GPR surveys of vegetated linear dune stratigraphy in central Australia: Evidence for linear dune extension with vertical and lateral accretion

Abstract

Linear dunes are the most abundant type of desert dune and the dominant land-form on the continent of Australia. This paper reports the results of GPR surveys across linear dunes in the deserts of central Australia including parts of the Simpson and Strzelecki deserts. The GPR data suffered from severely limited penetration and poor resolution due to signal attenuation associated with a high proportion of mud, which, probably due to progressive illuviation, increases with dune age. However, although such conditions prevail in much of central Australia, useful stratigraphic information can still be obtained there using GPR. Buried palaeosol horizons within dunes have been identified, and taken in conjunction with thermoluminescence (TL) ages from the dunes, it is possible to make some interpretations of linear dune evolution. TL ages show that some dunes are older in the south and young toward the north. It is possible to place some constraints on rates of vertical, lateral, and dune-front accretion within the linear dunes with ∼ 2-6 m, 0-50 m and 3000 m, respectively, over the last ca. 10 ka. The combination of GPR profiles and TL dating of linear dunes in the Simpson and Strzelecki deserts confirms Holocene modification of preexisting linear dunes with minor easterly accretion that has contributed to the asymmetry of vegetated linear dunes in central Australia. The results support the hypothesis that linear dunes in Australia are composite forms with a long and sometimes complex history. © 2007 The Geological Society of America. All rights reserved.