Some aligned claypans in the Strzelecki dunefield, Central Australia

Abstract

Sets of claypans in the Strzelecki dunefield are commonly aligned obliquely or almost perpendicular to the trend of longitudinal (seif) dunes. The claypan alignments form an arcuate convex‐north pattern in the dunefield. Three types of claypan define the alignments: i. Floodflats and/or lakes associated with curved portions of modern or palaeoriver systems. These were major sources of aeolian sediments.ii. Sets of small claypans developed downwind from lakebeds, including salt lakes, and from type 1 claypans. These claypans form in swales between transverse dunes. The swales are crossed by longitudinal dunes.iii. Claypans not associated with river systems or salt lakes. These formed by wind erosion of the pre‐existing land surface. The aligned claypans probably formed as a result of Pleistocene aeolian erosion and deposition, coincident with development of the dunefield. The arcuate pattern probably reflects variations in wind‐strength, greatest in the central area and lesser near rocky rises on the margin of the field. A previous explanation for the claypans is that they resulted from gradual diminution of a mega‐lake, Lake Dieri, during the Late Tertiary to Late Quaternary. There is evidence for extensive lacustrine facies during the Miocene‐Pliocene, but many of the aligned claypans are developed on younger fluvial deposits. Undoubtedly the major existing lakes in the region have fluctuated in size during the Quaternary, but no evidence relates the aligned claypans to the previously proposed mega‐lake.