Geological Society London Special Publications · 2010 · 121 citations · 88 references
Natural SciencesEarth SciencesPaleobiologyPaleoclimatologySedimentologyDesertificationLandscape ChronologyChronology Of Vegetation ChangeDesert PlayasDesertification HistoryDryingLacustrine SedimentsLate Quaternary EnvironmentsPaleoenvironmental ChronologyRadiogenic Isotope Dating
Australian climate and vegetation have fluctuated dramatically through the Cenozoic, with warm reversals superimposed on a long‑term trend of drying and cooling that produced stony deserts, dunefields and playa lakes whose ages were previously uncertain. Recent luminescence dating of Late Quaternary lake, dune, and dust‑mantle records, together with palaeomagnetic reversal chronologies, have established the timing of these arid‑landscape fluctuations and the mid‑Pleistocene onset of playa conditions in closed basins. Cosmogenic isotope dating now places the formation of major arid landforms—such as the Simpson Desert dunefield and the Lake Eyre Basin stony deserts—in the early Pleistocene and late Pliocene, respectively, indicating a stepwise climatic drying that likely drove biological adaptation, though the precise timing of speciation relative to desert development remains to be clarified.
Abstract Australian climate and vegetation, known from marine and lacustrine sediments and fossils, varied dramatically throughout the Cenozoic Era, with several warm reversals superimposed on overall drying and cooling. A suite of landforms, including stony deserts, dunefields and playa lakes, formed in response to the advancing aridity but their age generally remained uncertain until fairly recently, owing to a lack of suitable dating methods. Within the last 5 years, the chronology of Late Quaternary fluctuations of lakes, dunes and dust-mantles has been established by luminescence dating methods, and mid-Pleistocene onset of playa conditions in a few closed basins has been estimated using palaeomagnetic reversal chronology. Only recently has it been shown, by cosmogenic isotope dating, that major tracts of arid landforms including the Simpson Desert dunefield, and stony deserts of the Lake Eyre Basin, were formed in early Pleistocene and late Pliocene times, respectively. These landscapes represent a stepwise response to progressive climatic drying and, speculatively, were accompanied by biological adaptations. Recent molecular DNA studies indicate that Australia's arid-adapted species evolved from mesic-adapted ancestors during the Pliocene or earlier, but whether speciation rapidly accompanied the development of stony deserts and other arid geomorphological provinces awaits further studies of arid landscape chronology.
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