, past and current climate, erosion rates, and availability of sediment (e.g., Banham et al, 2018; Bridges et al, 2012; Chojnacki et al, 2019; Day & Catling, 2019; Fenton, 2006). Recent laboratory and numerical experiments demonstrate that in sediment‐starved regions (e.g., with nonerodible bedrock), linear dunes develop by elongation at the dune tips, aligned with the mean sediment transport direction (“finger‐mode”; Courrech du Pont et al, 2014; Gao et al, 2015; Reffet et al, 2010). This growth mechanism is supported by recent investigations of the Ténéré desert, Niger, where linear dunes develop on the lee of mesas, in an otherwise sand‐starved region, and migrate by elongation only, with no lateral migration component (Figure 1a; Lucas et al, 2015). The aim of our study is to understand whether the predicted and observed dynamics of terrestrial elongating linear dunes applies to Martian systems
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