Australia: The Land Where Time Began |
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Strzelecki Desert
& Tirari Desert – Timing of Linear Dune Activity There are linear dunes covering more than 1/3
of the Australian continent, but it is only poorly understood when they
formed. In this study Fitzsimmons et
al. collected 82 samples from
26 sites across the Strzelecki and Tirari Deserts, located in the driest
part of central Australia, to provide an optically stimulated
luminescence chronology (OSL) of these dunefields. There are up to 4
stratigraphic horizons preserved in these dunes, bounded by palaeosols,
which provide evidence of multiple reactivation periods that are
punctuated by episodes during which there was increased environmental
stability. Dune activity occurred in episodes about 73-65, 35-32, 22-18
and 14-10 ka. At other times intermittent partial mobilisation persisted
throughout the last 75 ka and it appears dune activity intensified
during the Late Holocene. At times when the sediment was available for
transport dune construction took place; this coincided with conditions
that were cold and arid in the Strzelecki and Tirari Deserts during
Marine Isotope Stage (MIS) 4, late MIS 3 and MIS 2, and the warm dry
climates of the late Pleistocene-Holocene period of transition and the
Late Holocene. During the humid periods of MIS 5 localised influxes of
sediment on active flood plains and the floors of lakes resulted in the
formation of dunes. Widespread reactivate of dunes coincided with times
of glaciation in southeastern Australia, along with cooler temperatures
in the adjacent oceans and Antarctica.
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Author: M.H.Monroe Email: admin@austhrutime.com Sources & Further reading |