Lateral migration of linear dunes in the Strzelecki desert, Australia

Abstract

AbstractLinear dunes in the Strzelecki Desert trend roughly south‐north. Sand transport, which is toward the NNE, has caused the dunes to migrate eastward while they extend or migrate northward. Eastward lateral migration is evidenced by: (1) asymmetrical shape of the dunes; east‐facing slopes are several times as steep as west‐facing slopes; (2) asymmetrical accumulation of loose recently transported sand (relatively abundant on east‐facing slopes); (3) asymmetrical outcropping of older semiconsolidated aeolian sand on the dune surface (more abundant on west‐facing slopes); and (4) east‐dipping foreset beds that underly the west‐facing flanks of some dunes. Dunes in the Strzelecki Desert are still active in the sense that sand is transported along and across many dune crests. However, the dunes are composed primarily of Pleistocene strata, indicating that the trend of the dunes was established before the Holocene.The obliquity of the dunes to the transport direction is not merely an aberration of the wind regime of the last few decades. Preferential accumulation of sand on east‐facing flanks indicates that the dunes migrated eastward several metres during the Holocene. Moreover, the west‐facing flanks of some dunes have experienced a minimum of tens of metres of erosion. This asymmetric erosion and deposition were caused by dune obliquity and lateral migration that may have begun as early as the Pleistocene.Dunes in the Strzelecki Desert and in the adjacent Simpson Desert display a variety of grossly different internal structures. Computer graphics experiments demonstrate that many of these differences in structure can be explained by different angles of climb of the dunes.