Regular ArticleStar and Linear Dunes on Mars
Abstract
A field containing 11 star and incipient star dunes occurs on Mars at 8.8°S, 270.9°W. Examples of linear dunes are found in a crater at 59.4°S, 343°W. While rare, dune varieties that form in bi- and multidirectional wind regimes are not absent from the surface of Mars. The occurrence of both of these dune fields offers new insight into the nature of martian wind conditions and sand supply, The linear dunes appear to have formed through modification of a formerly transverse aeolian deposit, suggesting a relatively recent change in local wind direction. The 11 dunes in the star dune locality show a progressive change from barchan to star form as each successive dune has traveled up into a valley, into a more complex wind regime. The star dunes corroborate the model of N. Lancaster (1989, Progr. Physical Geogr. 13, 67-91; 1989, Sedimentology 36, 273-289) for the formation of star dunes by projection of transverse dunes into a complex, topographically influenced wind regime. The star dunes have dark streaks emanating from them, providing evidence that the dunes were active at or near the time the relevant image was obtained by the Viking 1 orbiter in 1978. The star and linear dunes described here are located in different regions on the martian surface. Unlike most star and linear dunes on Earth, both martian examples are isolated occurrences; neither is part of a major sand sea. Previously published Mars general circulation model results suggest that the region in which the linear done field occurs should be a bimodal wind regime, while the region in which the star dunes occur should be unimodal. The star dunes are probably the result of localized complication of the wind regime owing to topographic confinement of the dunes. Local topographic influence on wind regime is also evident in the linear dune field, as there are transverse dunes in close proximity to the linear dunes, and their occurrence is best explained by funneling of wind through a topographic gap in the upwind crater wall.
References (0)
Cited by (44)
The distribution and nature of star dunes: A global analysis
2021, Aeolian ResearchStar dunes, which occur on Mars and Titan and are also evident in Earth’s stratigraphic record, are widespread in the world’s drylands and 25 provinces have been identified and characterised based on an analysis of Google Earth images. They occur in East Asia, Western Asia, the Americas, southern Africa and northern Africa. Star dunes are absent in inland Australian, Kalahari and Indian sand seas and in the southern Sahara. Morphometric measurements across a wide range of sites reveal star dune densities of 7 to 81 per 100 km2 (mean 30 per km2), dune widths of 125–3071 m (mean 895 m) and heights of 4–291 m (mean 75 m). Star dunes have a great diversity of forms, which include simple pyramids, complex features, checkerboard patterns, symmetrical and asymmetrical forms, stars along linear dunes and stars along transverse dunes. In some areas star dunes show an association with mega-domes. In this paper they are classified into 10 types, though it is clear that some dunes may show characteristics of more than one type. Star dunes develop in areas with low rainfall, variable wind directions and in association with topographic barriers. They are a more widespread and varied phenomenon than has previously been recognised.
Star dune, the most complex type of single dune ever found, is known to be controlled by several natural factors including wind, topography, and sediment source. Anthropogenic impact of direct disturbance or modification on nearby land surface can also alter its shape and pattern over a longer timescale, but this factor is generally overlooked. Here, we present an integrated study of anthropogenic impact on a well-known star dune in the Mingsha Megadune of Dunhuang, China, by using 3D full-scale numerical simulations and wind tunnel experiments with printed 3D solid models. The removal of the tail of one dune arm affects both the leeward recirculation zone and the budge of dune surface; and an enlarged peripheral green land affects wind speed re-distribution and dune body displacement. The wind speed and direction variations were confirmed by field observations. We suggest that anthropogenic impact should be reduced to minimum or used to restore the setting to its previous state, for example, by removing the newly planted trees and rebuilding the dune arm tail, to maintain the natural balance between wind regime and aeolian landform, in order to protect this precious nature heritage from further deformation and degradation.
Dark dunes of mars: An orbit-to-ground multidisciplinary perspective of aeolian science
2018, Dynamic Mars: Recent and current landscape evolution of the red planetThe action of wind in the evolution of landscape for Mars is a dynamic mechanism that has longevity beyond many other recognized processes, and it is a mechanism that spans all geological and climatic eras. This chapter discusses the current understanding of dunefield geography, dune and ripple migration, variations in mineralogy between polar and equatorial dunefields, and the working of an extraterrestrial aeolian system, the Bagnold dunefield. Highlights from the in situ investigations by the Mars Science Laboratory's Curiosity will discuss the granulometry, geomorphology, mineralogy, geochemistry, activity, and history that the rover has discovered in the study of the Bagnold dunes, alongside the relationships the dunefield has with the regional geology, and to wind as a geological process.
Exploring morphology, layering and formation history of linear terrestrial dunes from radar observations: Implications for Titan
2018, Remote Sensing of EnvironmentUnderstanding the morphology and internal layering of large aeolian dune fields through radar observations can provide unique insights into the climatic and geophysical conditions that led to their formation. In this study, we perform a large-scale characterization of the morphology and internal layering of linear dunes in hyper-arid areas on Earth, through utilizing multiple complementary radar datasets (SIR-C imaging, SRTM interferometry-derived elevations and radar sounding or Ground Penetrating Radar (GPR)). Linear dune fields in the Egyptian desert are of special interest, due to their significance as planetary analogs to dunes on Mars and Saturn's largest moon, Titan. Satellite radar imagery and elevation data of the region show significant variance in the geomorphology of different dune fields in Egypt. In addition, GPR probing of the first few meters suggests different inner settings in the layering of dunes of different ages in eastern and western Egypt, reflecting different paleo-climatic regimes that led to their formation. Furthermore, our radiometric analysis suggests that dunes with different inner layering arrangement also exhibit different radar backscatter returns as a function of their heights. For relatively younger dunes with a homogeneous inner structure, like the ones in eastern Egypt in the Qattaniya dune field, we observe that sigma0 does not change as a function of the dune height. For relatively older dunes in western Egypt like the Great Sand Sea (Northern (Siwa) and Southern dune fields), we observed a linear correlation between sigma0 and the dune height. Thus, surface properties of dunes like morphology and backscatter variation with height are related to inner characteristics like arrangement of internal layering, relative ages and can be used to infer their depositional history.
Linear dunes discovered in the equatorial regions of Titan by the Cassini-Huygens mission are morphologically very similar to these linear dune fields in the Egyptian Sahara. Hence, assessing the variability of morphology and radar backscatter properties of Titan's dunes as a function of their heights can help constrain the ambiguities associated with their internal structure and formation history and provide insights into Titan's paleo-wind regimes.
Interpretations and common challenges of aeolian records from North American dune fields
2016, Quaternary InternationalGeomorphic and chronologic data for dune fields are evaluated for three contrasting areas of North America: 1) the Prairie, Parkland and Boreal ecozones of the northern Great Plains in Canada; 2) the Central Great Plains of the USA; and 3) the deserts of southwestern USA and northern Mexico. Luminescence and radiocarbon ages for periods of dune accumulation and stability are compared with palaeoenvironment proxies to provide an assessment of the boundary conditions of dune system response to changes in sediment supply, availability, and mobility.
Dune fields in the northern Great Plains were formed from sediment originating from glaciofluvial or glaciolacustrine sediments deposited during deglaciation 16–11 ka. Subsequent aeolian deposition occurred in Parkland and Prairie dune fields as a result of mid-Holocene (8–5 ka) and late-Holocene (<3.5 ka) activity related to drought conditions that reworked pre-existing aeolian sands. In the Central Great Plains, many dune fields are closely linked to fluvial sediment sources. Sediment supply was high during deglaciation of the Rocky Mountains and resulted in widespread dune construction 16–10 ka. Multiple periods of Holocene reactivation are recorded and reflect increased sediment availability during drought episodes. Dune fields in the southwestern deserts experienced periods of construction as a result of enhanced supply of sediment from fluvial and lacustrine sources during the period 11.8–8 ka and at intervals during the late Holocene centered on 1.5, 0.7, 0.4, 0.3, and 0.2 ka.
Despite spatial and temporal gaps in chronometric data as a result of sampling biases, the record from North American dune fields indicates the strong influence of sediment supply on dune construction, with changes in sediment availability as a result of drought episodes resulting in dune field reactivation and reworking of pre-existing sediment.
Quantifying geological processes on Mars - Results of the high resolution stereo camera (HRSC) on Mars express
2015, Planetary and Space ScienceThis review summarizes the use of High Resolution Stereo Camera (HRSC) data as an instrumental tool and its application in the analysis of geological processes and landforms on Mars during the last 10 years of operation. High-resolution digital elevations models on a local to regional scale are the unique strength of the HRSC instrument. The analysis of these data products enabled quantifying geological processes such as effusion rates of lava flows, tectonic deformation, discharge of water in channels, formation timescales of deltas, geometry of sedimentary deposits as well as estimating the age of geological units by crater size–frequency distribution measurements. Both the quantification of geological processes and the age determination allow constraining the evolution of Martian geologic activity in space and time. A second major contribution of HRSC is the discovery of episodicity in the intensity of geological processes on Mars. This has been revealed by comparative age dating of volcanic, fluvial, glacial, and lacustrine deposits.
Volcanic processes on Mars have been active over more than 4 Gyr, with peak phases in all three geologic epochs, generally ceasing towards the Amazonian. Fluvial and lacustrine activity phases spread a time span from Noachian until Amazonian times, but detailed studies show that they have been interrupted by multiple and long lasting phases of quiescence. Also glacial activity shows discrete phases of enhanced intensity that may correlate with periods of increased spin-axis obliquity. The episodicity of geological processes like volcanism, erosion, and glaciation on Mars reflects close correlation between surface processes and endogenic activity as well as orbit variations and changing climate condition.