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Abstract:
Desert margins preserve evidence of more extensive arid conditions in the past and represent global hot spots with respect to climate change. The balance of scientific evidence now suggests that dryland landscape reactivation did not correspond simply to ice age aridity peaks as previously assumed. This paper provides a new perspective on, and more nuanced understanding of, desert marginal landscapes as palaeoenvironmental archives.
The two case studies represent ends of a sediment availability spectrum. Both environments experience substantial spatial and temporal variability in deposition, with implications for reconstructing past environments at individual sites. Recently generated chronostratigraphic data from the dry subhumid Dobrogea loess, Romania, are synthesised to provide quantitative insights into the spatial and temporal organisation of loess plateaux. Loess accumulation peaks during the LGM and MIS4, but not at all sites. Accumulation rates vary substantially between sites. Comparison of geographical context yields no clear driving mechanism for this variability. Secondly, two transverse lunette dunes in semi-arid Willandra Lakes, Australia, yield comparable chronostratigraphies and distribution of stratigraphic units. A first attempt is made to identify changes in wind regime through time on the Australian desert margins, and suggests that high latitude climate forcing may have acted upon semi-arid Australia over millennial scales.
The novel perspectives generated from the new datasets provide unprecedented insights into past climate circulation and land surface processes along desert margins. These new perspectives, coupled with the new geochronological and quantitative palaeoclimate proxy tools now available, represent the next frontier for palaeoenvironmental research on desert margins.
