The U-Pb ages of fine-grained zircon separated from 2 dust-dominated soils in
the eastern highlands of south-eastern Australia and measured by ion
microprobe (SHRIMP) revealed a characteristic age ‘fingerprint’
from which the source of the dust has been determined and by which it will be
possible to assess the contribution of dust to other soil profiles. The 2
soils are dominated by zircon 400–600 and 1000–1200 Ma old,
derived from Palaeozoic granites and sediments of the Lachlan Fold Belt, but
also contain significant components 100–300 Ma old, characteristic of
igneous rocks in the New England Fold Belt in northern New South Wales and
Queensland. This pattern closely matches that of sediments of the
Murray-Darling Basin, especially the Mallee dunefield, suggesting that
weathering of rocks in the eastern highlands has contributed large quantities
of sediment to the arid and semi-arid inland basins via internally draining
rivers of the present and past Murray–Darling River systems, where it
has formed a major source of dust subsequently blown eastwards and deposited
in the highland soils of eastern Australia.
Magmatic and hydrothermal zircon growth during multiple orogenic cycles in an evolving mantle wedge
