Formation of Linear Dunes and Other Secrets of the Simpson Desert, Australia

Details Formation of Linear Dunes and Other Secrets of the Simpson Desert, Australia Formation of Linear Dunes and Other Secrets of the Simpson Desert, Australia

Dec 2006

adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2006agufm.p31b0127c&link_type=abstract

American Geophysical Union, Fall Meeting 2006, abstract #P31B-0127

Other

1862 Sediment Transport (4558), 5415 Erosion And Weathering, 5464 Remote Sensing, 6225 Mars, 6281 Titan

Scientific paper

It is estimated that linear dunes represent 40 percent of all dunes on Earth. Linear dunes have also been found on every terrestrial planet with an appreciable atmosphere, including Mars, Venus and Titan. Remarkably, however, despite how prevalent they are very little is known about their formation, chronology and their interaction with adjacent sediment sources. There are two basic hypotheses regarding the origin of linear dunes. The "wind rift" concept suggests that linear dunes are swept together from local material. In this model wind moves across the surface as horizontal vortices scouring or channeling out alluvial sand deposits [Pell et al., 1999; 2000]. The linear nature of the dunes is attributed to the parallel direction of the vortices. In the "depositional" concept sand is thought to come from a few depositional sources which can then be transported great distances. In this model linear dunes are a result of bidirectional winds that blow the sand together from either direction [Wopfner and Twidale, 2001]. Recently we began a series of studies in the Simpson Desert of Australia to tests these competing hypotheses. The Simpson Desert is located in the Lake Eyre basin and borders the Northwest Territory, Queensland and South Australia. Typically the area receives less than 150 mm (6 inches) of rain annually, and the rivers that drain into the Simpson Desert terminate in a series of floodout deposits where the flood waters simply debouch into the desert and seep into the sand leaving behind fresh sediment deposits. There is evidence indicating that these alluvial sediments are subsequently reworked into new dunes [Hollands et al., 2006]; however, the mechanism and timing of these processes is poorly understood. Using Differential Global Positioning System (DGPS) equipment we conducted a series of topographic surveys of linear dunes located in the western and southern parts of the Simpson Desert. Several of these dunes were staked so that we can monitor changes in dune morphometry over time. Results of the DGPS survey were also compared to Shuttle Radar Topographic Mission (SRTM) data as a way of verifying the accuracy of these data so that dune morphometry can be studied in a more systematic way. Our results will help us to better understand how linear dunes form and the environmental conditions necessary to generate them on Earth and on other terrestrial planets.

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