Sedimentology and geomorphology of Lake Yamma Yamma - A long-lived structurally controlled playa lake of the Lake Eyre Basin, Australia

ABSTRACT Intraplate tectonism and continental climate change have important roles in the evolution of the arid Lake Eyre Basin, one of the world’s largest interior basins, and a place with economic, environmental, and cultural significance for many Australians. Just off one of the main rivers of the Basin, Cooper Creek, Lake Yamma Yamma – a 20 km by 40 km ephemeral feature – traps sediment ~750 km upstream and ~90 m higher than the ultimate base level of the Basin – Kati Thanda-Lake Eyre. This paper is the first to report on the sedimentology and geomorphic evolution of this modern ephemeral playa lake. Field-based sedimentology, laboratory-based grain size analysis, satellite image interpretation, inundation frequency maps, hydrological data, and digital elevation data, were used to interpret sedimentary processes and the evolution of the lake. Results suggest Lake Yamma Yamma is a long-lived feature. Evolution is primarily structurally controlled, with the main lake delta migrating north-west over time. Quaternary fluvial, lacustrine and aeolian deposition is likely controlled by intraplate tectonism, and palaeo-shorelines may be remnant features of a prior climate regime. Age dating of this sedimentary archive could provide important information on the history, palaeoclimate, and evolution of the Lake Eyre Basin, and the Australian continent.